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gh-114271: Make _thread.ThreadHandle thread-safe in free-threaded builds #115190

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Merged
gpshead merged 21 commits into from
Mar 1, 2024
Merged

gh-114271: Make _thread.ThreadHandle thread-safe in free-threaded builds #115190

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cf6491c
Make `_thread.ThreadHandle` thread-safe in free-threaded builds
mpage Feb 8, 2024
e86dde8
Don't use PyOnceFlag post fork
mpage Feb 9, 2024
9a61e20
Check for self-join outside of the once flag
mpage Feb 9, 2024
bcf66ce
Fix grammar and formatting
mpage Feb 9, 2024
7f9720d
Update comment.
mpage Feb 9, 2024
092c2eb
Account for handles being cleared after fork
mpage Feb 10, 2024
77da31d
Move implementations of `_PyEventRc` functions out of header
mpage Feb 12, 2024
321a4e0
Track all states of the handle in the enum
mpage Feb 12, 2024
cd0372c
Remove `detach()` method
mpage Feb 12, 2024
7badb2d
Don't need to atomically initialize state in ThreadHandle ctor
mpage Feb 13, 2024
9d35990
Remove unneeded function
mpage Feb 13, 2024
e554c5e
Don't need atomics in dtor
mpage Feb 13, 2024
147a192
Elaborate on use of `thread_is_exiting` in `ThreadHandleObject` defin…
mpage Feb 13, 2024
1fe27ce
Use sequential consistency for operations on state
mpage Feb 14, 2024
9ec6d23
Merge branch 'main' into gh-114271-_thread-ThreadHandle
mpage Feb 14, 2024
a46b727
Remove `_join_lock` attribute
mpage Feb 26, 2024
61d9fa9
Add reference to more details for self-join test
mpage Feb 26, 2024
f6bfa08
Assign explicit values for ThreadHandle states
mpage Feb 27, 2024
1cc0f2e
Detail why non-atomic state access is safe in the destructor
mpage Feb 27, 2024
3fbf119
Document the purpose of bootstate
mpage Feb 27, 2024
9d21444
Mark handles running before decrefing args
mpage Feb 27, 2024
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Move implementations of _PyEventRc functions out of header
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@mpage
mpage committed Feb 12, 2024
commit 77da31d49718845190f435b56f5239e04281dac5
26 changes: 3 additions & 23 deletions Include/internal/pycore_lock.h
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Original file line number Diff line number Diff line change
Expand Up @@ -158,29 +158,9 @@ typedef struct _PyEventRc {
Py_ssize_t refcount;
} _PyEventRc;

static inline _PyEventRc *
_PyEventRc_New(void)
{
_PyEventRc *erc = (_PyEventRc *)PyMem_RawCalloc(1, sizeof(_PyEventRc));
if (erc != NULL) {
erc->refcount = 1;
}
return erc;
}

static inline void
_PyEventRc_Incref(_PyEventRc *erc)
{
_Py_atomic_add_ssize(&erc->refcount, 1);
}

static inline void
_PyEventRc_Decref(_PyEventRc *erc)
{
if (_Py_atomic_add_ssize(&erc->refcount, -1) == 1) {
PyMem_RawFree(erc);
}
}
_PyEventRc *_PyEventRc_New(void);
void _PyEventRc_Incref(_PyEventRc *erc);
void _PyEventRc_Decref(_PyEventRc *erc);

// _PyRawMutex implements a word-sized mutex that that does not depend on the
// parking lot API, and therefore can be used in the parking lot
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24 changes: 24 additions & 0 deletions Python/lock.c
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Expand Up @@ -303,6 +303,30 @@ PyEvent_WaitTimed(PyEvent *evt, _PyTime_t timeout_ns)
}
}

_PyEventRc *
_PyEventRc_New(void)
{
_PyEventRc *erc = (_PyEventRc *)PyMem_RawCalloc(1, sizeof(_PyEventRc));
if (erc != NULL) {
erc->refcount = 1;
}
return erc;
}

void
_PyEventRc_Incref(_PyEventRc *erc)
{
_Py_atomic_add_ssize(&erc->refcount, 1);
}

void
_PyEventRc_Decref(_PyEventRc *erc)
{
if (_Py_atomic_add_ssize(&erc->refcount, -1) == 1) {
PyMem_RawFree(erc);
}
}

static int
unlock_once(_PyOnceFlag *o, int res)
{
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