diff options
Diffstat (limited to 'contrib/tools/python3/Modules/_threadmodule.c')
| -rw-r--r-- | contrib/tools/python3/Modules/_threadmodule.c | 1901 |
1 files changed, 1369 insertions, 532 deletions
diff --git a/contrib/tools/python3/Modules/_threadmodule.c b/contrib/tools/python3/Modules/_threadmodule.c index 366ee6186de..bc9433afe41 100644 --- a/contrib/tools/python3/Modules/_threadmodule.c +++ b/contrib/tools/python3/Modules/_threadmodule.c @@ -1,15 +1,18 @@ - /* Thread module */ /* Interface to Sjoerd's portable C thread library */ #include "Python.h" #include "pycore_interp.h" // _PyInterpreterState.threads.count +#include "pycore_lock.h" #include "pycore_moduleobject.h" // _PyModule_GetState() +#include "pycore_modsupport.h" // _PyArg_NoKeywords() #include "pycore_pylifecycle.h" #include "pycore_pystate.h" // _PyThreadState_SetCurrent() -#include <stddef.h> // offsetof() -#include "structmember.h" // PyMemberDef +#include "pycore_sysmodule.h" // _PySys_GetOptionalAttr() +#include "pycore_time.h" // _PyTime_FromSeconds() +#include "pycore_weakref.h" // _PyWeakref_GET_REF() +#include <stddef.h> // offsetof() #ifdef HAVE_SIGNAL_H # include <signal.h> // SIGINT #endif @@ -17,16 +20,20 @@ // ThreadError is just an alias to PyExc_RuntimeError #define ThreadError PyExc_RuntimeError - // Forward declarations static struct PyModuleDef thread_module; - +// Module state typedef struct { PyTypeObject *excepthook_type; PyTypeObject *lock_type; PyTypeObject *local_type; PyTypeObject *local_dummy_type; + PyTypeObject *thread_handle_type; + + // Linked list of handles to all non-daemon threads created by the + // threading module. We wait for these to finish at shutdown. + struct llist_node shutdown_handles; } thread_module_state; static inline thread_module_state* @@ -37,109 +44,715 @@ get_thread_state(PyObject *module) return (thread_module_state *)state; } +// _ThreadHandle type -/* Lock objects */ +// Handles state transitions according to the following diagram: +// +// NOT_STARTED -> STARTING -> RUNNING -> DONE +// | ^ +// | | +// +----- error --------+ +typedef enum { + THREAD_HANDLE_NOT_STARTED = 1, + THREAD_HANDLE_STARTING = 2, + THREAD_HANDLE_RUNNING = 3, + THREAD_HANDLE_DONE = 4, +} ThreadHandleState; +// A handle to wait for thread completion. +// +// This may be used to wait for threads that were spawned by the threading +// module as well as for the "main" thread of the threading module. In the +// former case an OS thread, identified by the `os_handle` field, will be +// associated with the handle. The handle "owns" this thread and ensures that +// the thread is either joined or detached after the handle is destroyed. +// +// Joining the handle is idempotent; the underlying OS thread, if any, is +// joined or detached only once. Concurrent join operations are serialized +// until it is their turn to execute or an earlier operation completes +// successfully. Once a join has completed successfully all future joins +// complete immediately. +// +// This must be separately reference counted because it may be destroyed +// in `thread_run()` after the PyThreadState has been destroyed. +typedef struct { + struct llist_node node; // linked list node (see _pythread_runtime_state) + + // linked list node (see thread_module_state) + struct llist_node shutdown_node; + + // The `ident`, `os_handle`, `has_os_handle`, and `state` fields are + // protected by `mutex`. + PyThread_ident_t ident; + PyThread_handle_t os_handle; + int has_os_handle; + + // Holds a value from the `ThreadHandleState` enum. + int state; + + PyMutex mutex; + + // Set immediately before `thread_run` returns to indicate that the OS + // thread is about to exit. This is used to avoid false positives when + // detecting self-join attempts. See the comment in `ThreadHandle_join()` + // for a more detailed explanation. + PyEvent thread_is_exiting; + + // Serializes calls to `join` and `set_done`. + _PyOnceFlag once; + + Py_ssize_t refcount; +} ThreadHandle; + +static inline int +get_thread_handle_state(ThreadHandle *handle) +{ + PyMutex_Lock(&handle->mutex); + int state = handle->state; + PyMutex_Unlock(&handle->mutex); + return state; +} + +static inline void +set_thread_handle_state(ThreadHandle *handle, ThreadHandleState state) +{ + PyMutex_Lock(&handle->mutex); + handle->state = state; + PyMutex_Unlock(&handle->mutex); +} + +static PyThread_ident_t +ThreadHandle_ident(ThreadHandle *handle) +{ + PyMutex_Lock(&handle->mutex); + PyThread_ident_t ident = handle->ident; + PyMutex_Unlock(&handle->mutex); + return ident; +} + +static int +ThreadHandle_get_os_handle(ThreadHandle *handle, PyThread_handle_t *os_handle) +{ + PyMutex_Lock(&handle->mutex); + int has_os_handle = handle->has_os_handle; + if (has_os_handle) { + *os_handle = handle->os_handle; + } + PyMutex_Unlock(&handle->mutex); + return has_os_handle; +} + +static void +add_to_shutdown_handles(thread_module_state *state, ThreadHandle *handle) +{ + HEAD_LOCK(&_PyRuntime); + llist_insert_tail(&state->shutdown_handles, &handle->shutdown_node); + HEAD_UNLOCK(&_PyRuntime); +} + +static void +clear_shutdown_handles(thread_module_state *state) +{ + HEAD_LOCK(&_PyRuntime); + struct llist_node *node; + llist_for_each_safe(node, &state->shutdown_handles) { + llist_remove(node); + } + HEAD_UNLOCK(&_PyRuntime); +} + +static void +remove_from_shutdown_handles(ThreadHandle *handle) +{ + HEAD_LOCK(&_PyRuntime); + if (handle->shutdown_node.next != NULL) { + llist_remove(&handle->shutdown_node); + } + HEAD_UNLOCK(&_PyRuntime); +} + +static ThreadHandle * +ThreadHandle_new(void) +{ + ThreadHandle *self = + (ThreadHandle *)PyMem_RawCalloc(1, sizeof(ThreadHandle)); + if (self == NULL) { + PyErr_NoMemory(); + return NULL; + } + self->ident = 0; + self->os_handle = 0; + self->has_os_handle = 0; + self->thread_is_exiting = (PyEvent){0}; + self->mutex = (PyMutex){_Py_UNLOCKED}; + self->once = (_PyOnceFlag){0}; + self->state = THREAD_HANDLE_NOT_STARTED; + self->refcount = 1; + + HEAD_LOCK(&_PyRuntime); + llist_insert_tail(&_PyRuntime.threads.handles, &self->node); + HEAD_UNLOCK(&_PyRuntime); + + return self; +} + +static void +ThreadHandle_incref(ThreadHandle *self) +{ + _Py_atomic_add_ssize(&self->refcount, 1); +} + +static int +detach_thread(ThreadHandle *self) +{ + if (!self->has_os_handle) { + return 0; + } + // This is typically short so no need to release the GIL + if (PyThread_detach_thread(self->os_handle)) { + fprintf(stderr, "detach_thread: failed detaching thread\n"); + return -1; + } + return 0; +} + +// NB: This may be called after the PyThreadState in `thread_run` has been +// deleted; it cannot call anything that relies on a valid PyThreadState +// existing. +static void +ThreadHandle_decref(ThreadHandle *self) +{ + if (_Py_atomic_add_ssize(&self->refcount, -1) > 1) { + return; + } + + // Remove ourself from the global list of handles + HEAD_LOCK(&_PyRuntime); + if (self->node.next != NULL) { + llist_remove(&self->node); + } + HEAD_UNLOCK(&_PyRuntime); + + assert(self->shutdown_node.next == NULL); + + // It's safe to access state non-atomically: + // 1. This is the