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| author | Ryan Hileman <lunixbochs@gmail.com> | 2021-06-07 13:26:02 -0700 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2021-06-07 21:26:02 +0100 |
| commit | 449e6f0ef395231e3abe467f910b02d7f075c27f (patch) | |
| tree | e35ceef7ead7421c8fa974a118367b2bf1824e89 | |
| parent | 2ab27c4af4ddf7528e1375e77c787c7fbb09b5e6 (diff) | |
| download | cpython-449e6f0ef395231e3abe467f910b02d7f075c27f.tar.gz cpython-449e6f0ef395231e3abe467f910b02d7f075c27f.zip | |
bpo-41299: Reduce lag in Windows threading timeouts by using a higher precision time source (GH-26568)
| -rw-r--r-- | Misc/NEWS.d/next/Windows/2021-06-06-16-36-13.bpo-41299.Rg-vb_.rst | 1 | ||||
| -rw-r--r-- | Python/thread_nt.h | 14 |
2 files changed, 11 insertions, 4 deletions
diff --git a/Misc/NEWS.d/next/Windows/2021-06-06-16-36-13.bpo-41299.Rg-vb_.rst b/Misc/NEWS.d/next/Windows/2021-06-06-16-36-13.bpo-41299.Rg-vb_.rst new file mode 100644 index 00000000000..71f700ffa15 --- /dev/null +++ b/Misc/NEWS.d/next/Windows/2021-06-06-16-36-13.bpo-41299.Rg-vb_.rst @@ -0,0 +1 @@ +Fix 16ms jitter when using timeouts in :mod:`threading`, such as with :meth:`threading.Lock.acquire` or :meth:`threading.Condition.wait`. diff --git a/Python/thread_nt.h b/Python/thread_nt.h index 05b982d32dc..0ce5e94f89b 100644 --- a/Python/thread_nt.h +++ b/Python/thread_nt.h @@ -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) { |