Caw/fix issue 131757 #1
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📝 OVERVIEW
🛠️ TECHNICAL DETAILS
🏗️ ARCHITECTURAL IMPACT
🚀 IMPLEMENTATION HIGHLIGHTS
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| File | Change Type | Changes | Summary |
|---|---|---|---|
Misc/NEWS.d/next/Library/2025-03-26-10-56-22.gh-issue-131757.pFRdmN.rst |
Added | +1/-0 | The change modifies functools.lru_cache to execute the cached function's body without holding the cache's internal lock, allowing concurrent execution of the decorated function in parallel threads. This uses a context manager to temporarily release the lock during the function's execution, improving concurrency while maintaining cache consistency. |
Modules/_functoolsmodule.c |
Modified | +92/-37 | The changes implement atomic operations for hit/miss counters and critical sections in LRU cache logic, affecting uncached_lru_cache_wrapper, infinite_lru_cache_wrapper, and bounded_lru_cache_wrapper by replacing direct increments with FT_ATOMIC_ADD_SSIZE (using _Py_atomic_add_ssize when GIL is disabled) and restructuring bounded cache handling into lock-protected functions, while cache_info/cache_clear now use atomic loads/stores for thread-safe state access. |
mansidhall-CAW
commented
Mar 28, 2025
| @@ -1175,7 +1182,7 @@ uncached_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwd | |||
| { | |||
| PyObject *result;< 8000 /span> | |||
|
|
|||
| self->misses++; | |||
| FT_ATOMIC_ADD_SSIZE(self->misses, 1); | |||
There was a problem hiding this comment.
The non-bounded path incorrectly increments misses and calls the function before checking the cache. This bypasses the cache entirely, leading to incorrect behavior. The cache check must occur before calling the function.
SUGGESTION:
- FT_ATOMIC_ADD_SSIZE(self->misses, 1);
- result = PyObject_Call(self->func, args, kwds);
+ // Move cache check before function call
+ // Restore original logic from old code
+ // (create key, check cache, increment hits/misses accordingly)
{
"lastReviewedCommitId": "34f7fe7d3e46506b4d670b8712573b9c20c3999b",
"reviewedCommitIds": [
"34f7fe7d3e46506b4d670b8712573b9c20c3999b"
]
} |
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python#131758