mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-07-07 19:35:27 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 8

bpo-41299: Reduce lag in Windows threading timeouts by using a higher precision time source (GH-26568) (GH-26580)

Browse source 
(cherry picked from commit 449e6f0ef3)

Co-authored-by: Ryan Hileman <lunixbochs@gmail.com>

Co-authored-by: Ryan Hileman <lunixbochs@gmail.com>
This commit is contained in:
Miss Islington (bot) 2021-06-20 13:12:27 -07:00 • committed by GitHub
parent f87d2038fa
commit 8673b77e25
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
2 changed files with 11 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

1
Misc/NEWS.d/next/Windows/2021-06-06-16-36-13.bpo-41299.Rg-vb_.rst Normal file
View file

@ -0,0 +1 @@
Fix 16ms jitter when using timeouts in :mod:`threading`, such as with :meth:`threading.Lock.acquire` or :meth:`threading.Condition.wait`.

14
Python/thread_nt.h
View file

@ -76,16 +76,22 @@ EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)
}
} else if (milliseconds != 0) {
/* wait at least until the target */
ULONGLONG now, target = GetTickCount64() + milliseconds;
_PyTime_t now = _PyTime_GetPerfCounter();
if (now <= 0) {
Py_FatalError("_PyTime_GetPerfCounter() == 0");
}
_PyTime_t nanoseconds = _PyTime_FromNanoseconds((_PyTime_t)milliseconds * 1000000);
_PyTime_t target = now + nanoseconds;
while (mutex->locked) {
if (PyCOND_TIMEDWAIT(&mutex->cv, &mutex->cs, (long long)milliseconds*1000) < 0) {
_PyTime_t microseconds = _PyTime_AsMicroseconds(nanoseconds, _PyTime_ROUND_TIMEOUT);
if (PyCOND_TIMEDWAIT(&mutex->cv, &mutex->cs, microseconds) < 0) {
result = WAIT_FAILED;
break;
}
now = GetTickCount64();
now = _PyTime_GetPerfCounter();
if (target <= now)
break;
milliseconds = (DWORD)(target-now);
nanoseconds = target - now;
}
}
if (!mutex->locked) {