From f72c428d2bcf314b83b672534b30a1bccdf82802 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 10:48:03 -0800
Subject: [PATCH 01/23] (debug)

---
 .github/workflows/main.yml | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 7bae4b335..f13bd3c35 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -215,20 +215,21 @@ jobs:
             # While UBSAN might work with LTO, I do not want the aggravation/entropy.  Turn it off.
             # Plus inheriting from regular RelWithDebInfo anyway.
             no-lto: true
+          # XXX trying -O1 for less craziness
           - id: relwithdebinfo-tsan
             conan-profile-build-type: RelWithDebInfo
             conan-profile-jemalloc-build-type: Release
             conan-profile-custom-conf: |
-              tools.build:cflags = ["-fsanitize=thread"]
-              tools.build:cxxflags = ["-fsanitize=thread"]
-              tools.build:sharedlinkflags = ["-fsanitize=thread"]
-              tools.build:exelinkflags = ["-fsanitize=thread"]
+              tools.build:cflags = ["-fsanitize=thread -O1"]
+              tools.build:cxxflags = ["-fsanitize=thread -O1"]
+              tools.build:sharedlinkflags = ["-fsanitize=thread -O1"]
+              tools.build:exelinkflags = ["-fsanitize=thread -O1"]
             conan-profile-custom-settings: |
               compiler.sanitizer = thread
             conan-profile-custom-buildenv: |
-              CXXFLAGS = -fsanitize=thread
-              CFLAGS = -fsanitize=thread
-              LDFLAGS = -fsanitize=thread
+              CXXFLAGS = -fsanitize=thread -O1
+              CFLAGS = -fsanitize=thread -O1
+              LDFLAGS = -fsanitize=thread -O1
             conan-custom-settings-defs: |
               data['compiler']['gcc']['sanitizer'] = ['None', 'address', 'thread', 'memory', 'undefined']
               data['compiler']['clang']['sanitizer'] = ['None', 'address', 'thread', 'memory', 'undefined']

From 7df7241ea10e6d25e1d2ace4992b6f63168d4026 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 13:04:01 -0800
Subject: [PATCH 02/23] Trying -O1 instead of -O2 with TSAN, as otherwise at
 least clang-17 transport_test/ex/SHM-jemalloc triggers intractable runtime
 hang/error/symbolizer issue; locally -O1 makes it okay with clang-17.  It is
 a Hail Mary.  Also: Added core-C[XX]FLAGS override to Conan recipe and using
 it for this -O1 overriding (previous attempt to do it quick-and-dirty failed,
 as the core setting from CMake appears later on command line and overrides
 build.tools settings if in conflict.  Removed a DeathTest from gtest
 exclusions with TSAN, as this is a problem only without -DNDEBUG (locally I
 was running without it hence seeing problem locally and becoming paranoid
 about workflow too).

---
 .github/workflows/main.yml | 31 ++++++++++++++++++++-----------
 conanfile.py               | 16 ++++++++++++++++
 2 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index f13bd3c35..0aa57378a 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -215,21 +215,20 @@ jobs:
             # While UBSAN might work with LTO, I do not want the aggravation/entropy.  Turn it off.
             # Plus inheriting from regular RelWithDebInfo anyway.
             no-lto: true
-          # XXX trying -O1 for less craziness
           - id: relwithdebinfo-tsan
             conan-profile-build-type: RelWithDebInfo
             conan-profile-jemalloc-build-type: Release
             conan-profile-custom-conf: |
-              tools.build:cflags = ["-fsanitize=thread -O1"]
-              tools.build:cxxflags = ["-fsanitize=thread -O1"]
-              tools.build:sharedlinkflags = ["-fsanitize=thread -O1"]
-              tools.build:exelinkflags = ["-fsanitize=thread -O1"]
+              tools.build:cflags = ["-fsanitize=thread"]
+              tools.build:cxxflags = ["-fsanitize=thread"]
+              tools.build:sharedlinkflags = ["-fsanitize=thread"]
+              tools.build:exelinkflags = ["-fsanitize=thread"]
             conan-profile-custom-settings: |
               compiler.sanitizer = thread
             conan-profile-custom-buildenv: |
-              CXXFLAGS = -fsanitize=thread -O1
-              CFLAGS = -fsanitize=thread -O1
-              LDFLAGS = -fsanitize=thread -O1
+              CXXFLAGS = -fsanitize=thread
+              CFLAGS = -fsanitize=thread
+              LDFLAGS = -fsanitize=thread
             conan-custom-settings-defs: |
               data['compiler']['gcc']['sanitizer'] = ['None', 'address', 'thread', 'memory', 'undefined']
               data['compiler']['clang']['sanitizer'] = ['None', 'address', 'thread', 'memory', 'undefined']
@@ -248,14 +247,21 @@ jobs:
               Borrower_shm_pool_collection_test.Multiprocess:\
               Shm_pool_collection_test.Interface:\
               Shm_pool_collection_test.Multiprocess:\
-              Shm_session_data_test.Multithread_object_database:\
-              Jemalloc_shm_pool_collection_DeathTest.Interface
+              Shm_session_data_test.Multithread_object_database
             sanitizer-name: tsan
             # While TSAN might work with LTO, I do not want the aggravation/entropy.  Turn it off.
             # Also, for some clangs, there are TSAN WARNINGs at times about too-small symbolizer buffer or something;
             # throwing LTO into the mix seems like unnecessary entropy.
             # Plus inheriting from regular RelWithDebInfo anyway.
             no-lto: true
+            # This hack replaces the default CMake value (for RelWithDebInfo), which is -O2 -g -DNDEBUG.
+            # TSAN, at least, displays some crashing/hanging instability with things like
+            #   LLVM ERROR: Sections with relocations should have an address of 0
+            #   PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
+            # otherwise.  -O1 seems to avoid this fate.  TODO: This is a hack and not super-nice in terms of realism
+            # and other considerations; but given that the alternative is an unreliable catastrophe -- with TSAN
+            # being officially in beta in clang at least -- it is preferable.  Revisit (there's a ticket).
+            build-type-cflags-override: -O1 -g -DNDEBUG
           - id: relwithdebinfo-msan
             conan-profile-build-type: RelWithDebInfo
             conan-profile-jemalloc-build-type: Release
@@ -508,9 +514,12 @@ jobs:
         ipc:doc = False
         ipc:build = True
         EOF
-        if [ "${{ matrix.build-test-cfg.no-lto }}" != '' ]; then
+        if [ "${{ matrix.build-test-cfg.no-lto }}" != '' ] && [ "${{ matrix.build-test-cfg.no-lto }}" != 'false' ]; then
           echo 'ipc:build_no_lto = True' >> conan_profile
         fi
+        if [ "${{ matrix.build-test-cfg.build-type-cflags-override }}" != '' ]; then
+          echo 'ipc:build_type_cflags_override = ${{ matrix.build-test-cfg.build-type-cflags-override }}' >> conan_profile
+        fi
 
     # We need to prepare a sanitizer ignore-list in MSAN mode.  Background for this is subtle and annoying:
     # As it stands, whatever matrix compiler/build-type is chosen applies not just to our code (correct)
diff --git a/conanfile.py b/conanfile.py
index 241470ca2..6f7439622 100644
--- a/conanfile.py
+++ b/conanfile.py
@@ -9,12 +9,22 @@ class IpcRecipe(ConanFile):
     options = {
         "build": [True, False],
         "build_no_lto": [True, False],
+        # Replaces the core C/C++ compiler flags (not linker flags) for the chosen settings.build_type.
+        # Note that these appear *after* any C[XX]FLAGS and tools.build.c[xx]flags
+        # on the compiler command line, so it would not be
+        # sufficient to instead add the desired flags to tools.build* or *FLAGS, as if a setting in
+        # the core CMake-chosen flags conflicts with one of those, the core one wins due to being last on command
+        # line.  Long story short, this is for the core flags, typically: -O<something> [-g] [-DNDEBUG].
+        # So default for, e.g., RelWithDebInfo in Linux = -O2 -g -DNDEBUG; and one could set
+        # this option to "-O3 -g -DNDEBUG" to increase the optimization level.
+        "build_type_cflags_override": "ANY",
         "doc": [True, False],
     }
 
     default_options = {
         "build": True,
         "build_no_lto": False,
+        "build_type_cflags_override": "",
         "doc": False,
     }
 
@@ -26,6 +36,7 @@ def configure(self):
     def generate(self):
         deps = CMakeDeps(self)
         if self.options.doc:
+            # TODO: This magic version number is repeated several times.  Code reuse.
             deps.build_context_activated = ["doxygen/1.9.4"]
         deps.generate()
 
@@ -38,6 +49,11 @@ def generate(self):
         if self.options.doc:
             toolchain.variables["CFG_ENABLE_DOC_GEN"] = "ON"
             toolchain.variables["CFG_SKIP_CODE_GEN"] = "ON"
+        if self.options.build_type_cflags_override:
+            suffix = str(self.settings.build_type).upper()
+            toolchain.variables["CMAKE_CXX_FLAGS_" + suffix] = self.options.build_type_cflags_override
+            toolchain.variables["CMAKE_C_FLAGS_" + suffix] = self.options.build_type_cflags_override
+
         toolchain.generate()
 
     def build(self):

From edbe32a76bfc367fd8ab495cc5b7bbc4f64b8072 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 14:51:31 -0800
Subject: [PATCH 03/23] Updating submodules.  Deleting suppressions file
 accidentally left behind (it has been moved into ipc_shm_arena_lend
 conceptually).