destructor; nothing else holds a reference. + // 2. The refcount going to zero is a "synchronizes-with" event; all + // changes from other threads are visible. + if (self->state == THREAD_HANDLE_RUNNING && !detach_thread(self)) { + self->state = THREAD_HANDLE_DONE; + } + + PyMem_RawFree(self); +} + +void +_PyThread_AfterFork(struct _pythread_runtime_state *state) +{ + // gh-115035: We mark ThreadHandles as not joinable early in the child's + // after-fork handler. We do this before calling any Python code to ensure + // that it happens before any ThreadHandles are deallocated, such as by a + // GC cycle. + PyThread_ident_t current = PyThread_get_thread_ident_ex(); + + struct llist_node *node; + llist_for_each_safe(node, &state->handles) { + ThreadHandle *handle = llist_data(node, ThreadHandle, node); + if (handle->ident == current) { + continue; + } + + // Keep handles for threads that have not been started yet. They are + // safe to start in the child process. + if (handle->state == THREAD_HANDLE_NOT_STARTED) { + continue; + } + + // Mark all threads as done. Any attempts to join or detach the + // underlying OS thread (if any) could crash. We are the only thread; + // it's safe to set this non-atomically. + handle->state = THREAD_HANDLE_DONE; + handle->once = (_PyOnceFlag){_Py_ONCE_INITIALIZED}; + handle->mutex = (PyMutex){_Py_UNLOCKED}; + _PyEvent_Notify(&handle->thread_is_exiting); + llist_remove(node); + remove_from_shutdown_handles(handle); + } +} + +// bootstate is used to "bootstrap" new threads. Any arguments needed by +// `thread_run()`, which can only take a single argument due to platform +// limitations, are contained in bootstate. +struct bootstate { + PyThreadState *tstate; + PyObject *func; + PyObject *args; + PyObject *kwargs; + ThreadHandle *handle; + PyEvent handle_ready; +}; + +static void +thread_bootstate_free(struct bootstate *boot, int decref) +{ + if (decref) { + Py_DECREF(boot->func); + Py_DECREF(boot->args); + Py_XDECREF(boot->kwargs); + } + ThreadHandle_decref(boot->handle); + PyMem_RawFree(boot); +} + +static void +thread_run(void *boot_raw) +{ + struct bootstate *boot = (struct bootstate *) boot_raw; + PyThreadState *tstate = boot->tstate; + + // Wait until the handle is marked as running + PyEvent_Wait(&boot->handle_ready); + + // `handle` needs to be manipulated after bootstate has been freed + ThreadHandle *handle = boot->handle; + ThreadHandle_incref(handle); + + // gh-108987: If _thread.start_new_thread() is called before or while + // Python is being finalized, thread_run() can called *after*. + // _PyRuntimeState_SetFinalizing() is called. At this point, all Python + // threads must exit, except of the thread calling Py_Finalize() which + // holds the GIL and must not exit. + // + // At this stage, tstate can be a dangling pointer (point to freed memory), + // it's ok to call _PyThreadState_MustExit() with a dangling pointer. + if (_PyThreadState_MustExit(tstate)) { + // Don't call PyThreadState_Clear() nor _PyThreadState_DeleteCurrent(). + // These functions are called on tstate indirectly by Py_Finalize() + // which calls _PyInterpreterState_Clear(). + // + // Py_DECREF() cannot be called because the GIL is not held: leak + // references on purpose. Python is being finalized anyway. + thread_bootstate_free(boot, 0); + goto exit; + } + + _PyThreadState_Bind(tstate); + PyEval_AcquireThread(tstate); + _Py_atomic_add_ssize(&tstate->interp->threads.count, 1); + + PyObject *res = PyObject_Call(boot->func, boot->args, boot->kwargs); + if (res == NULL) { + if (PyErr_ExceptionMatches(PyExc_SystemExit)) + /* SystemExit is ignored silently */ + PyErr_Clear(); + else { + PyErr_FormatUnraisable( + "Exception ignored in thread started by %R", boot->func); + } + } + else { + Py_DECREF(res); + } + + thread_bootstate_free(boot, 1); + + _Py_atomic_add_ssize(&tstate->interp->threads.count, -1); + PyThreadState_Clear(tstate); + _PyThreadState_DeleteCurrent(tstate); + +exit: + // Don't need to wait for this thread anymore + remove_from_shutdown_handles(handle); + + _PyEvent_Notify(&handle->thread_is_exiting); + ThreadHandle_decref(handle); + + // bpo-44434: Don't call explicitly PyThread_exit_thread(). On Linux with + // the glibc, pthread_exit() can abort the whole process if dlopen() fails + // to open the libgcc_s.so library (ex: EMFILE error). + return; +} + +static int +force_done(ThreadHandle *handle) +{ + assert(get_thread_handle_state(handle) == THREAD_HANDLE_STARTING); + _PyEvent_Notify(&handle->thread_is_exiting); + set_thread_handle_state(handle, THREAD_HANDLE_DONE); + return 0; +} + +static int +ThreadHandle_start(ThreadHandle *self, PyObject *func, PyObject *args, + PyObject *kwargs) +{ + // Mark the handle as starting to prevent any other threads from doing so + PyMutex_Lock(&self->mutex); + if (self->state != THREAD_HANDLE_NOT_STARTED) { + PyMutex_Unlock(&self->mutex); + PyErr_SetString(ThreadError, "thread already started"); + return -1; + } + self->state = THREAD_HANDLE_STARTING; + PyMutex_Unlock(&self->mutex); + + // Do all the heavy lifting outside of the mutex. All other operations on + // the handle should fail since the handle is in the starting state. + + // gh-109795: Use PyMem_RawMalloc() instead of PyMem_Malloc(), + // because it should be possible to call thread_bootstate_free() + // without holding the GIL. + struct bootstate *boot = PyMem_RawMalloc(sizeof(struct bootstate)); + if (boot == NULL) { + PyErr_NoMemory(); + goto start_failed; + } + PyInterpreterState *interp = _PyInterpreterState_GET(); + boot->tstate = _PyThreadState_New(interp, _PyThreadState_WHENCE_THREADING); + if (boot->tstate == NULL) { + PyMem_RawFree(boot); + if (!PyErr_Occurred()) { + PyErr_NoMemory(); + } + goto start_failed; + } + boot->func = Py_NewRef(func); + boot->args = Py_NewRef(args); + boot->kwargs = Py_XNewRef(kwargs); + boot->handle = self; + ThreadHandle_incref(self); + boot->handle_ready = (PyEvent){0}; + + PyThread_ident_t ident; + PyThread_handle_t os_handle; + if (PyThread_start_joinable_thread(thread_run, boot, &ident, &os_handle)) { + PyThreadState_Clear(boot->tstate); + PyThreadState_Delete(boot->tstate); + thread_bootstate_free(boot, 1); + PyErr_SetString(ThreadError, "can't start new thread"); + goto start_failed; + } + + // Mark the handle running + PyMutex_Lock(&self->mutex); + assert(self->state == THREAD_HANDLE_STARTING); + self->ident = ident; + self->has_os_handle = 1; + self->os_handle = os_handle; + self->state = THREAD_HANDLE_RUNNING; + PyMutex_Unlock(&self->mutex); + + // Unblock the thread + _PyEvent_Notify(&boot->handle_ready); + + return 0; + +start_failed: + _PyOnceFlag_CallOnce(&self->once, (_Py_once_fn_t *)force_done, self); + return -1; +} + +static int +join_thread(void *arg) +{ + ThreadHandle *handle = (ThreadHandle*)arg; + assert(get_thread_handle_state(handle) == THREAD_HANDLE_RUNNING); + PyThread_handle_t os_handle; + if (ThreadHandle_get_os_handle(handle, &os_handle)) { + int err = 0; + Py_BEGIN_ALLOW_THREADS + err = PyThread_join_thread(os_handle); + Py_END_ALLOW_THREADS + if (err) { + PyErr_SetString(ThreadError, "Failed