Enhance support.reap_children() (#3036)

* reap_children() now sets environment_altered to True to detect bugs
  using python3 -m test --fail-env-changed
* Replace bare "except:" with "except OSError:" in reap_children()
* Write an unit test for reap_children() using a timeout of 60
  seconds

1 files changed, 21 insertions, 12 deletions

diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index 7a4671c..0235498 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -2073,26 +2073,35 @@ def reap_threads(func):
             threading_cleanup(*key)
     return decorator
 
+
 def reap_children():
     """Use this function at the end of test_main() whenever sub-processes
     are started.  This will help ensure that no extra children (zombies)
     stick around to hog resources and create problems when looking
     for refleaks.
     """
+    global environment_altered
+
+    # Need os.waitpid(-1, os.WNOHANG): Windows is not supported
+    if not (hasattr(os, 'waitpid') and hasattr(os, 'WNOHANG')):
+        return
+
     # Reap all our dead child processes so we don't leave zombies around.
     # These hog resources and might be causing some of the buildbots to die.
-    if hasattr(os, 'waitpid'):
-        any_process = -1
-        while True:
-            try:
-                # This will raise an exception on Windows.  That's ok.
-                pid, status = os.waitpid(any_process, os.WNOHANG)
-                if pid == 0:
-                    break
-                print("Warning -- reap_children() reaped child process %s"
-                      % pid, file=sys.stderr)
-            except:
-                break
+    while True:
+        try:
+            # Read the exit status of any child process which already completed
+            pid, status = os.waitpid(-1, os.WNOHANG)
+        except OSError:
+            break
+
+        if pid == 0:
+            break
+
+        print("Warning -- reap_children() reaped child process %s"
+              % pid, file=sys.stderr)
+        environment_altered = True
+
 
 @contextlib.contextmanager
 def start_threads(threads, unlock=None):