---
 flow                                                  |  2 +-
 ipc_core                                              |  2 +-
 ipc_session                                           |  2 +-
 ipc_shm                                               |  2 +-
 ipc_shm_arena_lend                                    |  2 +-
 ipc_transport_structured                              |  2 +-
 .../shm-j/sanitize/tsan/suppressions_clang.cfg        | 11 -----------
 7 files changed, 6 insertions(+), 17 deletions(-)
 delete mode 100644 test/suite/transport_test/shm-j/sanitize/tsan/suppressions_clang.cfg

diff --git a/flow b/flow
index df3bead9b..b9ef34d91 160000
--- a/flow
+++ b/flow
@@ -1 +1 @@
-Subproject commit df3bead9b3796330f7555b4f239f17ce7336e4d3
+Subproject commit b9ef34d913486feafa4b547f9d33b5358d7c8db6
diff --git a/ipc_core b/ipc_core
index f278e699e..1ebe54b3b 160000
--- a/ipc_core
+++ b/ipc_core
@@ -1 +1 @@
-Subproject commit f278e699e8188251a1ec187e3285c2c9cbd4073b
+Subproject commit 1ebe54b3b551bb57c51768bd1d4ad51aeb2ddb97
diff --git a/ipc_session b/ipc_session
index 4c5d8cc10..16fd0581e 160000
--- a/ipc_session
+++ b/ipc_session
@@ -1 +1 @@
-Subproject commit 4c5d8cc10c205ebe1bfa4a41c32c4db174578ba9
+Subproject commit 16fd0581e5012af015857dea0bf1af6cfb95c9e7
diff --git a/ipc_shm b/ipc_shm
index 9fd99e94a..147e4b52e 160000
--- a/ipc_shm
+++ b/ipc_shm
@@ -1 +1 @@
-Subproject commit 9fd99e94a657a834fc58a82b5116c319e33b3a1c
+Subproject commit 147e4b52ea6e83d739f989289bde6a9f6d668a14
diff --git a/ipc_shm_arena_lend b/ipc_shm_arena_lend
index 277de175b..c1b9c37c8 160000
--- a/ipc_shm_arena_lend
+++ b/ipc_shm_arena_lend
@@ -1 +1 @@
-Subproject commit 277de175b557acf2f3628225a94ce6bf88d82712
+Subproject commit c1b9c37c81f66e04c08752fb62eef7f2a1b0373a
diff --git a/ipc_transport_structured b/ipc_transport_structured
index 4fb1fa2dc..78745321b 160000
--- a/ipc_transport_structured
+++ b/ipc_transport_structured
@@ -1 +1 @@
-Subproject commit 4fb1fa2dca9e9969d3db9c47cea6714f4d9294a0
+Subproject commit 78745321b5216df8b2464714acb1f5affceb860e
diff --git a/test/suite/transport_test/shm-j/sanitize/tsan/suppressions_clang.cfg b/test/suite/transport_test/shm-j/sanitize/tsan/suppressions_clang.cfg
deleted file mode 100644
index fb24c43f8..000000000
--- a/test/suite/transport_test/shm-j/sanitize/tsan/suppressions_clang.cfg
+++ /dev/null
@@ -1,11 +0,0 @@
-# This is for transport_test exercise mode SHM-jemalloc sub-mode.
-# In clang-15+ at least TSAN has a clean run except for warnings of the type:
-#   SUMMARY: ThreadSanitizer: data race .../src/include/jemalloc/internal/extent_inlines.h:285:17 in extent_...
-# The extent_ function varies, but in all cases it's in a subtree of a `je_arena*()` call; this is inside
-# jemalloc.  I (ygoldfel) have filed a ticket regarding confirming this (as on the topic of SHM-jemalloc I am not
-# the #1 subject matter expert), but IMO: this is very low-level code in the guts of jemalloc, and jemalloc is
-# generally safe w/r/t concurrent calls; so most likely TSAN cannot follow what is going on.  Also similar
-# warnings are observed in unit_test (and a colleague suppressed je_arena* for it similarly).  So:
-# probably it is a false positive; but ticket has been filed to confirm; in the meantime confidence in TSAN
-# coverage (with these suppressions) is high (on my part at least).
-race:je_arena*

From 38182675a154088435c0b77692cde2af3bcb4b9e Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 14:53:38 -0800
Subject: [PATCH 04/23] Adding obscure TSAN suppression for transpot_test
 ex/heap mode/sub-mode.

---
 .../heap/sanitize/tsan/suppressions_clang.cfg | 66 +++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 test/suite/transport_test/heap/sanitize/tsan/suppressions_clang.cfg

diff --git a/test/suite/transport_test/heap/sanitize/tsan/suppressions_clang.cfg b/test/suite/transport_test/heap/sanitize/tsan/suppressions_clang.cfg
new file mode 100644
index 000000000..7c2f76141
--- /dev/null
+++ b/test/suite/transport_test/heap/sanitize/tsan/suppressions_clang.cfg
@@ -0,0 +1,66 @@
+# This is for transport_test exercise mode heap sub-mode.
+
+# I have seen this warning exactly once as of this writing, with clang-15.  Upon careful analysis: it's got to be
+# a false positive.  It looks like this:
+#   WARNING: ThreadSanitizer: data race (pid=75301)
+#     Write of size 8 at 0x7ba8000006f0 by thread T79:
+#       #0 close <null> (ex_srv.exec+0xa71c5)
+#       #1 boost::asio::detail::eventfd_select_interrupter::close_descriptors()
+#          .../include/boost/asio/detail/impl/eventfd_select_interrupter.ipp:106:5 (ex_srv.exec+0x1684e1)
+#       #2 boost::asio::detail::eventfd_select_interrupter::~eventfd_select_interrupter()
+#          .../include/boost/asio/detail/impl/eventfd_select_interrupter.ipp:98:3 (ex_srv.exec+0x1684e1)
+#       #3 boost::asio::detail::epoll_reactor::~epoll_reactor()
+#          .../include/boost/asio/detail/impl/epoll_reactor.ipp:72:1 (ex_srv.exec+0x1684e1)
+#       #4 boost::asio::detail::epoll_reactor::~epoll_reactor()
+#          .../include/boost/asio/detail/impl/epoll_reactor.ipp:67:1 (ex_srv.exec+0x168525)
+#       ...
+#       #16 ipc::transport::sync_io::Native_socket_stream::operator=(ipc::transport::sync_io::Native_socket_stream&&)
+#          /home/runner/work/ipc/ipc/ipc_core/src/ipc/transport/sync_io/native_socket_stream.cpp:36:77 (ex_srv.exec+0xd14d14)
+#       #17 ipc::session::Server_session_impl<...>::create_channel_and_resources(...)::'lambda'()::operator()() const
+#          /home/runner/work/ipc/ipc/ipc_session/src/ipc/session/detail/server_session_impl.hpp:1302:28 (ex_srv.exec+0x2ae130)
+#       ...
+#     Previous read of size 8 at 0x7ba8000006f0 by thread T2 (mutexes: write M0):
+#       #0 epoll_ctl <null> (ex_srv.exec+0xa8086)
+#       #1 boost::asio::detail::epoll_reactor::deregister_descriptor(int, boost::asio::detail::epoll_reactor::descriptor_state*&, bool)
+#          .../include/boost/asio/detail/impl/epoll_reactor.ipp:403:7 (ex_srv.exec+0x18a89e)
+#       #2 boost::asio::detail::reactive_descriptor_service::release(boost::asio::detail::reactive_descriptor_service::implementation_type&) .../include/boost/asio/detail/impl/reactive_descriptor_service.ipp:174:14 (ex_srv.exec+0x18f816)
+#       #3 boost::asio::posix::basic_descriptor<boost::asio::any_io_executor>::release()
+#          .../include/boost/asio/posix/basic_descriptor.hpp:381:32 (ex_srv.exec+0x18f816)
+#       #4 ipc::util::sync_io::Asio_waitable_native_handle::~Asio_waitable_native_handle()
+#          /home/runner/work/ipc/ipc/ipc_core/src/ipc/util/sync_io/asio_waitable_native_hndl.cpp:53:3 (ex_srv.exec+0xd1f805)
+#       #5 ipc::transport::sync_io::Native_socket_stream::Impl::~Impl()
+#          /home/runner/work/ipc/ipc/ipc_core/src/ipc/transport/sync_io/detail/native_socket_stream_impl.cpp:197:1 (ex_srv.exec+0xd4e7f5)
+#       ...
+#       #34 ipc::transport::test::Ex_srv<...>::App_session::~App_session()
+#          /home/runner/work/ipc/ipc/test/suite/transport_test/ex_srv.hpp:64:9 (ex_srv.exec+0x26fcd2)
+#       ...
+#     Location is file descriptor 74 created by thread T79 at:
+#       #0 eventfd <null> (ex_srv.exec+0xa66cc)
+#       #1 boost::asio::detail::eventfd_select_interrupter::open_descriptors()
+#          .../include/boost/asio/detail/impl/eventfd_select_interrupter.ipp:59:5 (ex_srv.exec+0x169545)
+#       ...
+#       #20 ipc::transport::sync_io::Native_socket_stream::Native_socket_stream()
+#          /home/runner/work/ipc/ipc/ipc_core/src/ipc/transport/sync_io/native_socket_stream.cpp:55:3 (ex_srv.exec+0xd14e3e)
+#       #21 ipc::session::Server_session_impl<...>::create_channel_and_resources(...)
+#          /home/runner/work/ipc/ipc/ipc_session/src/ipc/session/detail/server_session_impl.hpp:1275:24 (ex_srv.exec+0x2aba3e)
+#       ...
+#     Thread T79 '0x7b7c00012600]' (tid=75474, running) created by thread T5 at:
+#       ...
+#     Thread T2 'guy' (tid=75305, running) created by main thread at:
+#       ...
+#   SUMMARY: ThreadSanitizer: data race (/home/runner/bin/ex_srv.exec+0xa71c5) in close
+# It is worried this FD is being close()d -- after *just* being created (synchronously even!) in that same thread,
+# within Server_session_impl::create_channel_and_resources() -- which indeed happens: a blank Native_socket_stream,
+# with an unused Task_engine (boost::asio::io_context), including its epoll FD, is quickly replaced by a real one
+# storing a native handle from a ::socketpair() call; so the io_context+FD is created/opened and destroyed/closed.
+# The thread is that session's Server_session_impl m_async_worker.  It thinks that same FD was being messed with in a
+# different thread -- namely 'guy' (from Ex_srv test class) -- when it was epoll_ctl()ed.  But that was a different
+# Server_session_impl which was just closed.  It might be the same FD, numerically, but it was closed and then
+# opened again; there is plenty of synchronization between those unrelated operations.  Not sure why TSAN got confused;
+# would need to understand its algorithm in more detail; but I (ygoldfel) know this particular code quite well; it
+# doesn't make sense to me that this is unsynchronized access to the same FD.
+# TODO: Try to reproduce and debug.  Won't be easy; again I've only seen it once.  Do note that the test completed
+# fine even then (but that doesn't in itself prove there's no race of course).
+#
+# In the meantime suppress the issue at a few frames up from the reported problem.  Hopefully that takes care of it.
+race:^boost::asio::detail::epoll_reactor::~epoll_reactor$

