From 048f4880a1d94f3e96af56e74473d7016ea044ea Mon Sep 17 00:00:00 2001
From: Marc Herbert <marc.herbert@intel.com>
Date: Thu, 3 Dec 2020 22:09:28 -0800
Subject: [PATCH] exit handler: don't use a subshell to list children still
 running

Use a new children_left.txt log file instead.

Using a subshell forced us to filter it out with grep -v $SCRIPT_NAME
which is more complicated, incompatible with exec wrappers like
multiple-pipeline-capture/playback.sh and incompatible with running
concurrent instances.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>
---
 case-lib/hijack.sh | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/case-lib/hijack.sh b/case-lib/hijack.sh
index bd5e12d2..59b455fe 100644
--- a/case-lib/hijack.sh
+++ b/case-lib/hijack.sh
@@ -148,13 +148,10 @@ function func_exit_handler()
 
     # get ps command result as list
     local -a cmd_lst
-    # $$ as current script pid
-    # NOTICE: already test with $BASHPID:
-    # it can output the same result of $$
-    # but the result could not be stored in the array
-    readarray -t cmd_lst < <(pgrep -P $$ -a|grep -v "$SCRIPT_NAME")
+    # can't run pgrep in any subshell because the latter would pollute the list
+    if pgrep -P $$ -a > "$LOG_ROOT/children_left.txt"; then
+        readarray -t cmd_lst < "$LOG_ROOT/children_left.txt"
     # now force kill target process which maybe block the script quit
-    if [ ${#cmd_lst[@]} -gt 0 ]; then
         local line
         dlogw "Process(es) started by $SCRIPT_NAME are still active, killing these process(es):"
         for line in "${cmd_lst[@]}"
@@ -163,6 +160,8 @@ function func_exit_handler()
             dlogw "Kill cmd:'${line#* }' by kill -9"
             kill -9 "${line%% *}"
         done
+    else
+        rm  "$LOG_ROOT/children_left.txt"
     fi
 
     # check if function already defined.