joining thread"); + return -1; + } + } + set_thread_handle_state(handle, THREAD_HANDLE_DONE); + return 0; +} + +static int +check_started(ThreadHandle *self) +{ + ThreadHandleState state = get_thread_handle_state(self); + if (state < THREAD_HANDLE_RUNNING) { + PyErr_SetString(ThreadError, "thread not started"); + return -1; + } + return 0; +} + +static int +ThreadHandle_join(ThreadHandle *self, PyTime_t timeout_ns) +{ + if (check_started(self) < 0) { + return -1; + } + + // We want to perform this check outside of the `_PyOnceFlag` to prevent + // deadlock in the scenario where another thread joins us and we then + // attempt to join ourselves. However, it's not safe to check thread + // identity once the handle's os thread has finished. We may end up reusing + // the identity stored in the handle and erroneously think we are + // attempting to join ourselves. + // + // To work around this, we set `thread_is_exiting` immediately before + // `thread_run` returns. We can be sure that we are not attempting to join + // ourselves if the handle's thread is about to exit. + if (!_PyEvent_IsSet(&self->thread_is_exiting) && + ThreadHandle_ident(self) == PyThread_get_thread_ident_ex()) { + // PyThread_join_thread() would deadlock or error out. + PyErr_SetString(ThreadError, "Cannot join current thread"); + return -1; + } + + // Wait until the deadline for the thread to exit. + PyTime_t deadline = timeout_ns != -1 ? _PyDeadline_Init(timeout_ns) : 0; + int detach = 1; + while (!PyEvent_WaitTimed(&self->thread_is_exiting, timeout_ns, detach)) { + if (deadline) { + // _PyDeadline_Get will return a negative value if the deadline has + // been exceeded. + timeout_ns = Py_MAX(_PyDeadline_Get(deadline), 0); + } + + if (timeout_ns) { + // Interrupted + if (Py_MakePendingCalls() < 0) { + return -1; + } + } + else { + // Timed out + return 0; + } + } + + if (_PyOnceFlag_CallOnce(&self->once, join_thread, self) == -1) { + return -1; + } + assert(get_thread_handle_state(self) == THREAD_HANDLE_DONE); + return 0; +} + +static int +set_done(ThreadHandle *handle) +{ + assert(get_thread_handle_state(handle) == THREAD_HANDLE_RUNNING); + if (detach_thread(handle) < 0) { + PyErr_SetString(ThreadError, "failed detaching handle"); + return -1; + } + _PyEvent_Notify(&handle->thread_is_exiting); + set_thread_handle_state(handle, THREAD_HANDLE_DONE); + return 0; +} + +static int +ThreadHandle_set_done(ThreadHandle *self) +{ + if (check_started(self) < 0) { + return -1; + } + + if (_PyOnceFlag_CallOnce(&self->once, (_Py_once_fn_t *)set_done, self) == + -1) { + return -1; + } + assert(get_thread_handle_state(self) == THREAD_HANDLE_DONE); + return 0; +} + +// A wrapper around a ThreadHandle. typedef struct { PyObject_HEAD - PyThread_type_lock lock_lock; - PyObject *in_weakreflist; - char locked; /* for sanity checking */ -} lockobject; + + ThreadHandle *handle; +} PyThreadHandleObject; + +static PyThreadHandleObject * +PyThreadHandleObject_new(PyTypeObject *type) +{ + ThreadHandle *handle = ThreadHandle_new(); + if (handle == NULL) { + return NULL; + } + + PyThreadHandleObject *self = + (PyThreadHandleObject *)type->tp_alloc(type, 0); + if (self == NULL) { + ThreadHandle_decref(handle); + return NULL; + } + + self->handle = handle; + + return self; +} + +static PyObject * +PyThreadHandleObject_tp_new(PyTypeObject *type, PyObject *args, PyObject *kwds) +{ + return (PyObject *)PyThreadHandleObject_new(type); +} static int -lock_traverse(lockobject *self, visitproc visit, void *arg) +PyThreadHandleObject_traverse(PyThreadHandleObject *self, visitproc visit, + void *arg) { Py_VISIT(Py_TYPE(self)); return 0; } static void -lock_dealloc(lockobject *self) +PyThreadHandleObject_dealloc(PyThreadHandleObject *self) { PyObject_GC_UnTrack(self); - if (self->in_weakreflist != NULL) { - PyObject_ClearWeakRefs((PyObject *) self); - } - if (self->lock_lock != NULL) { - /* Unlock the lock so it's safe to free it */ - if (self->locked) - PyThread_release_lock(self->lock_lock); - PyThread_free_lock(self->lock_lock); - } PyTypeObject *tp = Py_TYPE(self); - tp->tp_free((PyObject*)self); + ThreadHandle_decref(self->handle); + tp->tp_free(self); Py_DECREF(tp); } -/* Helper to acquire an interruptible lock with a timeout. If the lock acquire - * is interrupted, signal handlers are run, and if they raise an exception, - * PY_LOCK_INTR is returned. Otherwise, PY_LOCK_ACQUIRED or PY_LOCK_FAILURE - * are returned, depending on whether the lock can be acquired within the - * timeout. - */ -static PyLockStatus -acquire_timed(PyThread_type_lock lock, _PyTime_t timeout) +static PyObject * +PyThreadHandleObject_repr(PyThreadHandleObject *self) { - PyThreadState *tstate = _PyThreadState_GET(); - _PyTime_t endtime = 0; - if (timeout > 0) { - endtime = _PyDeadline_Init(timeout); + PyThread_ident_t ident = ThreadHandle_ident(self->handle); + return PyUnicode_FromFormat("<%s object: ident=%" PY_FORMAT_THREAD_IDENT_T ">", + Py_TYPE(self)->tp_name, ident); +} + +static PyObject * +PyThreadHandleObject_get_ident(PyThreadHandleObject *self, + PyObject *Py_UNUSED(ignored)) +{ + return PyLong_FromUnsignedLongLong(ThreadHandle_ident(self->handle)); +} + +static PyObject * +PyThreadHandleObject_join(PyThreadHandleObject *self, PyObject *args) +{ + PyObject *timeout_obj = NULL; + if (!PyArg_ParseTuple(args, "|O:join", &timeout_obj)) { + return NULL; + } + + PyTime_t timeout_ns = -1; + if (timeout_obj != NULL && timeout_obj != Py_None) { + if (_PyTime_FromSecondsObject(&timeout_ns, timeout_obj, + _PyTime_ROUND_TIMEOUT) < 0) { + return NULL; + } } - PyLockStatus r; - do { - _PyTime_t microseconds; - microseconds = _PyTime_AsMicroseconds(timeout, _PyTime_ROUND_CEILING); + if (ThreadHandle_join(self->handle, timeout_ns) < 0) { + return NULL; + } + Py_RETURN_NONE; +} - /* first a simple non-blocking try without releasing the GIL */ - r = PyThread_acquire_lock_timed(lock, 0, 0); - if (r == PY_LOCK_FAILURE && microseconds != 0) { - Py_BEGIN_ALLOW_THREADS - r = PyThread_acquire_lock_timed(lock, microseconds, 1); - Py_END_ALLOW_THREADS +static PyObject * +PyThreadHandleObject_is_done(PyThreadHandleObject *self, + PyObject *Py_UNUSED(ignored)) +{ + if (_PyEvent_IsSet(&self->handle->thread_is_exiting)) { + if (_PyOnceFlag_CallOnce(&self->handle->once, join_thread, self->handle) == -1) { + return NULL; } + Py_RETURN_TRUE; + } + else { + Py_RETURN_FALSE; + } +} - if (r == PY_LOCK_INTR) { - /* Run signal handlers if we were interrupted. Propagate - * exceptions from signal handlers, such as KeyboardInterrupt, by - * passing up PY_LOCK_INTR. */ - if (_PyEval_MakePendingCalls(tstate) < 0) { - return PY_LOCK_INTR; - } +static PyObject * +PyThreadHandleObject_set_done(PyThreadHandleObject *self, + PyObject *Py_UNUSED(ignored)) +{ + if (ThreadHandle_set_done(self->handle) < 0) { + return NULL; + } + Py_RETURN_NONE; +} - /* If we're using a timeout, recompute the timeout after processing - * signals, since those can take time. */ - if (timeout > 0) { - timeout = _PyDeadline_Get(endtime); +static PyGetSetDef ThreadHandle_getsetlist[] = { + {"ident", (getter)PyThreadHandleObject_get_ident, NULL, NULL}, + {0}, +}; - /* Check