From ad3c5784cd6d1aee5056cc1d1f065bd30272cfbe Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 14:55:21 -0800
Subject: [PATCH 05/23] Adding obscure TSAN suppression for transport_test
 ex/heap mode/sub-mode. (part deux)

---
 .github/workflows/main.yml | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 0aa57378a..a864b0547 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -794,24 +794,22 @@ jobs:
         # Script created by pipeline during job.
         echo "Log level: [$1]."
         echo "Exercise sub-mode: [$2]."
-        echo "Sub-mode snippet (none or 'shm-?'): [$3]."
+        echo "Sub-mode snippet (none or '-shm-?'): [$3]."
         OUT_DIR=${{ env.install-dir }}/bin/logs/transport_test/exercise/$2
         mkdir -p $OUT_DIR
         SUPP_DIR_A=${{ github.workspace }}/flow/src
-        { cat $SUPP_DIR_A/${{ env.san-suppress-cfg-in-file1 }} $SUPP_DIR_A/${{ env.san-suppress-cfg-in-file2 }} \
-            > ${{ env.san-suppress-cfg-file }} 2> /dev/null; } || true
         if [ "$3" == '-shm-j' ]; then
-          # SHM-jemalloc mode => jemalloc is in fact exercised => suppress jemalloc stuff.  (UBSAN, TSAN)
+          # SHM-jemalloc mode => jemalloc is in fact exercised => suppress libjemalloc stuff.
+          # But, nicely, no transport_test-specific suppressions needed as of this writing.
           SUPP_DIR_B=${{ github.workspace }}/ipc_shm_arena_lend/src
-          { cat $SUPP_DIR_B/${{ env.san-suppress-cfg-in-file1 }} $SUPP_DIR_B/${{ env.san-suppress-cfg-in-file2 }} \
-              >> ${{ env.san-suppress-cfg-file }} 2> /dev/null; } || true
         elif [ "$3" == '-shm-c' ]; then
-          # SHM-classic mode => TSAN gets confused by opposing process (e.g., client) allocating while current process
-          # (e.g., accordingly, server) deallocates => false-positives when accessing SHM-mapped areas.  (TSAN)
           SUPP_DIR_B=${{ github.workspace }}/test/suite/transport_test/shm-c
-          { cat $SUPP_DIR_B/${{ env.san-suppress-cfg-in-file1 }} $SUPP_DIR_B/${{ env.san-suppress-cfg-in-file2 }} \
-              >> ${{ env.san-suppress-cfg-file }} 2> /dev/null; } || true
+        else # if [ "$3" == '' ]; then
+          SUPP_DIR_B=${{ github.workspace }}/test/suite/transport_test/heap
         fi
+        { cat $SUPP_DIR_A/${{ env.san-suppress-cfg-in-file1 }} $SUPP_DIR_A/${{ env.san-suppress-cfg-in-file2 }} \
+              $SUPP_DIR_B/${{ env.san-suppress-cfg-in-file1 }} $SUPP_DIR_B/${{ env.san-suppress-cfg-in-file2 }} \
+            > ${{ env.san-suppress-cfg-file }} 2> /dev/null; } || true
         ${{ env.setup-tests-env }}
         ~/bin/ex_srv.exec exercise-srv$3 $OUT_DIR/srv.log info $1 \
           > $OUT_DIR/srv.console.log 2>&1 &

From 85a96425d46cd5c09900d7653567e2e29b297925 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 14:56:27 -0800
Subject: [PATCH 06/23] The -O1 experiment for TSAN clang-17 problem with
 transport_test ex/SHM-jemalloc did not work; so undoing it to at least reduce
 entropy.

---
 .github/workflows/main.yml | 8 --------
 conanfile.py               | 3 +++
 2 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index a864b0547..63ca32626 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -254,14 +254,6 @@ jobs:
             # throwing LTO into the mix seems like unnecessary entropy.
             # Plus inheriting from regular RelWithDebInfo anyway.
             no-lto: true
-            # This hack replaces the default CMake value (for RelWithDebInfo), which is -O2 -g -DNDEBUG.
-            # TSAN, at least, displays some crashing/hanging instability with things like
-            #   LLVM ERROR: Sections with relocations should have an address of 0
-            #   PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
-            # otherwise.  -O1 seems to avoid this fate.  TODO: This is a hack and not super-nice in terms of realism
-            # and other considerations; but given that the alternative is an unreliable catastrophe -- with TSAN
-            # being officially in beta in clang at least -- it is preferable.  Revisit (there's a ticket).
-            build-type-cflags-override: -O1 -g -DNDEBUG
           - id: relwithdebinfo-msan
             conan-profile-build-type: RelWithDebInfo
             conan-profile-jemalloc-build-type: Release
diff --git a/conanfile.py b/conanfile.py
index 6f7439622..e5eee74ce 100644
--- a/conanfile.py
+++ b/conanfile.py
@@ -17,6 +17,9 @@ class IpcRecipe(ConanFile):
         # line.  Long story short, this is for the core flags, typically: -O<something> [-g] [-DNDEBUG].
         # So default for, e.g., RelWithDebInfo in Linux = -O2 -g -DNDEBUG; and one could set
         # this option to "-O3 -g -DNDEBUG" to increase the optimization level.
+        #
+        # This affects `ipc` CMake only; meaning flow, ipc_*, ipc objects will have this overridden; while
+        # Boost libs, jemalloc lib, capnp/kj libs will build how they would've built anyway.
         "build_type_cflags_override": "ANY",
         "doc": [True, False],
     }

From 5685a65f7d1c4423e1634c8fcc618925c62e5047 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 14:57:28 -0800
Subject: [PATCH 07/23] Since it did not work, no real choice but to skip that
 particular test with TSAN with that particular compiler clang-17.  It will
 still run with clang-15/16.

---
 .github/workflows/main.yml | 40 ++++++++++++++++++++++++++++++++++----
 1 file changed, 36 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 63ca32626..453d26e7e 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -299,9 +299,14 @@ jobs:
         #     So this status quo is pretty good.  TODO: Do the work/get MSAN functional/useful; un-exclude it then.
         #   - *SAN with gcc: We concentrate on clang sanitizers; they are newer/nicer; having to worry about differences
         #     between them is an excessive burden.  So excluding gcc ASAN/UBSAN/TSAN.
-        #     - TODO: Consider reducing to the newest clang.  Generally they just keep improving; the chances of
-        #       something being uncaught (incorrectly) with a later version are slim.  Not impossible though.  Look
-        #       into it.
+        #     - TODO: Consider reducing to the newest or most stable clang.  Generally they just keep improving; the
+        #       chances of something being uncaught (incorrectly) with a later version are slim.  Not impossible though.
+        #       Look into it.  Update: As of this writing transport_test exercise mode/SHM-jemalloc sub-mode is
+        #       disabled for TSAN clang-17 due to instability of TSAN itself.  So clearly when it comes to TSAN
+        #       (which is officially in beta as of clang-17), higher version does not mean everything is better.
+        #       Hence perhaps this to-do is more of a longer-term thing, when all the sanitizers stabilize, or when
+        #       we find a single very-stable config.  Just remember we aren't testing the sanitizer or our code's
+        #       ability to be sanitized; we just want to detect any problems in the code -- however we get there.
         #   - *SAN with clang-13 (but not 15+): As of this writing clang-13 produces some additional warnings,
         #     at least in TSAN, which appear to be related to nearby non-race messages like
         #     `==75454==WARNING: Symbolizer buffer too small`.  As a result, we either have to eliminate the
@@ -851,10 +856,37 @@ jobs:
           ${{ env.install-dir }}/bin/run_transport_test_ex.sh \
           data shm_classic_log_level_data -shm-c
 
