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gh-100227: Add a Granular Lock for _PyRuntime.imports.extensions.dict (gh-103460) 

The lock is unnecessary as long as there's a GIL, but completely
necessary with a per-interpreter GIL.
This commit is contained in:
Eric Snow 2023-04-24 21:09:35 -06:00 committed by GitHub
parent b934f97850
commit d8627999d8
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 16 additions and 4 deletions
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2
Include/internal/pycore_import.h
View File

@ -19,6 +19,8 @@ struct _import_runtime_state {
used exclusively for when the extensions dict is access/modified
from an arbitrary thread. */
PyThreadState main_tstate;
/* A lock to guard the dict. */
PyThread_type_lock mutex;
/* A dict mapping (filename, name) to PyModuleDef for modules.
Only legacy (single-phase init) extension modules are added
and only if they support multiple initialization (m_size >- 0)

13
Python/import.c
View File

@ -413,8 +413,11 @@ remove_module(PyThreadState *tstate, PyObject *name)
Py_ssize_t
_PyImport_GetNextModuleIndex(void)
{
PyThread_acquire_lock(EXTENSIONS.mutex, WAIT_LOCK);
LAST_MODULE_INDEX++;
return LAST_MODULE_INDEX;
Py_ssize_t index = LAST_MODULE_INDEX;
PyThread_release_lock(EXTENSIONS.mutex);
return index;
}
static const char *
@ -703,6 +706,7 @@ _PyImport_ClearModulesByIndex(PyInterpreterState *interp)
const char *
_PyImport_ResolveNameWithPackageContext(const char *name)
{
PyThread_acquire_lock(EXTENSIONS.mutex, WAIT_LOCK);
if (PKGCONTEXT != NULL) {
const char *p = strrchr(PKGCONTEXT, '.');
if (p != NULL && strcmp(name, p+1) == 0) {
@ -710,14 +714,17 @@ _PyImport_ResolveNameWithPackageContext(const char *name)
PKGCONTEXT = NULL;
}
}
PyThread_release_lock(EXTENSIONS.mutex);
return name;
}
const char *
_PyImport_SwapPackageContext(const char *newcontext)
{
PyThread_acquire_lock(EXTENSIONS.mutex, WAIT_LOCK);
const char *oldcontext = PKGCONTEXT;
PKGCONTEXT = newcontext;
PyThread_release_lock(EXTENSIONS.mutex);
return oldcontext;
}
@ -865,13 +872,13 @@ gets even messier.
static inline void
extensions_lock_acquire(void)
{
// XXX For now the GIL is sufficient.
PyThread_acquire_lock(_PyRuntime.imports.extensions.mutex, WAIT_LOCK);
}
static inline void
extensions_lock_release(void)
{
// XXX For now the GIL is sufficient.
PyThread_release_lock(_PyRuntime.imports.extensions.mutex);
}
/* Magic for extension modules (built-in as well as dynamically

5
Python/pystate.c
View File

@ -380,7 +380,7 @@ _Py_COMP_DIAG_IGNORE_DEPR_DECLS
static const _PyRuntimeState initial = _PyRuntimeState_INIT(_PyRuntime);
_Py_COMP_DIAG_POP
#define NUMLOCKS 4
#define NUMLOCKS 5
static int
alloc_for_runtime(PyThread_type_lock locks[NUMLOCKS])
@ -434,6 +434,7 @@ init_runtime(_PyRuntimeState *runtime,
&runtime->xidregistry.mutex,
&runtime->getargs.mutex,
&runtime->unicode_state.ids.lock,
&runtime->imports.extensions.mutex,
};
for (int i = 0; i < NUMLOCKS; i++) {
assert(locks[i] != NULL);
@ -518,6 +519,7 @@ _PyRuntimeState_Fini(_PyRuntimeState *runtime)
&runtime->xidregistry.mutex,
&runtime->getargs.mutex,
&runtime->unicode_state.ids.lock,
&runtime->imports.extensions.mutex,
};
for (int i = 0; i < NUMLOCKS; i++) {
FREE_LOCK(*lockptrs[i]);
@ -546,6 +548,7 @@ _PyRuntimeState_ReInitThreads(_PyRuntimeState *runtime)
&runtime->xidregistry.mutex,
&runtime->getargs.mutex,
&runtime->unicode_state.ids.lock,
&runtime->imports.extensions.mutex,
};
int reinit_err = 0;
for (int i = 0; i < NUMLOCKS; i++) {