for negative values, since those mean block forever. - */ - if (timeout < 0) { - r = PY_LOCK_FAILURE; - } - } - } - } while (r == PY_LOCK_INTR); /* Retry if we were interrupted. */ +static PyMethodDef ThreadHandle_methods[] = { + {"join", (PyCFunction)PyThreadHandleObject_join, METH_VARARGS, NULL}, + {"_set_done", (PyCFunction)PyThreadHandleObject_set_done, METH_NOARGS, NULL}, + {"is_done", (PyCFunction)PyThreadHandleObject_is_done, METH_NOARGS, NULL}, + {0, 0} +}; + +static PyType_Slot ThreadHandle_Type_slots[] = { + {Py_tp_dealloc, (destructor)PyThreadHandleObject_dealloc}, + {Py_tp_repr, (reprfunc)PyThreadHandleObject_repr}, + {Py_tp_getset, ThreadHandle_getsetlist}, + {Py_tp_traverse, PyThreadHandleObject_traverse}, + {Py_tp_methods, ThreadHandle_methods}, + {Py_tp_new, PyThreadHandleObject_tp_new}, + {0, 0} +}; + +static PyType_Spec ThreadHandle_Type_spec = { + "_thread._ThreadHandle", + sizeof(PyThreadHandleObject), + 0, + Py_TPFLAGS_DEFAULT | Py_TPFLAGS_IMMUTABLETYPE | Py_TPFLAGS_HAVE_GC, + ThreadHandle_Type_slots, +}; + +/* Lock objects */ + +typedef struct { + PyObject_HEAD + PyMutex lock; +} lockobject; + +static int +lock_traverse(lockobject *self, visitproc visit, void *arg) +{ + Py_VISIT(Py_TYPE(self)); + return 0; +} + +static void +lock_dealloc(lockobject *self) +{ + PyObject_GC_UnTrack(self); + PyObject_ClearWeakRefs((PyObject *) self); + PyTypeObject *tp = Py_TYPE(self); + tp->tp_free((PyObject*)self); + Py_DECREF(tp); +} - return r; +static inline PyLockStatus +acquire_timed(PyThread_type_lock lock, PyTime_t timeout) +{ + return PyThread_acquire_lock_timed_with_retries(lock, timeout); } static int lock_acquire_parse_args(PyObject *args, PyObject *kwds, - _PyTime_t *timeout) + PyTime_t *timeout) { char *kwlist[] = {"blocking", "timeout", NULL}; int blocking = 1; PyObject *timeout_obj = NULL; - const _PyTime_t unset_timeout = _PyTime_FromSeconds(-1); - - *timeout = unset_timeout ; - if (!PyArg_ParseTupleAndKeywords(args, kwds, "|pO:acquire", kwlist, &blocking, &timeout_obj)) return -1; + // XXX Use PyThread_ParseTimeoutArg(). + + const PyTime_t unset_timeout = _PyTime_FromSeconds(-1); + *timeout = unset_timeout; + if (timeout_obj && _PyTime_FromSecondsObject(timeout, timeout_obj, _PyTime_ROUND_TIMEOUT) < 0) @@ -152,13 +765,13 @@ lock_acquire_parse_args(PyObject *args, PyObject *kwds, } if (*timeout < 0 && *timeout != unset_timeout) { PyErr_SetString(PyExc_ValueError, - "timeout value must be positive"); + "timeout value must be a non-negative number"); return -1; } if (!blocking) *timeout = 0; else if (*timeout != unset_timeout) { - _PyTime_t microseconds; + PyTime_t microseconds; microseconds = _PyTime_AsMicroseconds(*timeout, _PyTime_ROUND_TIMEOUT); if (microseconds > PY_TIMEOUT_MAX) { @@ -173,23 +786,22 @@ lock_acquire_parse_args(PyObject *args, PyObject *kwds, static PyObject * lock_PyThread_acquire_lock(lockobject *self, PyObject *args, PyObject *kwds) { - _PyTime_t timeout; + PyTime_t timeout; if (lock_acquire_parse_args(args, kwds, &timeout) < 0) return NULL; - PyLockStatus r = acquire_timed(self->lock_lock, timeout); + PyLockStatus r = _PyMutex_LockTimed(&self->lock, timeout, + _PY_LOCK_HANDLE_SIGNALS | _PY_LOCK_DETACH); if (r == PY_LOCK_INTR) { return NULL; } - if (r == PY_LOCK_ACQUIRED) - self->locked = 1; return PyBool_FromLong(r == PY_LOCK_ACQUIRED); } PyDoc_STRVAR(acquire_doc, -"acquire(blocking=True, timeout=-1) -> bool\n\ -(acquire_lock() is an obsolete synonym)\n\ +"acquire($self, /, blocking=True, timeout=-1)\n\ +--\n\ \n\ Lock the lock. Without argument, this blocks if the lock is already\n\ locked (even by the same thread), waiting for another thread to release\n\ @@ -198,80 +810,123 @@ With an argument, this will only block if the argument is true,\n\ and the return value reflects whether the lock is acquired.\n\ The blocking operation is interruptible."); +PyDoc_STRVAR(acquire_lock_doc, +"acquire_lock($self, /, blocking=True, timeout=-1)\n\ +--\n\ +\n\ +An obsolete synonym of acquire()."); + +PyDoc_STRVAR(enter_doc, +"__enter__($self, /)\n\ +--\n\ +\n\ +Lock the lock."); + static PyObject * lock_PyThread_release_lock(lockobject *self, PyObject *Py_UNUSED(ignored)) { /* Sanity check: the lock must be locked */ - if (!self->locked) { + if (_PyMutex_TryUnlock(&self->lock) < 0) { PyErr_SetString(ThreadError, "release unlocked lock"); return NULL; } - PyThread_release_lock(self->lock_lock); - self->locked = 0; Py_RETURN_NONE; } PyDoc_STRVAR(release_doc, -"release()\n\ -(release_lock() is an obsolete synonym)\n\ +"release($self, /)\n\ +--\n\ \n\ Release the lock, allowing another thread that is blocked waiting for\n\ the lock to acquire the lock. The lock must be in the locked state,\n\ but it needn't be locked by the same thread that unlocks it."); +PyDoc_STRVAR(release_lock_doc, +"release_lock($self, /)\n\ +--\n\ +\n\ +An obsolete synonym of release()."); + +PyDoc_STRVAR(lock_exit_doc, +"__exit__($self, /, *exc_info)\n\ +--\n\ +\n\ +Release the lock."); + static PyObject * lock_locked_lock(lockobject *self, PyObject *Py_UNUSED(ignored)) { - return PyBool_FromLong((long)self->locked); + return PyBool_FromLong(PyMutex_IsLocked(&self->lock)); } PyDoc_STRVAR(locked_doc, -"locked() -> bool\n\ -(locked_lock() is an obsolete synonym)\n\ +"locked($self, /)\n\ +--\n\ \n\ Return whether the lock is in the locked state."); +PyDoc_STRVAR(locked_lock_doc, +"locked_lock($self, /)\n\ +--\n\ +\n\ +An obsolete synonym of locked()."); + static PyObject * lock_repr(lockobject *self) { return PyUnicode_FromFormat("<%s %s object at %p>", - self->locked ? "locked" : "unlocked", Py_TYPE(self)->tp_name, self); + PyMutex_IsLocked(&self->lock) ? "locked" : "unlocked", Py_TYPE(self)->tp_name, self); } #ifdef HAVE_FORK static PyObject * lock__at_fork_reinit(lockobject *self, PyObject *Py_UNUSED(args)) { - if (_PyThread_at_fork_reinit(&self->lock_lock) < 0) { - PyErr_SetString(ThreadError, "failed to reinitialize lock at fork"); - return NULL; + _PyMutex_at_fork_reinit(&self->lock); + Py_RETURN_NONE; +} +#endif /* HAVE_FORK */ + +static lockobject *newlockobject(PyObject *module); + +static PyObject * +lock_new(PyTypeObject *type, PyObject *args, PyObject *kwargs) +{ + // convert to AC? + if (!_PyArg_NoKeywords("lock", kwargs)) { + goto error; + } + if (!