threading.Lock.acquire(), threading.RLock.acquire() and socket operations now
use a monotonic clock, instead of the system clock, when a timeout is used.
Due to recent changes, a Thread doesn't know that it's over before
someone calls .join() or .is_alive(). That meant repr(Thread)
continued to include "started" (and not "stopped") before one of
those methods was called, even if hours passed since the thread
ended.
Repaired that.
Antoine Pitrou found a variation that worked for him on the
thread+fork tests, and added an important
self._is_stopped = True
to the after-fork code. I confess I don't know why things passed
before. But then mixing fork with threads is insane ;-)
The fix for issue 18808 left us checking two things to be sure a Thread
was done: an Event (._stopped) and a mutex (._tstate_lock). Clumsy &
brittle. This patch removes the Event, leaving just a happy lock :-)
The bulk of the patch removes two excruciating tests, which were
verifying sanity of the internals of the ._stopped Event after a fork.
Thanks to Antoine Pitrou for verifying that's the only real value
these tests had.
One consequence of moving from an Event to a mutex: waiters (threads
calling Thread.join()) used to block each on their own unique mutex
(internal to the ._stopped event), but now all contend on the same
mutex (._tstate_lock). These approaches have different performance
characteristics on different platforms. I don't think it matters in
this context.
