From 5c9ee498c6f4b75e0e020f17b6860309c3b7e11e Mon Sep 17 00:00:00 2001 From: Eric Snow Date: Mon, 8 May 2023 13:15:09 -0600 Subject: [PATCH] gh-99113: A Per-Interpreter GIL! (gh-104210) This is the culmination of PEP 684 (and of my 8-year long multi-core Python project)! Each subinterpreter may now be created with its own GIL (via Py_NewInterpreterFromConfig()). If not so configured then the interpreter will share with the main interpreter--the status quo since subinterpreters were added decades ago. The main interpreter always has its own GIL and subinterpreters from Py_NewInterpreter() will always share with the main interpreter. --- Include/internal/pycore_ceval.h | 3 +- Include/internal/pycore_ceval_state.h | 3 - Include/internal/pycore_interp.h | 3 + Include/internal/pycore_runtime.h | 2 - ...3-05-05-12-14-47.gh-issue-99113.-RAdnv.rst | 6 ++ Python/ceval_gil.c | 55 +++++-------------- Python/pystate.c | 4 +- 7 files changed, 24 insertions(+), 52 deletions(-) create mode 100644 Misc/NEWS.d/next/Core and Builtins/2023-05-05-12-14-47.gh-issue-99113.-RAdnv.rst diff --git a/Include/internal/pycore_ceval.h b/Include/internal/pycore_ceval.h index 9fd8571cbc87f4..3c8b368bd2af4e 100644 --- a/Include/internal/pycore_ceval.h +++ b/Include/internal/pycore_ceval.h @@ -21,8 +21,7 @@ struct _ceval_runtime_state; extern void _Py_FinishPendingCalls(PyThreadState *tstate); -extern void _PyEval_InitRuntimeState(struct _ceval_runtime_state *); -extern void _PyEval_InitState(struct _ceval_state *, PyThread_type_lock); +extern void _PyEval_InitState(PyInterpreterState *, PyThread_type_lock); extern void _PyEval_FiniState(struct _ceval_state *ceval); PyAPI_FUNC(void) _PyEval_SignalReceived(PyInterpreterState *interp); PyAPI_FUNC(int) _PyEval_AddPendingCall( diff --git a/Include/internal/pycore_ceval_state.h b/Include/internal/pycore_ceval_state.h index 4781dd5735dcf6..b352801673c40a 100644 --- a/Include/internal/pycore_ceval_state.h +++ b/Include/internal/pycore_ceval_state.h @@ -49,9 +49,6 @@ struct _ceval_runtime_state { the main thread of the main interpreter can handle signals: see _Py_ThreadCanHandleSignals(). */ _Py_atomic_int signals_pending; - - /* This is (only) used indirectly through PyInterpreterState.ceval.gil. */ - struct _gil_runtime_state gil; }; #ifdef PY_HAVE_PERF_TRAMPOLINE diff --git a/Include/internal/pycore_interp.h b/Include/internal/pycore_interp.h index 7276ce35ba68f0..527b2121148f4c 100644 --- a/Include/internal/pycore_interp.h +++ b/Include/internal/pycore_interp.h @@ -178,6 +178,9 @@ struct _is { basis. Also see _PyRuntimeState regarding the various mutex fields. */ + /* The per-interpreter GIL, which might not be used. */ + struct _gil_runtime_state _gil; + /* the initial PyInterpreterState.threads.head */ PyThreadState _initial_thread; }; diff --git a/Include/internal/pycore_runtime.h b/Include/internal/pycore_runtime.h index d1b165d0ab9c38..6e06e874711bc2 100644 --- a/Include/internal/pycore_runtime.h +++ b/Include/internal/pycore_runtime.h @@ -32,8 +32,6 @@ struct _getargs_runtime_state { struct _PyArg_Parser *static_parsers; }; -/* ceval state */ - /* GIL state */ struct _gilstate_runtime_state { diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-05-05-12-14-47.gh-issue-99113.-RAdnv.rst b/Misc/NEWS.d/next/Core and Builtins/2023-05-05-12-14-47.gh-issue-99113.-RAdnv.rst new file mode 100644 index 00000000000000..42e26cb27b6e01 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2023-05-05-12-14-47.gh-issue-99113.-RAdnv.rst @@ -0,0 +1,6 @@ +The GIL is now (optionally) per-interpreter. This is the fundamental change +for PEP 684. This is all made possible by virtue of the isolated state of +each interpreter in the process. The behavior of the main interpreter +remains unchanged. Likewise, interpreters created using +``Py_NewInterpreter()`` are not affected. To get an interpreter with its +own GIL, call ``Py_NewInterpreterFromConfig()``. diff --git a/Python/ceval_gil.c b/Python/ceval_gil.c index 9958856bae8019..42e1436bc9130d 100644 --- a/Python/ceval_gil.c +++ b/Python/ceval_gil.c @@ -464,8 +464,7 @@ take_gil(PyThreadState *tstate) void _PyEval_SetSwitchInterval(unsigned long microseconds) { - /* XXX per-interpreter GIL */ - PyInterpreterState *interp = _PyInterpreterState_Main(); + PyInterpreterState *interp = _PyInterpreterState_Get(); struct _gil_runtime_state *gil = interp->ceval.gil; assert(gil != NULL); gil->interval = microseconds; @@ -473,8 +472,7 @@ void _PyEval_SetSwitchInterval(unsigned long microseconds) unsigned long _PyEval_GetSwitchInterval(void) { - /* XXX per-interpreter GIL */ - PyInterpreterState *interp = _PyInterpreterState_Main(); + PyInterpreterState *interp = _PyInterpreterState_Get(); struct _gil_runtime_state *gil = interp->ceval.gil; assert(gil != NULL); return gil->interval; @@ -484,7 +482,9 @@ unsigned long _PyEval_GetSwitchInterval(void) int _PyEval_ThreadsInitialized(void) { - /* XXX per-interpreter GIL */ + /* XXX This is only needed for an assert in PyGILState_Ensure(), + * which currently does not work with subinterpreters. + * Thus we only use the main interpreter. */ PyInterpreterState *interp = _PyInterpreterState_Main(); if (interp == NULL) { return 0; @@ -532,27 +532,16 @@ _PyEval_InitGIL(PyThreadState *tstate, int own_gil) assert(tstate->interp->ceval.gil == NULL); int locked; if (!own_gil) { + /* The interpreter will share the main interpreter's instead. */ PyInterpreterState *main_interp = _PyInterpreterState_Main(); assert(tstate->interp != main_interp); struct _gil_runtime_state *gil = main_interp->ceval.gil; init_shared_gil(tstate->interp, gil); locked = current_thread_holds_gil(gil, tstate); } - /* XXX per-interpreter GIL */ - else if (!_Py_IsMainInterpreter(tstate->interp)) { - /* Currently, the GIL is shared by all interpreters, - and only the main interpreter is responsible to create - and destroy it. */ - struct _gil_runtime_state *main_gil = _PyInterpreterState_Main()->ceval.gil; - init_shared_gil(tstate->interp, main_gil); - // XXX For now we lie. - tstate->interp->ceval.own_gil = 1; - locked = current_thread_holds_gil(main_gil, tstate); - } else { PyThread_init_thread(); - // XXX per-interpreter GIL: switch to interp->_gil. - init_own_gil(tstate->interp, &tstate->interp->runtime->ceval.gil); + init_own_gil(tstate->interp, &tstate->interp->_gil); locked = 0; } if (!locked) { @@ -565,7 +554,8 @@ _PyEval_InitGIL(PyThreadState *tstate, int own_gil) void _PyEval_FiniGIL(PyInterpreterState *interp) { - if (interp->ceval.gil == NULL) { + struct _gil_runtime_state *gil = interp->ceval.gil; + if (gil == NULL) { /* It was already finalized (or hasn't been initialized yet). */ assert(!interp->ceval.own_gil); return; @@ -573,24 +563,13 @@ _PyEval_FiniGIL(PyInterpreterState *interp) else if (!interp->ceval.own_gil) { #ifdef Py_DEBUG PyInterpreterState *main_interp = _PyInterpreterState_Main(); - assert(interp != main_interp); + assert(main_interp != NULL && interp != main_interp); assert(interp->ceval.gil == main_interp->ceval.gil); #endif interp->ceval.gil = NULL; return; } - /* XXX per-interpreter GIL */ - struct _gil_runtime_state *gil = &interp->runtime->ceval.gil; - if (!_Py_IsMainInterpreter(interp)) { - /* Currently, the GIL is shared by all interpreters, - and only the main interpreter is responsible to create - and destroy it. */ - assert(interp->ceval.gil == gil); - interp->ceval.gil = NULL; - return; - } - if (!gil_created(gil)) { /* First Py_InitializeFromConfig() call: the GIL doesn't exist yet: do nothing. */ @@ -974,21 +953,13 @@ Py_MakePendingCalls(void) return 0; } -/* The interpreter's recursion limit */ - void -_PyEval_InitRuntimeState(struct _ceval_runtime_state *ceval) +_PyEval_InitState(PyInterpreterState *interp, PyThread_type_lock pending_lock) { - /* XXX per-interpreter GIL */ - _gil_initialize(&ceval->gil); -} + _gil_initialize(&interp->_gil); -void -_PyEval_InitState(struct _ceval_state *ceval, PyThread_type_lock pending_lock) -{ - struct _pending_calls *pending = &ceval->pending; + struct _pending_calls *pending = &interp->ceval.pending; assert(pending->lock == NULL); - pending->lock = pending_lock; } diff --git a/Python/pystate.c b/Python/pystate.c index f14934361dab78..26debf1f88b94a 100644 --- a/Python/pystate.c +++ b/Python/pystate.c @@ -425,8 +425,6 @@ init_runtime(_PyRuntimeState *runtime, runtime->open_code_userdata = open_code_userdata; runtime->audit_hook_head = audit_hook_head; - _PyEval_InitRuntimeState(&runtime->ceval); - PyPreConfig_InitPythonConfig(&runtime->preconfig); PyThread_type_lock *lockptrs[NUMLOCKS] = { @@ -682,7 +680,7 @@ init_interpreter(PyInterpreterState *interp, memcpy(&interp->obmalloc.pools.used, temp, sizeof(temp)); } - _PyEval_InitState(&interp->ceval, pending_lock); + _PyEval_InitState(interp, pending_lock); _PyGC_InitState(&interp->gc); PyConfig_InitPythonConfig(&interp->config); _PyType_InitCache(interp);