_PyArg_CheckPositional("lock", PyTuple_GET_SIZE(args), 0, 0)) { + goto error; } - self->locked = 0; + PyObject *module = PyType_GetModuleByDef(type, &thread_module); + assert(module != NULL); + return (PyObject *)newlockobject(module); - Py_RETURN_NONE; +error: + return NULL; } -#endif /* HAVE_FORK */ static PyMethodDef lock_methods[] = { {"acquire_lock", _PyCFunction_CAST(lock_PyThread_acquire_lock), - METH_VARARGS | METH_KEYWORDS, acquire_doc}, + METH_VARARGS | METH_KEYWORDS, acquire_lock_doc}, {"acquire", _PyCFunction_CAST(lock_PyThread_acquire_lock), METH_VARARGS | METH_KEYWORDS, acquire_doc}, {"release_lock", (PyCFunction)lock_PyThread_release_lock, - METH_NOARGS, release_doc}, + METH_NOARGS, release_lock_doc}, {"release", (PyCFunction)lock_PyThread_release_lock, METH_NOARGS, release_doc}, {"locked_lock", (PyCFunction)lock_locked_lock, - METH_NOARGS, locked_doc}, + METH_NOARGS, locked_lock_doc}, {"locked", (PyCFunction)lock_locked_lock, METH_NOARGS, locked_doc}, {"__enter__", _PyCFunction_CAST(lock_PyThread_acquire_lock), - METH_VARARGS | METH_KEYWORDS, acquire_doc}, + METH_VARARGS | METH_KEYWORDS, enter_doc}, {"__exit__", (PyCFunction)lock_PyThread_release_lock, - METH_VARARGS, release_doc}, + METH_VARARGS, lock_exit_doc}, #ifdef HAVE_FORK {"_at_fork_reinit", (PyCFunction)lock__at_fork_reinit, METH_NOARGS, NULL}, @@ -280,7 +935,10 @@ static PyMethodDef lock_methods[] = { }; PyDoc_STRVAR(lock_doc, -"A lock object is a synchronization primitive. To create a lock,\n\ +"lock()\n\ +--\n\ +\n\ +A lock object is a synchronization primitive. To create a lock,\n\ call threading.Lock(). Methods are:\n\ \n\ acquire() -- lock the lock, possibly blocking until it can be obtained\n\ @@ -291,18 +949,13 @@ A lock is not owned by the thread that locked it; another thread may\n\ unlock it. A thread attempting to lock a lock that it has already locked\n\ will block until another thread unlocks it. Deadlocks may ensue."); -static PyMemberDef lock_type_members[] = { - {"__weaklistoffset__", T_PYSSIZET, offsetof(lockobject, in_weakreflist), READONLY}, - {NULL}, -}; - static PyType_Slot lock_type_slots[] = { {Py_tp_dealloc, (destructor)lock_dealloc}, {Py_tp_repr, (reprfunc)lock_repr}, {Py_tp_doc, (void *)lock_doc}, {Py_tp_methods, lock_methods}, {Py_tp_traverse, lock_traverse}, - {Py_tp_members, lock_type_members}, + {Py_tp_new, lock_new}, {0, 0} }; @@ -310,7 +963,7 @@ static PyType_Spec lock_type_spec = { .name = "_thread.lock", .basicsize = sizeof(lockobject), .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | - Py_TPFLAGS_DISALLOW_INSTANTIATION | Py_TPFLAGS_IMMUTABLETYPE), + Py_TPFLAGS_IMMUTABLETYPE | Py_TPFLAGS_MANAGED_WEAKREF), .slots = lock_type_slots, }; @@ -319,7 +972,7 @@ static PyType_Spec lock_type_spec = { typedef struct { PyObject_HEAD PyThread_type_lock rlock_lock; - unsigned long rlock_owner; + PyThread_ident_t rlock_owner; unsigned long rlock_count; PyObject *in_weakreflist; } rlockobject; @@ -352,18 +1005,26 @@ rlock_dealloc(rlockobject *self) Py_DECREF(tp); } +static bool +rlock_is_owned_by(rlockobject *self, PyThread_ident_t tid) +{ + PyThread_ident_t owner_tid = + _Py_atomic_load_ullong_relaxed(&self->rlock_owner); + return owner_tid == tid && self->rlock_count > 0; +} + static PyObject * rlock_acquire(rlockobject *self, PyObject *args, PyObject *kwds) { - _PyTime_t timeout; - unsigned long tid; + PyTime_t timeout; + PyThread_ident_t tid; PyLockStatus r = PY_LOCK_ACQUIRED; if (lock_acquire_parse_args(args, kwds, &timeout) < 0) return NULL; - tid = PyThread_get_thread_ident(); - if (self->rlock_count > 0 && tid == self->rlock_owner) { + tid = PyThread_get_thread_ident_ex(); + if (rlock_is_owned_by(self, tid)) { unsigned long count = self->rlock_count + 1; if (count <= self->rlock_count) { PyErr_SetString(PyExc_OverflowError, @@ -376,7 +1037,7 @@ rlock_acquire(rlockobject *self, PyObject *args, PyObject *kwds) r = acquire_timed(self->rlock_lock, timeout); if (r == PY_LOCK_ACQUIRED) { assert(self->rlock_count == 0); - self->rlock_owner = tid; + _Py_atomic_store_ullong_relaxed(&self->rlock_owner, tid); self->rlock_count = 1; } else if (r == PY_LOCK_INTR) { @@ -387,7 +1048,8 @@ rlock_acquire(rlockobject *self, PyObject *args, PyObject *kwds) } PyDoc_STRVAR(rlock_acquire_doc, -"acquire(blocking=True) -> bool\n\ +"acquire($self, /, blocking=True, timeout=-1)\n\ +--\n\ \n\ Lock the lock. `blocking` indicates whether we should wait\n\ for the lock to be available or not. If `blocking` is False\n\ @@ -402,25 +1064,32 @@ Precisely, if the current thread already holds the lock, its\n\ internal counter is simply incremented. If nobody holds the lock,\n\ the lock is taken and its internal counter initialized to 1."); +PyDoc_STRVAR(rlock_enter_doc, +"__enter__($self, /)\n\ +--\n\ +\n\ +Lock the lock."); + static PyObject * rlock_release(rlockobject *self, PyObject *Py_UNUSED(ignored)) { - unsigned long tid = PyThread_get_thread_ident(); + PyThread_ident_t tid = PyThread_get_thread_ident_ex(); - if (self->rlock_count == 0 || self->rlock_owner != tid) { + if (!rlock_is_owned_by(self, tid)) { PyErr_SetString(PyExc_RuntimeError, "cannot release un-acquired lock"); return NULL; } if (--self->rlock_count == 0) { - self->rlock_owner = 0; + _Py_atomic_store_ullong_relaxed(&self->rlock_owner, 0); PyThread_release_lock(self->rlock_lock); } Py_RETURN_NONE; } PyDoc_STRVAR(rlock_release_doc, -"release()\n\ +"release($self, /)\n\ +--\n\ \n\ Release the lock, allowing another thread that is blocked waiting for\n\ the lock to acquire the lock. The lock must be in the locked state,\n\ @@ -431,14 +1100,21 @@ Do note that if the lock was acquire()d several times in a row by the\n\ current thread, release() needs to be called as many times for the lock\n\ to be available for other threads."); +PyDoc_STRVAR(rlock_exit_doc, +"__exit__($self, /, *exc_info)\n\ +--\n\ +\n\ +Release the lock."); + static PyObject * rlock_acquire_restore(rlockobject *self, PyObject *args) { - unsigned long owner; + PyThread_ident_t owner; unsigned long count; int r = 1; - if (!PyArg_ParseTuple(args, "(kk):_acquire_restore", &count, &owner)) + if (!PyArg_ParseTuple(args, "(k" Py_PARSE_THREAD_IDENT_T "):_acquire_restore", + &count, &owner)) return NULL; if (!PyThread_acquire_lock(self->rlock_lock, 0)) { @@ -451,20 +1127,21 @@ rlock_acquire_restore(rlockobject *self, PyObject *args) return NULL; } assert(self->rlock_count == 0); - self->rlock_owner = owner; + _Py_atomic_store_ullong_relaxed(&self->rlock_owner, owner); self->rlock_count = count; Py_RETURN_NONE; } PyDoc_STRVAR(rlock_acquire_restore_doc, -"_acquire_restore(state) -> None\n\ +"_acquire_restore($self, state, /)\n\ +--\n\ \n\ For internal use by `threading.Condition`."); static PyObject * rlock_release_save(rlockobject *self, PyObject *Py_UNUSED(ignored)) { - unsigned long owner; + PyThread_ident_t owner; unsigned long count; if (self->rlock_count == 0) { @@ -476,42 +1153,46 @@ rlock_release_save(rlockobject *self, PyObject *Py_UNUSED(ignored)) owner = self->rlock_owner; count = self->rlock_count; self->rlock_count = 0; - self->rlock_owner = 0; + _Py_atomic_store_ullong_relaxed(&self->rlock_owner, 0); PyThread_release_lock(self->rlock_lock); - return Py_BuildValue("kk", count, owner); + return Py_BuildValue("k" Py_PARSE_THREAD_IDENT_T, count, owner); } PyDoc_STRVAR(rlock_release_save_doc, -"_release_save() -> tuple\n\ +"_release_save($self, /)\n\ +--\n\ \n\ For internal use by `threading.Condition`."); static PyObject * rlock_recursion_count(rlockobject *self, PyObject *Py_UNUSED(ignored)) { - unsigned long tid = PyThread_get_thread_ident(); - return PyLong_FromUnsignedLong( - self->rlock_owner == tid ? self->rlock_count : 0UL); + PyThread_ident_t tid = PyThread_get_thread_ident_ex(); + PyThread_ident_t owner = + _Py_atomic_load_ullong_relaxed(&self->rlock_owner); + return PyLong_FromUnsignedLong(owner == tid ? self->rlock_count : 