+    # Disabling this particular test run for the specific case of clang-17 in TSAN (thread sanitizer) config
+    # (in particular at least 2 other clangs+TSAN are exercised, so the TSAN coverage is still good).
+    # First the reason in detail: This run always fails at this point in the server binary:
+    #   2023-12-20 11:36:11.322479842 +0000 [info]: Tguy: ex_srv.hpp:send_req_b(1428): App_session [0x7b3800008180]:
+    #     Chan B[0]: Filling/send()ing payload (description = [reuse out-message + SHM-handle to modified (unless
+    #     SHM-jemalloc) existing STL data]; alt-payload? = [0]; reusing msg? = [1]; reusing SHM payload? = [1]).
+    #   LLVM ERROR: Sections with relocations should have an address of 0
+    #   PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
+    #   Stack dump:
+    #   0.  Program arguments: /usr/bin/llvm-symbolizer-17 --demangle --inlines --default-arch=x86_64
+    #   Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
+    #   ...
+    #   ==77990==WARNING: Can't read from symbolizer at fd 599
+    #   2023-12-20 11:36:31.592293322 +0000 [info]: Tguy: ex_srv.hpp:send_req_b(1547): App_session [0x7b3800008180]: Chan B[0]: Filling done.  Now to send.
+    # Sometimes the exact point is different, depending on timing; but in any case it is always the above
+    # TSAN/LLVM error, at which point the thread gets stuck for a long time (10+ seconds); but eventually gets
+    # unstuck; however transport_test happens to be testing a feature in a certain way so that a giant blocking
+    # operation in this thread delays certain processing, causes an internal timeout, and the test exits/fails.
+    # Sure, we could make some changes to the test for that to not happen, but that's beside the point: TSAN
+    # at run-time is trying to do something and fails terribly; I have no wish to try to work around that situation;
+    # literally it says "PLEASE submit a bug report [to clang devs]."
+    #
+    # TODO: Revisit; figure out how to not trigger this; re-enable.  For the record, I (ygoldfel) cannot reproduce
+    # in a local clang-17, albeit with libc++ (LLVM STL) instead of libstdc++ (GNU STL).  I've also tried to
+    # reduce optimization to -O1, as well as with and without LTO; same result.
     - name: Run integration test [transport_test - Exercise mode - SHM-jemalloc sub-mode]
       id: transport_test_ex_shm_j
       if: |
-        !cancelled()
+        (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
+                             &&
+                             (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan')))
       run: |
         /usr/bin/bash -e \
           ${{ env.install-dir }}/bin/run_transport_test_ex.sh \

From 82048353bb6b0bd4c7b36edf8587fd9ca31d9577 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 14:58:48 -0800
Subject: [PATCH 08/23] More narrow suppression syntax.

---
 .../shm-c/sanitize/tsan/suppressions_clang.cfg       |  8 ++++----
 .../unit_test/sanitize/tsan/suppressions_clang.cfg   | 10 +++++-----
 .../sanitize/tsan/suppressions_clang_15.cfg          | 12 ++++++------
 .../sanitize/tsan/suppressions_clang_16.cfg          |  8 ++++----
 .../sanitize/tsan/suppressions_clang_17.cfg          |  6 +++---
 5 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/test/suite/transport_test/shm-c/sanitize/tsan/suppressions_clang.cfg b/test/suite/transport_test/shm-c/sanitize/tsan/suppressions_clang.cfg
index 22b03ad14..5a0d7bb3e 100644
--- a/test/suite/transport_test/shm-c/sanitize/tsan/suppressions_clang.cfg
+++ b/test/suite/transport_test/shm-c/sanitize/tsan/suppressions_clang.cfg
@@ -23,12 +23,12 @@
 # we've specifically seen -- but not too much more.
 
 # offset_ptr used (in our context at least) only for SHM work, so catch anything in its code: will be false-positive.
-race:boost::interprocess::offset_ptr<*
+race:^boost::interprocess::offset_ptr<
 # Similarly anything capnp-generated or from libcapnp like the following would be in SHM.  (Actually the
 # session master channel does non-SHM capnp, so there are some things in non-SHM; but those things are TSAN sans
 # suppression in heap sub-mode at least.  So it's not so bad to include it in these suppressions.)  Again catch
 # anything in there as false positive.
-race:capnp::_::*
+race:^capnp::_::
 
 # There are common warnings from flow::util::Basic_blob<Stateless_allocator<...>>: in size(), in begin(), others.
 # In every case it's access to a SHM-oriented allocator-parameterized Basic_blob, which is a container type.
@@ -36,11 +36,11 @@ race:capnp::_::*
 # string<>, list<>, etc.  In all cases however they'll be shm::stl::Stateless_allocator-parameterized, and in all
 # cases of the latter it is access to SHM.  So it should be ideal to just mention that allocator and wildcard the
 # rest.
-race:*ipc::shm::stl::Stateless_allocator<*
+race:ipc::shm::stl::Stateless_allocator<
 
 # This is a little too specific for my tastes -- but on the other hand just `boost::intrusive::*` might catch some
 # non-false-positive warning, theoretically, in non-SHM work.  Until we see a false positive in boost::intrusive
 # that's not this, let's just suppress the exact false positive we have in fact seen.
-race:boost::intrusive::detail::size_holder<true, unsigned long, void>::get_size
+race:^boost::intrusive::detail::size_holder<true, unsigned long, void>::get_size$
 
 # (End SHM-related suppressions.)
diff --git a/test/suite/unit_test/sanitize/tsan/suppressions_clang.cfg b/test/suite/unit_test/sanitize/tsan/suppressions_clang.cfg
index b2ba51ff9..d3bdf05fc 100644
--- a/test/suite/unit_test/sanitize/tsan/suppressions_clang.cfg
+++ b/test/suite/unit_test/sanitize/tsan/suppressions_clang.cfg
@@ -1,9 +1,9 @@
 # Current version assumption: clang-15/16/17.
 
 # TODO: Explain these in detail.
-race:ipc::shm::arena_lend::Borrower_shm_pool_collection::open_shm_pool
-race:ipc::session::shm::arena_lend::Shm_session_data::register_borrower_collection
-race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::~Test_client
-race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Object_event_listener::notify_object_received
-race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Object_event_listener::~Object_event_listener
+race:^ipc::shm::arena_lend::Borrower_shm_pool_collection::open_shm_pool$
+race:^ipc::session::shm::arena_lend::Shm_session_data::register_borrower_collection$
+race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::~Test_client$
+race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Object_event_listener::notify_object_received$
+race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Object_event_listener::~Object_event_listener$
 # (End TODO.)
diff --git a/test/suite/unit_test/sanitize/tsan/suppressions_clang_15.cfg b/test/suite/unit_test/sanitize/tsan/suppressions_clang_15.cfg
index 96f437bf8..544ec2730 100644
--- a/test/suite/unit_test/sanitize/tsan/suppressions_clang_15.cfg
+++ b/test/suite/unit_test/sanitize/tsan/suppressions_clang_15.cfg
@@ -1,8 +1,8 @@
 # TODO: Explain these in detail.
-race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::open_app_channel
-race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client_manager::Client_data::~Client_data
-race:ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server_executor::many_objects_creator_functor
-race:ipc::test::Test_logger::Test_logger
-race:ipc::util::sync_io::Timer_event_emitter::Timer_event_emitter
-race:ipc::session::shm::arena_lend::Borrower_shm_pool_collection_repository::register_shm_pool
+race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::open_app_channel$
+race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client_manager::Client_data::~Client_data$
+race:^ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server_executor::many_objects_creator_functor$
+race:^ipc::test::Test_logger::Test_logger$
+race:^ipc::util::sync_io::Timer_event_emitter::Timer_event_emitter$
+race:^ipc::session::shm::arena_lend::Borrower_shm_pool_collection_repository::register_shm_pool$
 # (End TODO.)
diff --git a/test/suite/unit_test/sanitize/tsan/suppressions_clang_16.cfg b/test/suite/unit_test/sanitize/tsan/suppressions_clang_16.cfg
index 82ecc0ad8..36a879209 100644
--- a/test/suite/unit_test/sanitize/tsan/suppressions_clang_16.cfg
+++ b/test/suite/unit_test/sanitize/tsan/suppressions_clang_16.cfg
@@ -1,6 +1,6 @@
 # TODO: Explain these in detail.
-race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::open_app_channel
-race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client_manager::~Test_client_manager
-race:ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server::execute_allocation_performance_tests
-race:ipc::util::sync_io::Timer_event_emitter::Timer_event_emitter
+race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::open_app_channel$
+race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client_manager::~Test_client_manager$
+race:^ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server::execute_allocation_performance_tests$
+race:^ipc::util::sync_io::Timer_event_emitter::Timer_event_emitter$
 # (End TODO.)
diff --git a/test/suite/unit_test/sanitize/tsan/suppressions_clang_17.cfg b/test/suite/unit_test/sanitize/tsan/suppressions_clang_17.cfg
index 4c4792430..9ec5d0c5f 100644
--- a/test/suite/unit_test/sanitize/tsan/suppressions_clang_17.cfg
+++ b/test/suite/unit_test/sanitize/tsan/suppressions_clang_17.cfg
@@ -1,5 +1,5 @@
 # TODO: Explain these in detail.
-race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Basic_event_listener::~Basic_event_listener
-race:ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server_executor::many_objects_creator_functor
-race:ipc::test::Test_logger::Test_logger
+race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Basic_event_listener::~Basic_event_listener$
+race:^ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server_executor::many_objects_creator_functor$
+race:^ipc::test::Test_logger::Test_logger$
 # (End TODO.)

From 3d3f1c28700c3ef53d89f219115b3e4343196e16 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 14:59:26 -0800
Subject: [PATCH 09/23] Add the info/TODO regarding how sanitizer/etc. settings
 spread to some things we probably do not want necessarily.

