[libc] Resolve race condition in sub-process test runner.
authorPaula Toth <paulatoth@google.com>
Tue, 17 Mar 2020 19:59:21 +0000 (12:59 -0700)
committerPaula Toth <paulatoth@google.com>
Tue, 17 Mar 2020 20:00:00 +0000 (13:00 -0700)
commit17566573b2997e468cb4190c6853b1ebea125962
tree7b4413147928a8eb9b39397019c3ea53b3655fbf
parent2bd1ca28c1f1ea4b865790a6299f71496652fd2d
[libc] Resolve race condition in sub-process test runner.

Summary:
There seems to be a race condition between the pipe closing and the child process death. Likely these two events are not atomic on some versions of linux.

With the removal of `WNOHANG` we eliminate the race condition, however if the child closes the pipe intentionally then it could result in the test runner hanging. I find this situation less likely, where as I experience failures locally with this race condition rather consistently.

Reviewers: sivachandra, abrachet

Reviewed By: sivachandra, abrachet

Subscribers: MaskRay, jfb, tschuett, libc-commits

Tags: #libc-project

Differential Revision: https://reviews.llvm.org/D76267
libc/utils/testutils/ExecuteFunctionUnix.cpp