0UL); } PyDoc_STRVAR(rlock_recursion_count_doc, -"_recursion_count() -> int\n\ +"_recursion_count($self, /)\n\ +--\n\ \n\ For internal use by reentrancy checks."); static PyObject * rlock_is_owned(rlockobject *self, PyObject *Py_UNUSED(ignored)) { - unsigned long tid = PyThread_get_thread_ident(); + PyThread_ident_t tid = PyThread_get_thread_ident_ex(); - if (self->rlock_count > 0 && self->rlock_owner == tid) { + if (rlock_is_owned_by(self, tid)) { Py_RETURN_TRUE; } Py_RETURN_FALSE; } PyDoc_STRVAR(rlock_is_owned_doc, -"_is_owned() -> bool\n\ +"_is_owned($self, /)\n\ +--\n\ \n\ For internal use by `threading.Condition`."); @@ -538,9 +1219,12 @@ rlock_new(PyTypeObject *type, PyObject *args, PyObject *kwds) static PyObject * rlock_repr(rlockobject *self) { - return PyUnicode_FromFormat("<%s %s object owner=%ld count=%lu at %p>", + PyThread_ident_t owner = + _Py_atomic_load_ullong_relaxed(&self->rlock_owner); + return PyUnicode_FromFormat( + "<%s %s object owner=%" PY_FORMAT_THREAD_IDENT_T " count=%lu at %p>", self->rlock_count ? "locked" : "unlocked", - Py_TYPE(self)->tp_name, self->rlock_owner, + Py_TYPE(self)->tp_name, owner, self->rlock_count, self); } @@ -576,9 +1260,9 @@ static PyMethodDef rlock_methods[] = { {"_recursion_count", (PyCFunction)rlock_recursion_count, METH_NOARGS, rlock_recursion_count_doc}, {"__enter__", _PyCFunction_CAST(rlock_acquire), - METH_VARARGS | METH_KEYWORDS, rlock_acquire_doc}, + METH_VARARGS | METH_KEYWORDS, rlock_enter_doc}, {"__exit__", (PyCFunction)rlock_release, - METH_VARARGS, rlock_release_doc}, + METH_VARARGS, rlock_exit_doc}, #ifdef HAVE_FORK {"_at_fork_reinit", (PyCFunction)rlock__at_fork_reinit, METH_NOARGS, NULL}, @@ -588,7 +1272,7 @@ static PyMethodDef rlock_methods[] = { static PyMemberDef rlock_type_members[] = { - {"__weaklistoffset__", T_PYSSIZET, offsetof(rlockobject, in_weakreflist), READONLY}, + {"__weaklistoffset__", Py_T_PYSSIZET, offsetof(rlockobject, in_weakreflist), Py_READONLY}, {NULL}, }; @@ -621,16 +1305,7 @@ newlockobject(PyObject *module) if (self == NULL) { return NULL; } - - self->lock_lock = PyThread_allocate_lock(); - self->locked = 0; - self->in_weakreflist = NULL; - - if (self->lock_lock == NULL) { - Py_DECREF(self); - PyErr_SetString(ThreadError, "can't allocate lock"); - return NULL; - } + self->lock = (PyMutex){0}; return self; } @@ -651,48 +1326,58 @@ newlockobject(PyObject *module) Our implementation uses small "localdummy" objects in order to break the reference chain. These trivial objects are hashable (using the default scheme of identity hashing) and weakrefable. - Each thread-state holds a separate localdummy for each local object - (as a /strong reference/), - and each thread-local object holds a dict mapping /weak references/ - of localdummies to local dicts. + + Each thread-state holds two separate localdummy objects: + + - `threading_local_key` is used as a key to retrieve the locals dictionary + for the thread in any `threading.local` object. + - `threading_local_sentinel` is used to signal when a thread is being + destroyed. Consequently, the associated thread-state must hold the only + reference. + + Each `threading.local` object contains a dict mapping localdummy keys to + locals dicts and a set containing weak references to localdummy + sentinels. Each sentinel weak reference has a callback that removes itself + and the locals dict for the key from the `threading.local` object when + called. Therefore: - - only the thread-state dict holds a strong reference to the dummies - - only the thread-local object holds a strong reference to the local dicts - - only outside objects (application- or library-level) hold strong - references to the thread-local objects - - as soon as a thread-state dict is destroyed, the weakref callbacks of all - dummies attached to that thread are called, and destroy the corresponding - local dicts from thread-local objects - - as soon as a thread-local object is destroyed, its local dicts are - destroyed and its dummies are manually removed from all thread states - - the GC can do its work correctly when a thread-local object is dangling, - without any interference from the thread-state dicts + - The thread-state only holds strong references to localdummy objects, which + cannot participate in cycles. + - Only outside objects (application- or library-level) hold strong + references to the thread-local objects. + - As soon as thread-state's sentinel dummy is destroyed the callbacks for + all weakrefs attached to the sentinel are called, and destroy the + corresponding local dicts from thread-local objects. + - As soon as a thread-local object is destroyed, its local dicts are + destroyed. + - The GC can do its work correctly when a thread-local object is dangling, + without any interference from the thread-state dicts. - As an additional optimization, each localdummy holds a borrowed reference - to the corresponding localdict. This borrowed reference is only used - by the thread-local object which has created the localdummy, which should - guarantee that the localdict still exists when accessed. + This dual key arrangement is necessary to ensure that `threading.local` + values can be retrieved from finalizers. If we were to only keep a mapping + of localdummy weakrefs to locals dicts it's possible that the weakrefs would + be cleared before finalizers were called (GC currently clears weakrefs that + are garbage before invoking finalizers), causing lookups in finalizers to + fail. */ typedef struct { PyObject_HEAD - PyObject *localdict; /* Borrowed reference! */ PyObject *weakreflist; /* List of weak references to self */ } localdummyobject; static void localdummy_dealloc(localdummyobject *self) { - if (self->weakreflist != NULL) - PyObject_ClearWeakRefs((PyObject *) self); + FT_CLEAR_WEAKREFS((PyObject *) self, self->weakreflist); PyTypeObject *tp = Py_TYPE(self); tp->tp_free((PyObject*)self); Py_DECREF(tp); } static PyMemberDef local_dummy_type_members[] = { - {"__weaklistoffset__", T_PYSSIZET, offsetof(localdummyobject, weakreflist), READONLY}, + {"__weaklistoffset__", Py_T_PYSSIZET, offsetof(localdummyobject, weakreflist), Py_READONLY}, {NULL}, }; @@ -714,80 +1399,60 @@ static PyType_Spec local_dummy_type_spec = { typedef struct { PyObject_HEAD - PyObject *key; PyObject *args; PyObject *kw; PyObject *weakreflist; /* List of weak references to self */ - /* A {localdummy weakref -> localdict} dict */ - PyObject *dummies; - /* The callback for weakrefs to localdummies */ - PyObject *wr_callback; + /* A {localdummy -> localdict} dict */ + PyObject *localdicts; + /* A set of weakrefs to thread sentinels localdummies*/ + PyObject *thread_watchdogs; } localobject; /* Forward declaration */ -static PyObject *_ldict(localobject *self, thread_module_state *state); -static PyObject *_localdummy_destroyed(PyObject *meth_self, PyObject *dummyweakref); +static int create_localsdict(localobject *self, thread_module_state *state, + PyObject **localsdict, PyObject **sentinel_wr); +static PyObject *clear_locals(PyObject *meth_self, PyObject *dummyweakref); -/* Create and register the dummy for the current