8000 bpo-6721: Sanitize logging locks while forking by gpshead · Pull Request #4071 · python/cpython · GitHub
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bpo-6721: Sanitize logging locks while forking #4071

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Merged
merged 7 commits into from
Sep 14, 2018
Merged

bpo-6721: Sanitize logging locks while forking #4071

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64a53be
[bpo-6721] Sanitize logging locks while forking.
gpshead Oct 21, 2017
a0c2cfb
Use the WeakSet approach per code review.
gpshead Sep 12, 2018
1d5bbcb
blurb
gpshead Sep 13, 2018
6be017a
Make the logic conditional on register_at_fork.
gpshead Sep 13, 2018
ebb4b74
Add a unittest!
gpshead Sep 13, 2018
5d5426f
Actually use the registration fn...
gpshead Sep 13, 2018
1066bb1
Fix the test to actually work.
gpshead Sep 13, 2018
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Add a unittest!
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@gpshead
gpshead committed Sep 13, 2018
commit ebb4b743826263f3400c66fa2c55fdef5968264d
39 changes: 39 additions & 0 deletions Lib/test/test_logging.py
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@
import queue
import random
import re
import signal
import socket
import struct
import sys
Expand Down Expand Up @@ -666,6 +667,44 @@ def remove_loop(fname, tries):
if os.path.exists(fn):
os.unlink(fn)

# The implementation relies on os.register_at_fork existing, but we test
# based on os.fork existing because that is what users and this test use.
# This helps ensure that when fork exists (the important concept) that the
# register_at_fork mechanism is also present and used.
@unittest.skipIf(not hasattr(os, 'fork'), 'Test requires os.fork().')
def test_post_fork_child_no_deadlock(self):
"""Ensure forked child logging locks are not held; bpo-6721."""
refed_h = logging.Handler()
refed_h.name = 'because we need at least one for this test'
logging._acquireLock()
try:
self.assertGreater(len(logging._handlers), 0)
the_handler = next(iter(logging._handlers.values()))
the_handler.acquire()
try:
pid = os.fork()
if pid == 0: # Child.
logging.error(r'Child process did not deadlock. \o/')
os._exit(0)
else: # Parent.
start_time = time.monotonic()
while True:
waited_pid, status = os.waitpid(pid, os.WNOHANG)
if waited_pid == pid:
break # child process exited.
if time.monotonic() - start_time > 20:
break # so long? implies child deadlock.
time.sleep(0.05)
if waited_pid != pid:
os.kill(pid, signal.SIGKILL)
waited_pid, status = os.waitpid(pid, 0)
self.fail("child process deadlocked.")
self.assertEqual(status, 0, msg="child process error")
finally:
the_handler.release()
finally:
logging._releaseLock()


class BadStream(object):
def write(self, data):
Expand Down
0