From 3905171f1ea778c60c74dd4b0318b894eda94d7f Mon Sep 17 00:00:00 2001 From: "Gregory P. Smith" Date: Sat, 29 Sep 2012 11:40:38 -0700 Subject: [PATCH] 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. --- Lib/subprocess.py | 9 ++++++++- Lib/test/subprocessdata/sigchild_ignore.py | 11 ++++++++++- Misc/NEWS | 4 ++++ 3 files changed, 22 insertions(+), 2 deletions(-) diff --git a/Lib/subprocess.py b/Lib/subprocess.py index 106af8b2619..93262df7ab4 100644 --- a/Lib/subprocess.py +++ b/Lib/subprocess.py @@ -1400,9 +1400,16 @@ class Popen(object): 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 6072aece28a..86320fb35e7 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') diff --git a/Misc/NEWS b/Misc/NEWS index cb1df24f5a5..7347f502e41 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -123,6 +123,10 @@ Core and Builtins Library ------- +- 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. + - Issue #12376: Pass on parameters in TextTestResult.__init__ super call - Issue #15222: Insert blank line after each message in mbox mailboxes