cagney <andrew.cag...@gmail.com> added the comment:
On Fri, 5 Apr 2019 at 05:02, Gregory P. Smith <rep...@bugs.python.org> wrote:
>
>
> Gregory P. Smith <g...@krypto.org> added the comment:
>
> A stdlib alternative to this whole mess would be to avoid acquiring the
> logging locks before fork() as we currently do and just blindly re-initialize
> all of them afterwards under the assumption that they "can't" be protecting
> anything in a newly forked child process. Handlers that need specific
> resource synchronization around fork would then be required to deal with
> their own os.register_at_fork() calls. (ex: to avoid multiple processes
> writing to the same file or fd at once)
FYI, below is a simpler, but related, test.
_at_fork_acquire_release_weakset doesn't seem to be locked:
Ignoring exception from logging atfork <Handler (NOTSET)> release
method: cannot release un-acquired lock
Exception ignored in: <function _after_at_fork_weak_calls at 0x7f7307550378>
Traceback (most recent call last):
File "/home/python/v3.7.3/lib/python3.7/logging/__init__.py", line
269, in _after_at_fork_weak_calls
_at_fork_weak_calls('release')
File "/home/python/v3.7.3/lib/python3.7/logging/__init__.py", line
254, in _at_fork_weak_calls
for instance in _at_fork_acquire_release_weakset:
File "/home/python/v3.7.3/lib/python3.7/_weakrefset.py", line 60, in __iter__
for itemref in self.data:
RuntimeError: Set changed size during iteration
Exception in thread Thread-1:
Traceback (most recent call last):
File "/home/python/v3.7.3/lib/python3.7/threading.py", line 917, in
_bootstrap_inner
self.run()
File "/home/python/v3.7.3/lib/python3.7/threading.py", line 865, in run
self._target(*self._args, **self._kwargs)
File "./btc.py", line 11, in lockie
h = logging.Handler()
File "/home/python/v3.7.3/lib/python3.7/logging/__init__.py", line
824, in __init__
self.createLock()
File "/home/python/v3.7.3/lib/python3.7/logging/__init__.py", line
847, in createLock
_register_at_fork_acquire_release(self)
File "/home/python/v3.7.3/lib/python3.7/logging/__init__.py", line
250, in _register_at_fork_acquire_release
_at_fork_acquire_release_weakset.add(instance)
File "/home/python/v3.7.3/lib/python3.7/_weakrefset.py", line 83, in add
self._commit_removals()
File "/home/python/v3.7.3/lib/python3.7/_weakrefset.py", line 56, in
_commit_removals
discard(l.pop())
IndexError: pop from empty list
----
import logging
import os
import sys
import threading
def lockie():
while True:
# this adds handle to _at_fork_acquire_release_weakset
#sys.stdout.write(".")
#sys.stdout.flush()
h = logging.Handler()
threading.Thread(target=lockie).start()
for n in range(0,100000):
if n % 100 == 0:
sys.stdout.write("%d" % n)
sys.stdout.flush()
pid = os.fork()
if pid != 0:
os.wait()
else:
os._exit(0)
----------
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue36533>
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