---
 .github/workflows/main.yml | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 453d26e7e..b6cc278d0 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -481,6 +481,32 @@ jobs:
           yaml.dump(data, file)
         "
 
+    # Important info/somewhat important TODO: The C[XX]FLAGS and linker-flags are supplied via
+    # ${{ matrix.build-test-cfg.conan-profile-custom-conf }} and
+    # ${{ matrix.build-test-cfg.conan-profile-custom-buildenv }}.  These affect not just our objects/libs/executables;
+    # but also at least: 3rd party libs (jemalloc, capnp/kj, boost, gtest), 3rd party executables
+    # (capnp compiler binary; temp binaries created by auto-tools configure scripts to test features).
+    # In the case of the libs that's usually good; in particular things like
+    # -fsanitize=address (ASAN) (for build-type relwithdebinfo-asan) ideally are applied to all built code
+    # uniformly.  (There are other libs being built, one can see: at least openssl and zlib; they're not really
+    # involved in our actual product, at least not in a core way, so for those it arguably matters less either way.)
+    # In the case of the binaries it is usually bad; we want the fastest, most normal tools possible, not ones
+    # built weirdly with whatever settings we're trying to test with our own software.  For one it makes those
+    # tools slower -- perhaps not the hugest deal in practice here -- but it also generally increases entropy; and
+    # it has also resulted in various pain:
+    #   - Cannot use -fno-sanitize-recover with UBSAN (abort program on warning) if we wanted to: it causes some
+    #     hidden configure-script-generated binary abort => capnp binary build fails.
+    #   - capnp binary fails MSAN at startup; hence capnp-compilation of our .capnp schemas fails.
+    # We have worked around all these, so the thing altogether works.  It's just somewhat odd and entropy-ridden;
+    # and might cause maintanability problems over time, as it has already in the past.
+    # The TODO is to be more judicious about it
+    # and only apply these things to the libs/executables we want it applied.  It is probably not so simple;
+    # but worst-case it should be possible to use something like build-type-cflags-override to target our code;
+    # and per-recipe (Boost, jemalloc, gtest...) techniques to target others; and not use the aggressive
+    # conan-profile-custom-conf and conan-profile-custom-buildenv.  That said, there will be interesting subtleties
+    # like: libcapnp/kj are linked into capnp compiler binary; *and* to our code.  So we should instrument it with
+    # sanitizer (when applicable); now some of the capnp-compiler-binary is instrumented; some isn't.  Would that
+    # work, or would it be better to build capnp twice then (once for the binary, once for the linked libraries)?
     - name: Create Conan profile
       run: |
         cat <<'EOF' > conan_profile

From 1b16363ef2df81d5429e6e76aa0e764b7b5fcff1 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 16:14:53 -0800
Subject: [PATCH 10/23] Suppression tweak.

---
 flow                                            |  2 +-
 ipc_shm_arena_lend                              |  2 +-
 .../heap/sanitize/tsan/suppressions_clang.cfg   |  7 ++++++-
 .../shm-c/sanitize/tsan/suppressions_clang.cfg  |  2 ++
 .../sanitize/tsan/suppressions_clang.cfg        | 13 ++++++++-----
 .../sanitize/tsan/suppressions_clang_15.cfg     | 17 +++++++++++------
 .../sanitize/tsan/suppressions_clang_16.cfg     | 13 +++++++++----
 .../sanitize/tsan/suppressions_clang_17.cfg     | 11 ++++++++---
 8 files changed, 46 insertions(+), 21 deletions(-)

diff --git a/flow b/flow
index b9ef34d91..616b06a26 160000
--- a/flow
+++ b/flow
@@ -1 +1 @@
-Subproject commit b9ef34d913486feafa4b547f9d33b5358d7c8db6
+Subproject commit 616b06a2663cb2838cff9875dea6d42ed3e505f3
diff --git a/ipc_shm_arena_lend b/ipc_shm_arena_lend
index c1b9c37c8..f21975e27 160000
--- a/ipc_shm_arena_lend
+++ b/ipc_shm_arena_lend
@@ -1 +1 @@
-Subproject commit c1b9c37c81f66e04c08752fb62eef7f2a1b0373a
+Subproject commit f21975e2720a6b5712d7a72b942d2f516b1f8e9b
diff --git a/test/suite/transport_test/heap/sanitize/tsan/suppressions_clang.cfg b/test/suite/transport_test/heap/sanitize/tsan/suppressions_clang.cfg
index 7c2f76141..2c859002f 100644
--- a/test/suite/transport_test/heap/sanitize/tsan/suppressions_clang.cfg
+++ b/test/suite/transport_test/heap/sanitize/tsan/suppressions_clang.cfg
@@ -1,3 +1,8 @@
+# Current version assumption: clang-15/16/17.
+
+# Had some issues matching ^ and $ in this one; leaving them out; these are very unlikely to match something
+# unintentional.
+
 # This is for transport_test exercise mode heap sub-mode.
 
 # I have seen this warning exactly once as of this writing, with clang-15.  Upon careful analysis: it's got to be
@@ -63,4 +68,4 @@
 # fine even then (but that doesn't in itself prove there's no race of course).
 #
 # In the meantime suppress the issue at a few frames up from the reported problem.  Hopefully that takes care of it.
-race:^boost::asio::detail::epoll_reactor::~epoll_reactor$
+race:boost::asio::detail::epoll_reactor::~epoll_reactor
diff --git a/test/suite/transport_test/shm-c/sanitize/tsan/suppressions_clang.cfg b/test/suite/transport_test/shm-c/sanitize/tsan/suppressions_clang.cfg
index 5a0d7bb3e..b7a9d0541 100644
--- a/test/suite/transport_test/shm-c/sanitize/tsan/suppressions_clang.cfg
+++ b/test/suite/transport_test/shm-c/sanitize/tsan/suppressions_clang.cfg
@@ -1,3 +1,5 @@
+# Current version assumption: clang-15/16/17.
+
 # This is for transport_test exercise mode SHM-classic sub-mode.  Cf. exercise mode heap sub-mode: It passes cleanly
 # with ~no suppressions.  Yet SHM-classic sub-mode spams quite a few TSAN warnings.  Investigating them shows it is
 # *always* when reading or writing in SHM; and looking in more detail shows there is no real race; TSAN just cannot
diff --git a/test/suite/unit_test/sanitize/tsan/suppressions_clang.cfg b/test/suite/unit_test/sanitize/tsan/suppressions_clang.cfg
index d3bdf05fc..37b2b8b1a 100644
--- a/test/suite/unit_test/sanitize/tsan/suppressions_clang.cfg
+++ b/test/suite/unit_test/sanitize/tsan/suppressions_clang.cfg
@@ -1,9 +1,12 @@
 # Current version assumption: clang-15/16/17.
 
+# Had some issues matching ^ and $ in this one; leaving them out; these are very unlikely to match something
+# unintentional.
+
 # TODO: Explain these in detail.
-race:^ipc::shm::arena_lend::Borrower_shm_pool_collection::open_shm_pool$
-race:^ipc::session::shm::arena_lend::Shm_session_data::register_borrower_collection$
-race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::~Test_client$
-race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Object_event_listener::notify_object_received$
-race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Object_event_listener::~Object_event_listener$
+race:ipc::shm::arena_lend::Borrower_shm_pool_collection::open_shm_pool
+race:ipc::session::shm::arena_lend::Shm_session_data::register_borrower_collection
+race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::~Test_client
+race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Object_event_listener::notify_object_received
+race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Object_event_listener::~Object_event_listener
 # (End TODO.)
diff --git a/test/suite/unit_test/sanitize/tsan/suppressions_clang_15.cfg b/test/suite/unit_test/sanitize/tsan/suppressions_clang_15.cfg
index 544ec2730..f48067eaa 100644
--- a/test/suite/unit_test/sanitize/tsan/suppressions_clang_15.cfg
+++ b/test/suite/unit_test/sanitize/tsan/suppressions_clang_15.cfg
@@ -1,8 +1,13 @@
+# Current version assumption: clang-15/16/17.
+
+# Had some issues matching ^ and $ in this one; leaving them out; these are very unlikely to match something
+# unintentional.
+
 # TODO: Explain these in detail.
-race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::open_app_channel$
-race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client_manager::Client_data::~Client_data$
-race:^ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server_executor::many_objects_creator_functor$
-race:^ipc::test::Test_logger::Test_logger$
-race:^ipc::util::sync_io::Timer_event_emitter::Timer_event_emitter$
-race:^ipc::session::shm::arena_lend::Borrower_shm_pool_collection_repository::register_shm_pool$
+race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::open_app_channel
+race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client_manager::Client_data::~Client_data
+race:ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server_executor::many_objects_creator_functor
+race:ipc::test::Test_logger::Test_logger
+race:ipc::util::sync_io::Timer_event_emitter::Timer_event_emitter
+race:ipc::session::shm::arena_lend::Borrower_shm_pool_collection_repository::register_shm_pool
 # (End TODO.)
diff --git a/test/suite/unit_test/sanitize/tsan/suppressions_clang_16.cfg b/test/suite/unit_test/sanitize/tsan/suppressions_clang_16.cfg
index 36a879209..d286c0166 100644
--- a/test/suite/unit_test/sanitize/tsan/suppressions_clang_16.cfg
+++ b/test/suite/unit_test/sanitize/tsan/suppressions_clang_16.cfg
@@ -1,6 +1,11 @@
+# Current version assumption: clang-15/16/17.
+
+# Had some issues matching ^ and $ in this one; leaving them out; these are very unlikely to match something
+# unintentional.
+
 # TODO: Explain these in detail.
-race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::open_app_channel$
-race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client_manager::~Test_client_manager$
-race:^ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server::execute_allocation_performance_tests$
-race:^ipc::util::sync_io::Timer_event_emitter::Timer_event_emitter$
+race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client::open_app_channel
+race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Test_client_manager::~Test_client_manager
+race:ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server::execute_allocation_performance_tests
+race:ipc::util::sync_io::Timer_event_emitter::Timer_event_emitter
 # (End TODO.)
diff --git a/test/suite/unit_test/sanitize/tsan/suppressions_clang_17.cfg b/test/suite/unit_test/sanitize/tsan/suppressions_clang_17.cfg
index 9ec5d0c5f..2a4e5334d 100644
--- a/test/suite/unit_test/sanitize/tsan/suppressions_clang_17.cfg
+++ b/test/suite/unit_test/sanitize/tsan/suppressions_clang_17.cfg
@@ -1,5 +1,10 @@
+# Current version assumption: clang-15/16/17.
+
+# Had some issues matching ^ and $ in this one; leaving them out; these are very unlikely to match something
+# unintentional.
+
 # TODO: Explain these in detail.
-race:^ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Basic_event_listener::~Basic_event_listener$
-race:^ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server_executor::many_objects_creator_functor$
-race:^ipc::test::Test_logger::Test_logger$
+race:ipc::session::shm::arena_lend::jemalloc::test::(anonymous namespace)::Basic_event_listener::~Basic_event_listener
+race:ipc::session::shm::arena_lend::jemalloc::test::Test_shm_session_server_executor::many_objects_creator_functor
+race:ipc::test::Test_logger::Test_logger
 # (End TODO.)

