Fixes issue #14396: Handle the odd rare case of waitpid returning 0 when

not expected in subprocess.Popen.wait().

2 files changed, 9 insertions, 2 deletions

diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 83c79ef..35a98c8 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1428,7 +1428,7 @@ class Popen(object):
         def wait(self):
             """Wait for child process to terminate.  Returns returncode
             attribute."""
-            if self.returncode is None:
+            while self.returncode is None:
                 try:
                     pid, sts = _eintr_retry_call(os.waitpid, self.pid, 0)
                 except OSError as e:
@@ -1437,8 +1437,12 @@ class Popen(object):
                     # This happens if SIGCLD is set to be ignored or waiting
                     # for child processes has otherwise been disabled for our
                     # process.  This child is dead, we can't get the status.
+                    pid = self.pid
                     sts = 0
-                self._handle_exitstatus(sts)
+                # Check the pid and loop as waitpid has been known to return
+                # 0 even without WNOHANG in odd situations.  issue14396.
+                if pid == self.pid:
+                    self._handle_exitstatus(sts)
             return self.returncode
 
 
diff --git a/Misc/NEWS b/Misc/NEWS
index 6a97cbc..a4f765a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@ What's New in Python 3.2.4
 Core and Builtins
 -----------------
 
+- Issue #14396: Handle the odd rare case of waitpid returning 0 when not
+  expected in subprocess.Popen.wait().
+
 - Issue #9535: Fix pending signals that have been received but not yet
   handled by Python to not persist after os.fork() in the child process.