[New-bugs-announce] [issue31173] test_subprocess: test_child_terminated_in_stopped_state() leaks a zombie process

[STINNER Victor]

New submission from STINNER Victor:

The test_child_terminated_in_stopped_state() test creates a child process which calls ptrace(PTRACE_ME, 0, 0) and then crashs using SIGSEGV. The problem is that even if we read the exit status using os.waitpid() through subprocess, the process remains alive in the "t (tracing stop)" state.

I would prefer to not use ptrace() is an unit test since this API is very low-level and it's hard to use it correctly.

I suggest to either remove the functional test, or to rewrite it as an unit test using mocks to test bpo-29335 without ptrace().

haypo at selma$ ./python -m test -m test_child_terminated_in_stopped_state -F test_subprocess
Run tests sequentially
0:00:00 load avg: 0.95 [  1] test_subprocess
0:00:00 load avg: 0.95 [  2] test_subprocess
0:00:01 load avg: 0.96 [  3] test_subprocess
0:00:01 load avg: 0.96 [  4] test_subprocess
0:00:02 load avg: 0.96 [  5] test_subprocess
0:00:03 load avg: 0.96 [  6] test_subprocess
0:00:03 load avg: 0.96 [  7] test_subprocess
0:00:04 load avg: 0.96 [  8] test_subprocess
0:00:05 load avg: 0.96 [  9] test_subprocess
0:00:05 load avg: 0.96 [ 10] test_subprocess
^Z
[1]+  Stoppé                 ./python -m test -m test_child_terminated_in_stopped_state -F test_subprocess

haypo at selma$ ps
  PID TTY          TIME CMD
30359 pts/0    00:00:00 bash
31882 pts/0    00:00:00 python
31885 pts/0    00:00:00 python
31888 pts/0    00:00:00 python
31892 pts/0    00:00:00 python
31895 pts/0    00:00:00 python
31898 pts/0    00:00:00 python
31901 pts/0    00:00:00 python
31904 pts/0    00:00:00 python
31907 pts/0    00:00:00 python
31910 pts/0    00:00:00 python
31912 pts/0    00:00:00 python
31920 pts/0    00:00:00 ps

haypo at selma$ grep Stat /proc/31885/status
State:	t (tracing stop)

----------
messages: 300066
nosy: haypo
priority: normal
severity: normal
status: open
title: test_subprocess: test_child_terminated_in_stopped_state() leaks a zombie process

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue31173>
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