From 0d6fa1576dab2b5d31c9b7077782ff2436743d66 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 17:16:52 -0800
Subject: [PATCH 11/23] Opportunistic manual updates.  Plus a minor test
 change.

---
 src/doc/manual/c-setup.dox.txt       | 12 +++++++++---
 test/suite/transport_test/ex_guy.hpp |  2 +-
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/doc/manual/c-setup.dox.txt b/src/doc/manual/c-setup.dox.txt
index d71aede79..a58dfe795 100644
--- a/src/doc/manual/c-setup.dox.txt
+++ b/src/doc/manual/c-setup.dox.txt
@@ -30,9 +30,13 @@ OS and build environment
 ------------------------
 @note In the short term (as of October 2023) this may become an open-source library with potentially wide distribution.  Some of the below items may change in that case; for example it may become a header-only library or have that mode, and it may support additional OS rather than Linux.  We would also include specific information on building it from source as befits a wide-release project.  Until then we leave out specific instructions on building the library itself as outside the scope of the present document; while listing the environmental requirements/recommendations as follows.  It is vaguely informational; until this is a wide-release library we stay away from rigorous build instructions here.  Even once it becomes a wide-release product, possibly such instructions shall live outside this manual.  Looking outside the src/ directory you'll certainly find the relevant build scripts which cover all that.
 
-This is a Linux library, as of this writing to be built in 64-bit mode (x86-64 a/k/a AMD64).  (Most code by far is not architecture-specific, but certain aspects of the optionally-used SHM-jemalloc component are.)  It is generally intended for use in a deployed server setting.  As of this writing it relies on some Linux-specific techniques such as /proc/...pid.../ and /dev/shm/ semantics.  In the future it is quite conceivable it could be extended to other OS and architectures -- possibly even Windows, but definitely MacOS/Darwin and FreeBSD -- but currently that is not a specific aim/priority of the project, as we concentrate on Linux.
+This is a Linux library (actually set of libraries, but in this Manual we treat Flow-IPC as a monolithic whole for simplicity).  As of this writing it is to be built in 64-bit mode (x86-64 a/k/a AMD64).  (Most code by far is not OS/architecture-specific, but at least certain aspects of the optionally-used SHM-jemalloc component are.)  It is generally intended for use in a deployed server setting.  As of this writing it relies on some Linux-specific techniques such as /proc/...pid.../ and /dev/shm/ semantics.  In the future it is quite conceivable it could be extended to other OS and architectures -- possibly even Windows, but definitely MacOS/Darwin and FreeBSD -- but currently that is not a specific aim/priority of the project, as we concentrate on Linux.
 
-It is a linked library that must be built in **C++17** compiler mode, as must any of its `#include`rs (translation units).  It has been specifically tested with gcc-8 and gcc-9 as of this writing.  common.hpp will `#error` out if an `#include`r is not being built with a supported compiler; and will `#warning` for compilers that would probably work but have not been tested, such as gcc below gcc-8.  (Support for clang is likely attainable and may arrive in the short term, if it has not already.  Again: look outside src/ for build scripts and related instructions if any.)
+It is a linked library (libraries) that must be built in **C++17** compiler mode, as must any of its `#include`rs (translation units).  It has been specifically tested (as of this writing) on a range of gcc and clang compilers/linkers.  We omit details in this text, since this is likely to evolve over time.  Generally such topics are well covered outside of src/ directories; start with the top-level `README.md` for an overview; it will point you to CMake scripts and so on -- if there is interest.
+
+Regarding the briefly-mentioned-above testing: As of this writing there is an automated CI/CD test suite which checks the various combinations of compiler and build-type (debug, release, various sanitizers, etc.) -- both building and functionality.  Again we omit details here; but as of this writing you can see the details at the official open-source project (GitHub organization "Flow-IPC," as I write this).  You'll likely find a few files like `.github/...`, `conanfile.py`, and sanitizer-specific `.cfg` files which control this stuff.  This is well outside our scope in this Manual, but we wanted you to be aware of such things.
+
+Regarding test code itself: We do not talk about it in this Manual or Reference (again: out of scope); but it is in the same repo (repos).  Some test code (of the unit-test variety) is in `test/` subdirs at various levels near production code; other test code is outside `src/` entirely -- whether the unit test driver program(s) or the various integration-tests.
 
 Flow-IPC strongly relies on a foundational library named Flow.  We expose certain aspects of Flow, most notably for logging (discussed below), through the API as well.  Informally and orthogonally, Flow is a nice tool we feel you're likely to find useful in any case at times.  (For capnp users: an analogy might be capnp's use of their in-house `kj` library both internally and at times exposed in capnp's own API.)  In any case you'll need to link and build with Flow to use Flow-IPC.
 
@@ -40,7 +44,9 @@ Flow has some dependencies, notably Boost, including certain linked (non-header-
 
 capnp (Cap'n Proto) is an important dependency; you must build and link with capnp to use Flow-IPC.  In particular that one, at the version we require, requires all `#include`rs to be built in C++17 mode.  Flow-IPC inherits this requirement from capnp (as well as Flow) and is not shy about using C++17 including in .hpp files.
 
-All in all, if you've got a reasonably modern Linux build and runtime environment, your application is built in at least C++17 mode, then there's nothing too exotic going on that would prevent the use of Flow-IPC (or Flow).  Boost and capnp do not introduce any array of exotic dependencies.
+Lastly, if one chooses to use the SHM-jemalloc provider of zero-copy transmission and/or direct SHM use, then the jemalloc library is a dependency as well.  Building jemalloc from source is a fairly simple task (a topic applicable if your consumer program does not already use jemalloc as a `malloc()` provider or other reasons).
+
+All in all, if you've got a reasonably modern Linux build and runtime environment, and your application is built in at least C++17 mode, then there's nothing too exotic going on that would prevent the use of Flow-IPC (or Flow).  Boost, capnp, and jemalloc do not introduce any array of exotic dependencies.
 
 Error reporting
 ---------------
diff --git a/test/suite/transport_test/ex_guy.hpp b/test/suite/transport_test/ex_guy.hpp
index f885c1d4b..0ed82fa8f 100644
--- a/test/suite/transport_test/ex_guy.hpp
+++ b/test/suite/transport_test/ex_guy.hpp
@@ -35,7 +35,7 @@
   ( \
     if (!(expr)) \
     { \
-      std::cerr << FLOW_UTIL_WHERE_AM_I() << "Condition failed; aborting.  The condition: [" << #expr << "].\n"; \
+      std::cerr << FLOW_UTIL_WHERE_AM_I() << ": Condition failed; aborting.  The condition: [" << #expr << "].\n"; \
       std::abort(); \
     } \
   )

From aa849e16e0f1863960e324869f95340ce3ecd208 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 17:21:03 -0800
Subject: [PATCH 12/23] Updating submodules.

