From 511fbb5c73acf1177fb29cabe8d92ed11b58ed00 Mon Sep 17 00:00:00 2001
From: Yury Selivanov <yury@magic.io>
Date: Mon, 7 Nov 2016 14:51:00 -0500
Subject: [PATCH 1/2] Fix remove_signal_handler to not to crush after
 PyOS_FiniInterrupts

---
 asyncio/unix_events.py | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/asyncio/unix_events.py b/asyncio/unix_events.py
index 65b61db6..7eb0241f 100644
--- a/asyncio/unix_events.py
+++ b/asyncio/unix_events.py
@@ -1,5 +1,6 @@
 """Selector event loop for Unix with signal handling."""
 
+import atexit
 import errno
 import os
 import signal
@@ -9,6 +10,7 @@
 import sys
 import threading
 import warnings
+import weakref
 
 
 from . import base_events
@@ -39,6 +41,12 @@ def _sighandler_noop(signum, frame):
     pass
 
 
+def _loop_atexit_callback(loop_ref):
+    loop = loop_ref()
+    if loop is not None:
+        loop._interpreter_shutting_down = True
+
+
 class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
     """Unix event loop.
 
@@ -47,6 +55,15 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
 
     def __init__(self, selector=None):
         super().__init__(selector)
+
+        # atexit callbacks are fired before PyOS_FiniInterrupts, which
+        # allows us to workaround bugs in remove_signal_handler.
+        atexit.register(_loop_atexit_callback, weakref.ref(self))
+        # When _interpreter_shutting_down is True, PyOS_FiniInterrupts
+        # has already been called and signalmodule's internal state was
+        # cleaned up.
+        self._interpreter_shutting_down = False
+
         self._signal_handlers = {}
 
     def _socketpair(self):
@@ -124,6 +141,11 @@ def remove_signal_handler(self, sig):
 
         Return True if a signal handler was removed, False if not.
         """
+        if self._interpreter_shutting_down:
+            # The interpreter is being shutdown.  `PyOS_FiniInterrupts`
+            # was already called and it has restored all signals already.
+            return
+
         self._check_signal(sig)
         try:
             del self._signal_handlers[sig]

From 92f36ae82295fbf8d182d1e6f1338a51afd7f76b Mon Sep 17 00:00:00 2001
From: Yury Selivanov <yury@magic.io>
Date: Mon, 7 Nov 2016 16:29:04 -0500
Subject: [PATCH 2/2] Issue a warning in debug mode; return False when
 interpreter is finalizing

---
 asyncio/unix_events.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/asyncio/unix_events.py b/asyncio/unix_events.py
index 7eb0241f..658e7e93 100644
--- a/asyncio/unix_events.py
+++ b/asyncio/unix_events.py
@@ -144,7 +144,11 @@ def remove_signal_handler(self, sig):
         if self._interpreter_shutting_down:
             # The interpreter is being shutdown.  `PyOS_FiniInterrupts`
             # was already called and it has restored all signals already.
-            return
+            if self._debug:
+                warnings.warn(
+                    "the loop was not closed properly; call loop.close()",
+                    ResourceWarning)
+            return False
 
         self._check_signal(sig)
         try: