Fixes issue #15756: subprocess.poll() now properly handles errno.ECHILD
to return a returncode of 0 when the child has already exited or cannot
be waited on.
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 106af8b..93262df 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1400,9 +1400,16 @@
pid, sts = _waitpid(self.pid, _WNOHANG)
if pid == self.pid:
self._handle_exitstatus(sts)
- except _os_error:
+ except _os_error as e:
if _deadstate is not None:
self.returncode = _deadstate
+ elif e.errno == errno.ECHILD:
+ # 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.
+ # http://bugs.python.org/issue15756
+ self.returncode = 0
return self.returncode
diff --git a/Lib/test/subprocessdata/sigchild_ignore.py b/Lib/test/subprocessdata/sigchild_ignore.py
index 6072aec..86320fb 100644
--- a/Lib/test/subprocessdata/sigchild_ignore.py
+++ b/Lib/test/subprocessdata/sigchild_ignore.py
@@ -1,6 +1,15 @@
-import signal, subprocess, sys
+import signal, subprocess, sys, time
# On Linux this causes os.waitpid to fail with OSError as the OS has already
# reaped our child process. The wait() passing the OSError on to the caller
# and causing us to exit with an error is what we are testing against.
signal.signal(signal.SIGCHLD, signal.SIG_IGN)
subprocess.Popen([sys.executable, '-c', 'print("albatross")']).wait()
+# Also ensure poll() handles an errno.ECHILD appropriately.
+p = subprocess.Popen([sys.executable, '-c', 'print("albatross")'])
+num_polls = 0
+while p.poll() is None:
+ # Waiting for the process to finish.
+ time.sleep(0.01) # Avoid being a CPU busy loop.
+ num_polls += 1
+ if num_polls > 3000:
+ raise RuntimeError('poll should have returned 0 within 30 seconds')