---
 flow                     | 2 +-
 ipc_core                 | 2 +-
 ipc_session              | 2 +-
 ipc_shm                  | 2 +-
 ipc_shm_arena_lend       | 2 +-
 ipc_transport_structured | 2 +-
 6 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/flow b/flow
index 616b06a26..caf751b40 160000
--- a/flow
+++ b/flow
@@ -1 +1 @@
-Subproject commit 616b06a2663cb2838cff9875dea6d42ed3e505f3
+Subproject commit caf751b403e9adfccae35894965f5eae2cbc1492
diff --git a/ipc_core b/ipc_core
index 1ebe54b3b..f278e699e 160000
--- a/ipc_core
+++ b/ipc_core
@@ -1 +1 @@
-Subproject commit 1ebe54b3b551bb57c51768bd1d4ad51aeb2ddb97
+Subproject commit f278e699e8188251a1ec187e3285c2c9cbd4073b
diff --git a/ipc_session b/ipc_session
index 16fd0581e..4c5d8cc10 160000
--- a/ipc_session
+++ b/ipc_session
@@ -1 +1 @@
-Subproject commit 16fd0581e5012af015857dea0bf1af6cfb95c9e7
+Subproject commit 4c5d8cc10c205ebe1bfa4a41c32c4db174578ba9
diff --git a/ipc_shm b/ipc_shm
index 147e4b52e..9fd99e94a 160000
--- a/ipc_shm
+++ b/ipc_shm
@@ -1 +1 @@
-Subproject commit 147e4b52ea6e83d739f989289bde6a9f6d668a14
+Subproject commit 9fd99e94a657a834fc58a82b5116c319e33b3a1c
diff --git a/ipc_shm_arena_lend b/ipc_shm_arena_lend
index f21975e27..f6b89b851 160000
--- a/ipc_shm_arena_lend
+++ b/ipc_shm_arena_lend
@@ -1 +1 @@
-Subproject commit f21975e2720a6b5712d7a72b942d2f516b1f8e9b
+Subproject commit f6b89b851b66e7750966a4d7317280d003274e17
diff --git a/ipc_transport_structured b/ipc_transport_structured
index 78745321b..4fb1fa2dc 160000
--- a/ipc_transport_structured
+++ b/ipc_transport_structured
@@ -1 +1 @@
-Subproject commit 78745321b5216df8b2464714acb1f5affceb860e
+Subproject commit 4fb1fa2dca9e9969d3db9c47cea6714f4d9294a0

From 08cba0b488ff10520527660fd173cc0ea495f313 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:11:23 -0800
Subject: [PATCH 13/23] (debug)

---
 .github/workflows/main.yml | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index b6cc278d0..2cfea1223 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -41,8 +41,29 @@ jobs:
       with:
         submodules: true
 
+    # XXX
+    - name: Run integration test [transport_test - Exercise mode - SHM-jemalloc sub-mode]
+      id: transport_test_ex_shm_jxxx
+      if: |
+        (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
+                             &&
+                             (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan')))
+      run: |
+        echo 'Should skip later.'
+
+    # XXX
+    - name: Run integration test [transport_test - Exercise mode - SHM-jemalloc sub-mode]
+      id: transport_test_ex_shm_jxxx
+      if: |
+        !((!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
+                               &&
+                               (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan'))))
+      run: |
+        echo 'Should not skip later.'
+
     - name: Install Flow-IPC dependencies (like Graphviz) with apt-get
       run: |
+        false # XXX
         sudo apt-get install -y graphviz
 
     - name: Install the latest version of Conan which is less than 2

From 41970f0f293802f5ad76d5b3accc678185adacb0 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:12:46 -0800
Subject: [PATCH 14/23] (debug)

---
 .github/workflows/main.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 2cfea1223..77b8c3387 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -43,7 +43,7 @@ jobs:
 
     # XXX
     - name: Run integration test [transport_test - Exercise mode - SHM-jemalloc sub-mode]
-      id: transport_test_ex_shm_jxxx
+      id: transport_test_ex_shm_jxxx1
       if: |
         (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
                              &&
@@ -53,7 +53,7 @@ jobs:
 
     # XXX
     - name: Run integration test [transport_test - Exercise mode - SHM-jemalloc sub-mode]
-      id: transport_test_ex_shm_jxxx
+      id: transport_test_ex_shm_jxxx2
       if: |
         !((!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
                                &&

From 571223d4fc6e6b65d56a5990ea37101cec984a54 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:15:28 -0800
Subject: [PATCH 15/23] (debug)

---
 .github/workflows/main.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 77b8c3387..84504f212 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -42,7 +42,7 @@ jobs:
         submodules: true
 
     # XXX
-    - name: Run integration test [transport_test - Exercise mode - SHM-jemalloc sub-mode]
+    - name: Run 1 XXX
       id: transport_test_ex_shm_jxxx1
       if: |
         (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
@@ -52,7 +52,7 @@ jobs:
         echo 'Should skip later.'
 
     # XXX
-    - name: Run integration test [transport_test - Exercise mode - SHM-jemalloc sub-mode]
+    - name: Run 2 XXX
       id: transport_test_ex_shm_jxxx2
       if: |
         !((!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')

From 29d15662cec04857c7a91926a8c9fb508ae2c165 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:16:20 -0800
Subject: [PATCH 16/23] (debug)

---
 .github/workflows/main.yml | 40 +++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 84504f212..b81011fd8 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -41,26 +41,6 @@ jobs:
       with:
         submodules: true
 
-    # XXX
-    - name: Run 1 XXX
-      id: transport_test_ex_shm_jxxx1
-      if: |
-        (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
-                             &&
-                             (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan')))
-      run: |
-        echo 'Should skip later.'
-
-    # XXX
-    - name: Run 2 XXX
-      id: transport_test_ex_shm_jxxx2
-      if: |
-        !((!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
-                               &&
-                               (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan'))))
-      run: |
-        echo 'Should not skip later.'
-
     - name: Install Flow-IPC dependencies (like Graphviz) with apt-get
       run: |
         false # XXX
@@ -454,6 +434,26 @@ jobs:
         lsb_release -a
         sudo apt-get update
 
+    # XXX
+    - name: Run 1 XXX
+      id: transport_test_ex_shm_jxxx1
+      if: |
+        (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
+                             &&
+                             (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan')))
+      run: |
+        echo 'Should skip later.'
+
+    # XXX
+    - name: Run 2 XXX
+      id: transport_test_ex_shm_jxxx2
+      if: |
+        !((!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
+                               &&
+                               (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan'))))
+      run: |
+        echo 'Should not skip later.'
+
     - name: Checkout `ipc` repository and submodules (`flow`, `ipc_*`)
       uses: actions/checkout@v4
       with:

From ea1e62d251f688958431456976baa00b8e8c64bb Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:17:44 -0800
Subject: [PATCH 17/23] (debug)

---
 .github/workflows/main.yml | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index b81011fd8..6cf380746 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -438,8 +438,7 @@ jobs:
     - name: Run 1 XXX
       id: transport_test_ex_shm_jxxx1
       if: |
-        (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
-                             &&
+        (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17') &&
                              (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan')))
       run: |
         echo 'Should skip later.'
@@ -448,8 +447,7 @@ jobs:
     - name: Run 2 XXX
       id: transport_test_ex_shm_jxxx2
       if: |
-        !((!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
-                               &&
+        !((!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17') &&
                                (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan'))))
       run: |
         echo 'Should not skip later.'

From 870aaf8e32b0c7e72f9b170b32322541ccdfa3e1 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:18:24 -0800
Subject: [PATCH 18/23] (debug)

---
 .github/workflows/main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 6cf380746..b52e045b4 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -43,7 +43,6 @@ jobs:
 
     - name: Install Flow-IPC dependencies (like Graphviz) with apt-get
       run: |
-        false # XXX
         sudo apt-get install -y graphviz
 
     - name: Install the latest version of Conan which is less than 2
@@ -451,6 +450,7 @@ jobs:
                                (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan'))))
       run: |
         echo 'Should not skip later.'
+        false # XXX
 
     - name: Checkout `ipc` repository and submodules (`flow`, `ipc_*`)
       uses: actions/checkout@v4

From e0d00246e1267fbd2b7862dba2346abeab7d747d Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:20:51 -0800
Subject: [PATCH 19/23] (debug)

---
 .github/workflows/main.yml | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index b52e045b4..a87abb567 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -440,7 +440,8 @@ jobs:
         (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17') &&
                              (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan')))
       run: |
-        echo 'Should skip later.'
+        echo 'Should skip later. [${{ matrix.compiler.id }}][${{ matrix.build-test-cfg.sanitizer-name }}]'
+        false # XXX
 
     # XXX
     - name: Run 2 XXX
@@ -449,7 +450,7 @@ jobs:
         !((!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17') &&
                                (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan'))))
       run: |
-        echo 'Should not skip later.'
+        echo 'Should not skip later. [${{ matrix.compiler.id }}][${{ matrix.build-test-cfg.sanitizer-name }}]'
         false # XXX
 
     - name: Checkout `ipc` repository and submodules (`flow`, `ipc_*`)

From 7d3028a0b5239498888443f475c4055ded4f3a65 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:25:20 -0800
Subject: [PATCH 20/23] (debug)

---
 .github/workflows/main.yml | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index a87abb567..bbb3e3e75 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -43,6 +43,7 @@ jobs:
 
     - name: Install Flow-IPC dependencies (like Graphviz) with apt-get
       run: |
+        false # XXX
         sudo apt-get install -y graphviz
 
     - name: Install the latest version of Conan which is less than 2
@@ -437,21 +438,19 @@ jobs:
     - name: Run 1 XXX
       id: transport_test_ex_shm_jxxx1
       if: |
-        (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17') &&
-                             (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan')))
+        (!cancelled()) && ((${{ matrix.compiler.id }} != 'clang-17') ||
+                           (${{ matrix.build-test-cfg.sanitizer-name }} != 'tsan'))
       run: |
         echo 'Should skip later. [${{ matrix.compiler.id }}][${{ matrix.build-test-cfg.sanitizer-name }}]'
-        false # XXX
 
     # XXX
     - name: Run 2 XXX
       id: transport_test_ex_shm_jxxx2
       if: |
-        !((!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17') &&
-                               (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan'))))
+        !((!cancelled()) && ((${{ matrix.compiler.id }} != 'clang-17') ||
+                             (${{ matrix.build-test-cfg.sanitizer-name }} != 'tsan')))
       run: |
         echo 'Should not skip later. [${{ matrix.compiler.id }}][${{ matrix.build-test-cfg.sanitizer-name }}]'
-        false # XXX
 
