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bpo-39465: Fix _PyUnicode_FromId() for subinterpreters (GH-20058)

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Make _PyUnicode_FromId() function compatible with subinterpreters.
Each interpreter now has an array of identifier objects (interned
strings decoded from UTF-8).

* Add PyInterpreterState.unicode.identifiers: array of identifiers
  objects.
* Add _PyRuntimeState.unicode_ids used to allocate unique indexes
  to _Py_Identifier.
* Rewrite the _Py_Identifier structure.

Microbenchmark on _PyUnicode_FromId(&PyId_a) with _Py_IDENTIFIER(a):

[ref] 2.42 ns +- 0.00 ns -> [atomic] 3.39 ns +- 0.00 ns: 1.40x slower

This change adds 1 ns per _PyUnicode_FromId() call in average.
This commit is contained in:
Victor Stinner 2020-12-26 00:41:46 +01:00 • committed by GitHub
parent f0853bcedf
commit ba3d67c2fb
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GPG key ID: 4AEE18F83AFDEB23
6 changed files with 102 additions and 37 deletions
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30
Python/pystate.c
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@ -73,18 +73,24 @@ _PyRuntimeState_Init_impl(_PyRuntimeState *runtime)
runtime->interpreters.mutex = PyThread_allocate_lock();
if (runtime->interpreters.mutex == NULL) {
return _PyStatus_ERR("Can't initialize threads for interpreter");
return _PyStatus_NO_MEMORY();
}
runtime->interpreters.next_id = -1;
runtime->xidregistry.mutex = PyThread_allocate_lock();
if (runtime->xidregistry.mutex == NULL) {
return _PyStatus_ERR("Can't initialize threads for cross-interpreter data registry");
return _PyStatus_NO_MEMORY();
}
// Set it to the ID of the main thread of the main interpreter.
runtime->main_thread = PyThread_get_thread_ident();
runtime->unicode_ids.lock = PyThread_allocate_lock();
if (runtime->unicode_ids.lock == NULL) {
return _PyStatus_NO_MEMORY();
}
runtime->unicode_ids.next_index = 0;
return _PyStatus_OK();
}
@ -108,17 +114,17 @@ _PyRuntimeState_Fini(_PyRuntimeState *runtime)
/* Force the allocator used by _PyRuntimeState_Init(). */
PyMemAllocatorEx old_alloc;
_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
if (runtime->interpreters.mutex != NULL) {
PyThread_free_lock(runtime->interpreters.mutex);
runtime->interpreters.mutex = NULL;
#define FREE_LOCK(LOCK) \
if (LOCK != NULL) { \
PyThread_free_lock(LOCK); \
LOCK = NULL; \
}
if (runtime->xidregistry.mutex != NULL) {
PyThread_free_lock(runtime->xidregistry.mutex);
runtime->xidregistry.mutex = NULL;
}
FREE_LOCK(runtime->interpreters.mutex);
FREE_LOCK(runtime->xidregistry.mutex);
FREE_LOCK(runtime->unicode_ids.lock);
#undef FREE_LOCK
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
}
@ -139,12 +145,14 @@ _PyRuntimeState_ReInitThreads(_PyRuntimeState *runtime)
int reinit_interp = _PyThread_at_fork_reinit(&runtime->interpreters.mutex);
int reinit_main_id = _PyThread_at_fork_reinit(&runtime->interpreters.main->id_mutex);
int reinit_xidregistry = _PyThread_at_fork_reinit(&runtime->xidregistry.mutex);
int reinit_unicode_ids = _PyThread_at_fork_reinit(&runtime->unicode_ids.lock);
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
if (reinit_interp < 0
|| reinit_main_id < 0
|| reinit_xidregistry < 0)
|| reinit_xidregistry < 0
|| reinit_unicode_ids < 0)
{
return _PyStatus_ERR("Failed to reinitialize runtime locks");