Red Hat Bugzilla – Bug 667431
Python Popen.communicate is unable to collect stderr, stdout and returncode for a short lived processes
Last modified: 2016-05-31 21:40:58 EDT
Created attachment 471885 [details] test_shortprocess.py Description of problem: Using Popen.communicate over a short-lived process results in a broken pipe exception (errno 32) which will prevent to collect the stderr, stdout and returncode of the dead process. Version-Release number of selected component (if applicable): # rpm -qf /usr/lib64/python2.6/subprocess.py python-2.6.5-3.el6.x86_64 How reproducible: $ python test_shortprocess.py Actual results: None Traceback (most recent call last): File "test_shortprocess.py", line 7, in <module> out, err = p.communicate(2**20 * '\0') File "/usr/lib64/python2.7/subprocess.py", line 740, in communicate return self._communicate(input) File "/usr/lib64/python2.7/subprocess.py", line 1256, in _communicate stdout, stderr = self._communicate_with_poll(input) File "/usr/lib64/python2.7/subprocess.py", line 1319, in _communicate_with_poll input_offset += os.write(fd, chunk) OSError: [Errno 32] Broken pipe Expected results: $ python test_process-fix.py dd: unrecognized operand `option=crash' Try `dd --help' for more information. 1
Created attachment 471886 [details] subprocess-sigpipe-el6.patch Proposed patch for el6.
Created attachment 471887 [details] subprocess-sigpipe-fc14.patch Proposed patch for fc14.
Thanks for filing this bug. I've filed it within the upstream python tracker as: http://bugs.python.org/issue10963 The patch I've attached there slightly reworks the fix, and adds a unit test. However, I'm not fully convinced that this is the correct approach, in that the change could mask stdin under-reads from poorly-written subprocesses that exit with failures but don't return with a non-zero exit code (alas, too many programs exit with 0 even when exiting with an error).
Development Management has reviewed and declined this request. You may appeal this decision by reopening this request.
Created attachment 490627 [details] Backport of the upstream patch The attached patch is a backport of the patch applied upstream to 2.7 to the somewhat modified 2.6.6 currently in RHEL 6.1 The upstream patch contained two new test cases; I've added some additional cases over and above those ones. All of test/test_subprocess.py passes on my test build (x86_64; python-2.6.6-17 + this new patch) I've also tested the patched version using attachment 471885 [details] (from comment #0), and it fixes the reported traceback, giving the expected results.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHBA-2011-1564.html