     - name: Checkout `ipc` repository and submodules (`flow`, `ipc_*`)
       uses: actions/checkout@v4
@@ -462,6 +461,7 @@ jobs:
       if: |
         matrix.compiler.install && (matrix.compiler.name == 'clang')
       run: |
+        false # XXX
         wget https://apt.llvm.org/llvm.sh
         chmod u+x llvm.sh
         sudo ./llvm.sh ${{ matrix.compiler.version }}

From c8dbd2bf54ce2172606503264d7fb6d5fdd850df Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:29:14 -0800
Subject: [PATCH 21/23] (debug)

---
 .github/workflows/main.yml | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index bbb3e3e75..a8f025f1b 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -438,8 +438,7 @@ jobs:
     - name: Run 1 XXX
       id: transport_test_ex_shm_jxxx1
       if: |
-        (!cancelled()) && ((${{ matrix.compiler.id }} != 'clang-17') ||
-                           (${{ matrix.build-test-cfg.sanitizer-name }} != 'tsan'))
+        (${{ matrix.compiler.id }} != 'clang-17') || (${{ matrix.build-test-cfg.sanitizer-name }} != 'tsan'))
       run: |
         echo 'Should skip later. [${{ matrix.compiler.id }}][${{ matrix.build-test-cfg.sanitizer-name }}]'
 
@@ -447,8 +446,7 @@ jobs:
     - name: Run 2 XXX
       id: transport_test_ex_shm_jxxx2
       if: |
-        !((!cancelled()) && ((${{ matrix.compiler.id }} != 'clang-17') ||
-                             (${{ matrix.build-test-cfg.sanitizer-name }} != 'tsan')))
+        (${{ matrix.compiler.id }} == 'clang-17') && (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan'))
       run: |
         echo 'Should not skip later. [${{ matrix.compiler.id }}][${{ matrix.build-test-cfg.sanitizer-name }}]'
 

From 3e889f5f92bff5e1557f54b6cc8af62c1b049319 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:35:38 -0800
Subject: [PATCH 22/23] (debug)

---
 .github/workflows/main.yml | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index a8f025f1b..50d8e67aa 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -154,7 +154,7 @@ jobs:
             # In any case Debug, at the CMake script (in meta-project ./, and in flow/, ipc_*/) level,
             # means LTO will be ignored (only *Rel* build-types enable LTO, if so instructed).
             # Still keeping this here to make that clear to the reader/maintainer.  Could remove it though.
-            no-lto: true
+            no-lto: True
           - id: release
             conan-profile-build-type: Release
             conan-profile-jemalloc-build-type: Release
@@ -167,7 +167,7 @@ jobs:
             # we can use a test of non-LTO building.
             # TODO: Perhaps this should be a separate matrix dimension (LTO on, LTO off).  Number of configs will
             # jump up, but it is more methodical and nice.
-            no-lto: true
+            no-lto: True
           - id: minsizerel
             conan-profile-build-type: MinSizeRel
             conan-profile-jemalloc-build-type: Release
@@ -194,7 +194,7 @@ jobs:
             # At least ASAN with clang + LTO => cryptic link error.
             # Regardless regular RelWithDebInfo already has no-lto=true; so we would follow suit.  Just be aware
             # that changing it to false for whatever reason => ASAN probably breaks.
-            no-lto: true
+            no-lto: True
           - id: relwithdebinfo-ubsan
             conan-profile-build-type: RelWithDebInfo
             conan-profile-jemalloc-build-type: Release
@@ -215,7 +215,7 @@ jobs:
             sanitizer-name: ubsan
             # While UBSAN might work with LTO, I do not want the aggravation/entropy.  Turn it off.
             # Plus inheriting from regular RelWithDebInfo anyway.
-            no-lto: true
+            no-lto: True
           - id: relwithdebinfo-tsan
             conan-profile-build-type: RelWithDebInfo
             conan-profile-jemalloc-build-type: Release
@@ -254,7 +254,7 @@ jobs:
             # Also, for some clangs, there are TSAN WARNINGs at times about too-small symbolizer buffer or something;
             # throwing LTO into the mix seems like unnecessary entropy.
             # Plus inheriting from regular RelWithDebInfo anyway.
-            no-lto: true
+            no-lto: True
           - id: relwithdebinfo-msan
             conan-profile-build-type: RelWithDebInfo
             conan-profile-jemalloc-build-type: Release
@@ -275,7 +275,7 @@ jobs:
             sanitizer-name: msan
             # While MSAN might work with LTO, I do not want the aggravation/entropy.  Turn it off.
             # Plus inheriting from regular RelWithDebInfo anyway.
-            no-lto: true
+            no-lto: True
 
         # We concentrate on clang sanitizers; they are newer/nicer; also MSAN is clang-only.  So gcc ones excluded.
         # Attention!  Excluding some sanitizer job(s) (with these reasons):
@@ -438,7 +438,8 @@ jobs:
     - name: Run 1 XXX
       id: transport_test_ex_shm_jxxx1
       if: |
-        (${{ matrix.compiler.id }} != 'clang-17') || (${{ matrix.build-test-cfg.sanitizer-name }} != 'tsan'))
+        (!cancelled()) && ((matrix.compiler.id != 'clang-17') ||
+                           (matrix.build-test-cfg.sanitizer-name != 'tsan'))
       run: |
         echo 'Should skip later. [${{ matrix.compiler.id }}][${{ matrix.build-test-cfg.sanitizer-name }}]'
 
@@ -446,7 +447,8 @@ jobs:
     - name: Run 2 XXX
       id: transport_test_ex_shm_jxxx2
       if: |
-        (${{ matrix.compiler.id }} == 'clang-17') && (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan'))
+        !((!cancelled()) && ((matrix.compiler.id != 'clang-17') ||
+                             (matrix.build-test-cfg.sanitizer-name != 'tsan')))
       run: |
         echo 'Should not skip later. [${{ matrix.compiler.id }}][${{ matrix.build-test-cfg.sanitizer-name }}]'
 
@@ -555,7 +557,7 @@ jobs:
         ipc:doc = False
         ipc:build = True
         EOF
-        if [ "${{ matrix.build-test-cfg.no-lto }}" != '' ] && [ "${{ matrix.build-test-cfg.no-lto }}" != 'false' ]; then
+        if [ "${{ matrix.build-test-cfg.no-lto }}" != '' ] && [ "${{ matrix.build-test-cfg.no-lto }}" != 'False' ]; then
           echo 'ipc:build_no_lto = True' >> conan_profile
         fi
         if [ "${{ matrix.build-test-cfg.build-type-cflags-override }}" != '' ]; then

From 3cb376d87d5de4176fbafea193aab852bc5ba2d9 Mon Sep 17 00:00:00 2001
From: Yuri Goldfeld <yuri.goldfeld@yahoo.com>
Date: Wed, 20 Dec 2023 20:37:58 -0800
Subject: [PATCH 23/23] Fixing an absolutely moronic error on my part.  WTF!  I
 have been messing with this pipeline for too ling.

---
 .github/workflows/main.yml | 25 ++-----------------------
 1 file changed, 2 insertions(+), 23 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 50d8e67aa..f250a6600 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -43,7 +43,6 @@ jobs:
 
     - name: Install Flow-IPC dependencies (like Graphviz) with apt-get
       run: |
-        false # XXX
         sudo apt-get install -y graphviz
 
     - name: Install the latest version of Conan which is less than 2
@@ -434,24 +433,6 @@ jobs:
         lsb_release -a
         sudo apt-get update
 
-    # XXX
-    - name: Run 1 XXX
-      id: transport_test_ex_shm_jxxx1
-      if: |
-        (!cancelled()) && ((matrix.compiler.id != 'clang-17') ||
-                           (matrix.build-test-cfg.sanitizer-name != 'tsan'))
-      run: |
-        echo 'Should skip later. [${{ matrix.compiler.id }}][${{ matrix.build-test-cfg.sanitizer-name }}]'
-
-    # XXX
-    - name: Run 2 XXX
-      id: transport_test_ex_shm_jxxx2
-      if: |
-        !((!cancelled()) && ((matrix.compiler.id != 'clang-17') ||
-                             (matrix.build-test-cfg.sanitizer-name != 'tsan')))
-      run: |
-        echo 'Should not skip later. [${{ matrix.compiler.id }}][${{ matrix.build-test-cfg.sanitizer-name }}]'
-
     - name: Checkout `ipc` repository and submodules (`flow`, `ipc_*`)
       uses: actions/checkout@v4
       with:
@@ -461,7 +442,6 @@ jobs:
       if: |
         matrix.compiler.install && (matrix.compiler.name == 'clang')
       run: |
-        false # XXX
         wget https://apt.llvm.org/llvm.sh
         chmod u+x llvm.sh
         sudo ./llvm.sh ${{ matrix.compiler.version }}
@@ -930,9 +910,8 @@ jobs:
     - name: Run integration test [transport_test - Exercise mode - SHM-jemalloc sub-mode]
       id: transport_test_ex_shm_j
       if: |
-        (!cancelled()) && (!((${{ matrix.compiler.id }} == 'clang-17')
-                             &&
-                             (${{ matrix.build-test-cfg.sanitizer-name }} == 'tsan')))
+        (!cancelled()) && ((matrix.compiler.id != 'clang-17') ||
+                           (matrix.build-test-cfg.sanitizer-name != 'tsan'))
       run: |
         /usr/bin/bash -e \
           ${{ env.install-dir }}/bin/run_transport_test_ex.sh \