bpo-6721: When os.fork() was called while another thread holds a logging lock, the child process may deadlock when it tries to log. This fixes that by acquiring all logging locks before fork and releasing them afterwards.
A regression test that fails before this change is included.
Within the new unittest itself: There is a small _potential_ due to mixing of fork and a thread in the child process if the parent's thread happened to hold a non-reentrant library call lock (malloc?) when the os.fork() happens. buildbots and time will tell if this actually manifests itself in this test or not. :/ A functionality test that avoids that would be a challenge.
An alternate test that isn't trying to produce the deadlock itself but just checking that the release and acquire calls are made would be the next best alternative if so.
A check has been added in Logger.isEnabledFor() to return False when the logger is disabled. This avoids unnecessary work being done when a disabled logger is used.
This used to be the case on Python 2. Commit
212b590e11 changed the implementation for Python
3, making the `log()` method of LogAdapter call `logger._log()` directly. This
makes nested log adapters not execute their ``process()`` method. This patch
fixes the issue.
Also, now proxying `name`, too, to make `repr()` work with nested log adapters.
New tests added.
Some of the proxied methods use internal Logger state which isn't proxied,
causing failures if an adapter is applied to another adapter.
This commit fixes the issue, adds a new test for the use case.
The ConfigSocketReceiver.serve_until_stopped() method from
logging.config.listen() now calls server_close() (of
socketserver.ThreadingTCPServer) rather than closing manually the
socket.
While this change has no effect yet, it will help to prevent dangling
threads once ThreadingTCPServer.server_close() will join spawned
threads (bpo-31233).
