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| author | Sam Gross <colesbury@gmail.com> | 2023-09-19 15:54:29 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2023-09-19 15:54:29 (GMT) |
| commit | 0c89056fe59ac42f09978582479d40e58a236856 (patch) | |
| tree | 06cd5a790da2a6dd3862567419c25572f96ae373 /Misc | |
| parent | 0a31ff0050eec5079fd4c9cafd33b4e3e9afd9ab (diff) | |
| download | cpython-0c89056fe59ac42f09978582479d40e58a236856.zip cpython-0c89056fe59ac42f09978582479d40e58a236856.tar.gz cpython-0c89056fe59ac42f09978582479d40e58a236856.tar.bz2 | |
gh-108724: Add PyMutex and _PyParkingLot APIs (gh-109344)
PyMutex is a one byte lock with fast, inlineable lock and unlock functions for the common uncontended case. The design is based on WebKit's WTF::Lock.
PyMutex is built using the _PyParkingLot APIs, which provides a cross-platform futex-like API (based on WebKit's WTF::ParkingLot). This internal API will be used for building other synchronization primitives used to implement PEP 703, such as one-time initialization and events.
This also includes tests and a mini benchmark in Tools/lockbench/lockbench.py to compare with the existing PyThread_type_lock.
Uncontended acquisition + release:
* Linux (x86-64): PyMutex: 11 ns, PyThread_type_lock: 44 ns
* macOS (arm64): PyMutex: 13 ns, PyThread_type_lock: 18 ns
* Windows (x86-64): PyMutex: 13 ns, PyThread_type_lock: 38 ns
PR Overview:
The primary purpose of this PR is to implement PyMutex, but there are a number of support pieces (described below).
* PyMutex: A 1-byte lock that doesn't require memory allocation to initialize and is generally faster than the existing PyThread_type_lock. The API is internal only for now.
* _PyParking_Lot: A futex-like API based on the API of the same name in WebKit. Used to implement PyMutex.
* _PyRawMutex: A word sized lock used to implement _PyParking_Lot.
* PyEvent: A one time event. This was used a bunch in the "nogil" fork and is useful for testing the PyMutex implementation, so I've included it as part of the PR.
* pycore_llist.h: Defines common operations on doubly-linked list. Not strictly necessary (could do the list operations manually), but they come up frequently in the "nogil" fork. ( Similar to https://man.freebsd.org/cgi/man.cgi?queue)
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Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
Diffstat (limited to 'Misc')
| -rw-r--r-- | Misc/NEWS.d/next/C API/2023-09-12-13-09-36.gh-issue-108724.-yMsC8.rst | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/Misc/NEWS.d/next/C API/2023-09-12-13-09-36.gh-issue-108724.-yMsC8.rst b/Misc/NEWS.d/next/C API/2023-09-12-13-09-36.gh-issue-108724.-yMsC8.rst new file mode 100644 index 0000000..5cddf9b --- /dev/null +++ b/Misc/NEWS.d/next/C API/2023-09-12-13-09-36.gh-issue-108724.-yMsC8.rst @@ -0,0 +1 @@ +Add :c:type:`PyMutex` internal-only lightweight locking API. |