Issue #1731717: Fixed the problem where subprocess.wait() could cause an
OSError exception when The OS had been told to ignore SIGCLD in our process
or otherwise not wait for exiting child processes.
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index ac46ce8..452611c 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1295,7 +1295,11 @@
os.close(errpipe_read)
if data:
- _eintr_retry_call(os.waitpid, self.pid, 0)
+ try:
+ _eintr_retry_call(os.waitpid, self.pid, 0)
+ except OSError as e:
+ if e.errno != errno.ECHILD:
+ raise
try:
exception_name, hex_errno, err_msg = data.split(b':', 2)
except ValueError:
@@ -1358,7 +1362,15 @@
"""Wait for child process to terminate. Returns returncode
attribute."""
if self.returncode is None:
- pid, sts = _eintr_retry_call(os.waitpid, self.pid, 0)
+ try:
+ pid, sts = _eintr_retry_call(os.waitpid, self.pid, 0)
+ except OSError as e:
+ if e.errno != errno.ECHILD:
+ raise
+ # 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.
+ sts = 0
self._handle_exitstatus(sts)
return self.returncode
diff --git a/Lib/test/subprocessdata/sigchild_ignore.py b/Lib/test/subprocessdata/sigchild_ignore.py
new file mode 100644
index 0000000..1d03303
--- /dev/null
+++ b/Lib/test/subprocessdata/sigchild_ignore.py
@@ -0,0 +1,6 @@
+import signal, subprocess, sys
+# 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.SIGCLD, signal.SIG_IGN)
+subprocess.Popen([sys.executable, '-c', 'print("albatross")']).wait()
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 0804a13..1e97bac 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -1073,6 +1073,16 @@
close_fds=False, pass_fds=(fd, )))
self.assertIn('overriding close_fds', str(context.warning))
+ def test_wait_when_sigchild_ignored(self):
+ # NOTE: sigchild_ignore.py may not be an effective test on all OSes.
+ sigchild_ignore = support.findfile("sigchild_ignore.py",
+ subdir="subprocessdata")
+ p = subprocess.Popen([sys.executable, sigchild_ignore],
+ stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+ stdout, stderr = p.communicate()
+ self.assertEqual(0, p.returncode, "sigchild_ignore.py exited"
+ " non-zero with this error:\n%s" % stderr)
+
@unittest.skipUnless(mswindows, "Windows specific tests")
class Win32ProcessTestCase(BaseTestCase):