thread. - Returns a borrowed reference of the corresponding local dict */ +/* Create a weakref to the sentinel localdummy for the current thread */ static PyObject * -_local_create_dummy(localobject *self, thread_module_state *state) +create_sentinel_wr(localobject *self) { - PyObject *ldict = NULL, *wr = NULL; - localdummyobject *dummy = NULL; - PyTypeObject *type = state->local_dummy_type; + static PyMethodDef wr_callback_def = { + "clear_locals", (PyCFunction) clear_locals, METH_O + }; - PyObject *tdict = PyThreadState_GetDict(); - if (tdict == NULL) { - PyErr_SetString(PyExc_SystemError, - "Couldn't get thread-state dictionary"); - goto err; - } + PyThreadState *tstate = PyThreadState_Get(); - ldict = PyDict_New(); - if (ldict == NULL) { - goto err; - } - dummy = (localdummyobject *) type->tp_alloc(type, 0); - if (dummy == NULL) { - goto err; - } - dummy->localdict = ldict; - wr = PyWeakref_NewRef((PyObject *) dummy, self->wr_callback); - if (wr == NULL) { - goto err; + /* We use a weak reference to self in the callback closure + in order to avoid spurious reference cycles */ + PyObject *self_wr = PyWeakref_NewRef((PyObject *) self, NULL); + if (self_wr == NULL) { + return NULL; } - /* As a side-effect, this will cache the weakref's hash before the - dummy gets deleted */ - int r = PyDict_SetItem(self->dummies, wr, ldict); - if (r < 0) { - goto err; + PyObject *args = PyTuple_New(2); + if (args == NULL) { + Py_DECREF(self_wr); + return NULL; } - Py_CLEAR(wr); - r = PyDict_SetItem(tdict, self->key, (PyObject *) dummy); - if (r < 0) { - goto err; + PyTuple_SET_ITEM(args, 0, self_wr); + PyTuple_SET_ITEM(args, 1, Py_NewRef(tstate->threading_local_key)); + + PyObject *cb = PyCFunction_New(&wr_callback_def, args); + Py_DECREF(args); + if (cb == NULL) { + return NULL; } - Py_CLEAR(dummy); - Py_DECREF(ldict); - return ldict; + PyObject *wr = PyWeakref_NewRef(tstate->threading_local_sentinel, cb); + Py_DECREF(cb); -err: - Py_XDECREF(ldict); - Py_XDECREF(wr); - Py_XDECREF(dummy); - return NULL; + return wr; } static PyObject * local_new(PyTypeObject *type, PyObject *args, PyObject *kw) { - static PyMethodDef wr_callback_def = { - "_localdummy_destroyed", (PyCFunction) _localdummy_destroyed, METH_O - }; - if (type->tp_init == PyBaseObject_Type.tp_init) { int rc = 0; if (args != NULL) @@ -804,6 +1469,7 @@ local_new(PyTypeObject *type, PyObject *args, PyObject *kw) } PyObject *module = PyType_GetModuleByDef(type, &thread_module); + assert(module != NULL); thread_module_state *state = get_thread_state(module); localobject *self = (localobject *)type->tp_alloc(type, 0); @@ -813,30 +1479,25 @@ local_new(PyTypeObject *type, PyObject *args, PyObject *kw) self->args = Py_XNewRef(args); self->kw = Py_XNewRef(kw); - self->key = PyUnicode_FromFormat("thread.local.%p", self); - if (self->key == NULL) { - goto err; - } - self->dummies = PyDict_New(); - if (self->dummies == NULL) { + self->localdicts = PyDict_New(); + if (self->localdicts == NULL) { goto err; } - /* We use a weak reference to self in the callback closure - in order to avoid spurious reference cycles */ - PyObject *wr = PyWeakref_NewRef((PyObject *) self, NULL); - if (wr == NULL) { + self->thread_watchdogs = PySet_New(NULL); + if (self->thread_watchdogs == NULL) { goto err; } - self->wr_callback = PyCFunction_NewEx(&wr_callback_def, wr, NULL); - Py_DECREF(wr); - if (self->wr_callback == NULL) { - goto err; - } - if (_local_create_dummy(self, state) == NULL) { + + PyObject *localsdict = NULL; + PyObject *sentinel_wr = NULL; + if (create_localsdict(self, state, &localsdict, &sentinel_wr) < 0) { goto err; } + Py_DECREF(localsdict); + Py_DECREF(sentinel_wr); + return (PyObject *)self; err: @@ -850,7 +1511,8 @@ local_traverse(localobject *self, visitproc visit, void *arg) Py_VISIT(Py_TYPE(self)); Py_VISIT(self->args); Py_VISIT(self->kw); - Py_VISIT(self->dummies); + Py_VISIT(self->localdicts); + Py_VISIT(self->thread_watchdogs); return 0; } @@ -859,30 +1521,8 @@ local_clear(localobject *self) { Py_CLEAR(self->args); Py_CLEAR(self->kw); - Py_CLEAR(self->dummies); - Py_CLEAR(self->wr_callback); - /* Remove all strong references to dummies from the thread states */ - if (self->key) { - PyInterpreterState *interp = _PyInterpreterState_GET(); - _PyRuntimeState *runtime = &_PyRuntime; - HEAD_LOCK(runtime); - PyThreadState *tstate = PyInterpreterState_ThreadHead(interp); - HEAD_UNLOCK(runtime); - while (tstate) { - if (tstate->dict) { - PyObject *v = _PyDict_Pop(tstate->dict, self->key, Py_None); - if (v != NULL) { - Py_DECREF(v); - } - else { - PyErr_Clear(); - } - } - HEAD_LOCK(runtime); - tstate = PyThreadState_Next(tstate); - HEAD_UNLOCK(runtime); - } - } + Py_CLEAR(self->localdicts); + Py_CLEAR(self->thread_watchdogs); return 0; } @@ -898,48 +1538,142 @@ local_dealloc(localobject *self) PyObject_GC_UnTrack(self); local_clear(self); - Py_XDECREF(self->key); PyTypeObject *tp = Py_TYPE(self); tp->tp_free((PyObject*)self); Py_DECREF(tp); } -/* Returns a borrowed reference to the local dict, creating it if necessary */ +/* Create the TLS key and sentinel if they don't exist */ +static int +create_localdummies(thread_module_state *state) +{ + PyThreadState *tstate = _PyThreadState_GET(); + + if (tstate->threading_local_key != NULL) { + return 0; + } + + PyTypeObject *ld_type = state->local_dummy_type; + tstate->threading_local_key = ld_type->tp_alloc(ld_type, 0); + if (tstate->threading_local_key == NULL) { + return -1; + } + + tstate->threading_local_sentinel = ld_type->tp_alloc(ld_type, 0); + if (tstate->threading_local_sentinel == NULL) { + Py_CLEAR(tstate->threading_local_key); + return -1; + } + + return 0; +} + +/* Insert a localsdict and sentinel weakref for the current thread, placing + strong references in localsdict and sentinel_wr, respectively. +*/ +static int +create_localsdict(localobject *self, thread_module_state *state, + PyObject **localsdict, PyObject **sentinel_wr) +{ + PyThreadState *tstate = _PyThreadState_GET(); + PyObject *ldict = NULL; + PyObject *wr = NULL; + + if (create_localdummies(state) < 0) { + goto err; + } + + /* Create and insert the locals dict and sentinel weakref */ + ldict = PyDict_New(); + if (ldict == NULL) { + goto err; + } + + if (PyDict_SetItem(self->localdicts, tstate->threading_local_key, ldict) < + 0) { + goto err; + } + + wr = create_sentinel_wr(self); + if (wr == NULL) { + PyObject *exc = PyErr_GetRaisedException(); + if (PyDict_DelItem(self->localdicts, tstate->threading_local_key) < + 0) { + PyErr_WriteUnraisable((PyObject *)self); + } + PyErr_SetRaisedException(exc); + goto err; + } + + if (PySet_Add(self->thread_watchdogs, wr) < 0) { + PyObject *exc = PyErr_GetRaisedException(); + if (PyDict_DelItem(self->localdicts, tstate->threading_local_key) < + 0) { + PyErr_WriteUnraisable((PyObject *)self); + } + PyErr_SetRaisedException(exc); + goto err; + } + + *localsdict = ldict; + *sentinel_wr = wr; + return 0; + +err: + Py_XDECREF(ldict); + Py_XDECREF(wr); + return -1; +} + +/* Return a strong reference to the locals dict for the current thread, + creating it if necessary. +*/ static PyObject * _ldict(localobject *self, thread_module_state *state) { - PyObject *tdict = PyThreadState_GetDict(); - if (tdict == NULL) { - PyErr_SetString(PyExc_SystemError, - "Couldn't get thread-state dictionary"); + if (create_localdummies(state) < 0) { return NULL; } + /* Check if a localsdict already exists */ PyObject *ldict; - PyObject *dummy = PyDict_GetItemWithError(tdict, self->key); - if (dummy == NULL) { - if (PyErr_Occurred()) { - return NULL; - } - ldict = _local_create_dummy(self, state); - if (ldict == NULL) - return NULL; + PyThreadState *tstate = _PyThreadState_GET(); + if (PyDict_GetItemRef(self->localdicts, tstate->threading_local_key, + &ldict) < 0) { + return NULL; + } + if (ldict != NULL) { + return ldict; + } - if (Py_TYPE(self)->tp_init != PyBaseObject_Type.tp_init && - Py_TYPE(self)->tp_init((PyObject*)self, - self->args, self->kw) < 0) { - /* we need to get rid of ldict from thread so - we create a new one the next time we do an attr - access */ - PyDict_DelItem(tdict, self->key); - return NULL; - } + /* threading.local hasn't been instantiated for this thread */ + PyObject *wr; + if (create_localsdict(self, state, &ldict, &wr) < 0) { + return NULL; } - else { - assert(Py_IS_TYPE(dummy, state->local_dummy_type)); - ldict = ((localdummyobject *) dummy)->localdict; + + /* run __init__ if we're a subtype of `threading.local` */ + if (Py_TYPE(self)->tp_init != PyBaseObject_Type.tp_init && + Py_TYPE(self)->tp_init((PyObject *)self, self->args, self->kw) < 0) { + /* we need to get rid of ldict from thread so + we create a new one the next time we do an attr + access */ + PyObject *exc = PyErr_GetRaisedException(); + if (PyDict_DelItem(self->localdicts, tstate->threading_local_key) < + 0) { + PyErr_WriteUnraisable((PyObject *)self); + PyErr_Clear(); + } + if (PySet_Discard(self->thread_watchdogs, wr) < 0) { + PyErr_WriteUnraisable((PyObject *)self); + } + PyErr_SetRaisedException(exc); + Py_DECREF(ldict); + Py_DECREF(wr); + return NULL; } + Py_DECREF(wr); return ldict; } @@ -948,31 +1682,39 @@ static int local_setattro(localobject *self, PyObject *name, PyObject *v) { PyObject *module = PyType_GetModuleByDef(Py_TYPE(self), &thread_module); + assert(module != NULL); thread_module_state *state = get_thread_state(module); PyObject *ldict = _ldict(self, state); if (ldict == NULL) { - return -1; + goto err; } int r = PyObject_RichCompareBool(name, &_Py_ID(__dict__), Py_EQ); if (r == -1) { - return -1; + goto err; } if (r == 1) { PyErr_Format(PyExc_AttributeError, "'%.100s' object attribute %R is read-only", Py_TYPE(self)->tp_name, name); - return -1; + goto err; } - return _PyObject_GenericSetAttrWithDict((PyObject *)self, name, v, ldict); + int st = + _PyObject_GenericSetAttrWithDict((PyObject *)self, name, v, ldict); + Py_DECREF(ldict); + return st; + +err: + Py_XDECREF(ldict); + return -1; } static PyObject *local_getattro(localobject *, PyObject *); static PyMemberDef local_type_members[] = { - {"__weaklistoffset__", T_PYSSIZET, offsetof(localobject, weakreflist), READONLY}, + {"__weaklistoffset__", Py_T_PYSSIZET, offsetof(localobject, weakreflist), Py_READONLY}, {NULL}, }; @@ -980,7 +1722,7 @@ static PyType_Slot local_type_slots[] = { {Py_tp_dealloc, (destructor)local_dealloc}, {Py_tp_getattro, (getattrofunc)local_getattro}, {Py_tp_setattro, (setattrofunc)local_setattro}, - {Py_tp_doc, "Thread-local data"}, + {Py_tp_doc, "_local()\n--\n\nThread-local data"}, {Py_tp_traverse, (traverseproc)local_traverse}, {Py_tp_clear, (inquiry)local_clear}, {Py_tp_new, local_new}, @@ -1000,6 +1742,7 @@ static PyObject * local_getattro(localobject *self, PyObject *name) { PyObject *module = PyType_GetModuleByDef(Py_TYPE(self), &thread_module); + assert(module != NULL); thread_module_state *state = get_thread_state(module); PyObject *ldict = _ldict(self, state); @@ -1008,139 +1751,71 @@ local_getattro(localobject *self, PyObject *name) int r = PyObject_RichCompareBool(name, &_Py_ID(__dict__), Py_EQ); if (r == 1) { - return Py_NewRef(ldict); + return ldict; } if (r == -1) { + Py_DECREF(ldict); return NULL; } if (!Py_IS_TYPE(self, state->local_type)) { /* use generic lookup for subtypes */ - return _PyObject_GenericGetAttrWithDict((PyObject *)self, name, - ldict, 0); + PyObject *res = + _PyObject_GenericGetAttrWithDict((PyObject *)self, name, ldict, 0); + Py_DECREF(ldict); + return res; } /* Optimization: just look in dict ourselves */ - PyObject *value = PyDict_GetItemWithError(ldict, name); - if (value != NULL) { - return Py_NewRef(value); - } - if (PyErr_Occurred()) { - return NULL; + PyObject *value; + if (PyDict_GetItemRef(ldict, name, &value) != 0) { + // found or error + Py_DECREF(ldict); + return value; } /* Fall back on generic to get __class__ and __dict__ */ - return _PyObject_GenericGetAttrWithDict( - (PyObject *)self, name, ldict, 0); + PyObject *res = + _PyObject_GenericGetAttrWithDict((PyObject *)self, name, ldict, 0); + Py_DECREF(ldict); + return res; } -/* Called when a dummy is destroyed. */ +/* Called when a dummy is destroyed, indicating that the owning thread is being + * cleared. */ static PyObject * -_localdummy_destroyed(PyObject *localweakref, PyObject *dummyweakref) +clear_locals(PyObject *locals_and_key, PyObject *dummyweakref) { - assert(PyWeakref_CheckRef(localweakref)); - PyObject *obj = PyWeakref_GET_OBJECT(localweakref); - if (obj == Py_None) { + PyObject *localweakref = PyTuple_GetItem(locals_and_key, 0); + localobject *self = (localobject *)_PyWeakref_GET_REF(localweakref); + if (self == NULL) { Py_RETURN_NONE; } /* If the thread-local object is still alive and not being cleared, remove the corresponding local dict */ - localobject *self = (localobject *)Py_NewRef(obj); - if (self->dummies != NULL) { - PyObject *ldict; - ldict = PyDict_GetItemWithError(self->dummies, dummyweakref); - if (ldict != NULL) { - PyDict_DelItem(self->dummies, dummyweakref); + if (self->localdicts != NULL) { + PyObject *key = PyTuple_GetItem(locals_and_key, 1); + if (PyDict_Pop(self->localdicts, key, NULL) < 0) { + PyErr_WriteUnraisable((PyObject*)self); } - if (PyErr_Occurred()) - PyErr_WriteUnraisable(obj); } - Py_DECREF(obj); - Py_RETURN_NONE; -} - -/* Module functions */ - -struct bootstate { - PyThreadState *tstate; - PyObject *func; - PyObject *args; - PyObject *kwargs; -}; - - -static void -thread_bootstate_free(struct bootstate *boot, int decref) -{ - if (decref) { - Py_DECREF(boot->func); - Py_DECREF(boot->args); - Py_XDECREF(boot->kwargs); - } - PyMem_RawFree(boot); -} - - -static void -thread_run(void *boot_raw) -{ - struct bootstate *boot = (struct bootstate *) boot_raw; - PyThreadState *tstate = boot->tstate; - - // gh-108987: If _thread.start_new_thread() is called before or while - // Python is being finalized, thread_run() can called *after*. - // _PyRuntimeState_SetFinalizing() is called. At this point, all Python - // threads must exit, except of the thread calling Py_Finalize() whch holds - // the GIL and must not exit. - // - // At this stage, tstate can be a dangling pointer (point to freed memory), - // it's ok to call _PyThreadState_MustExit() with a dangling pointer. - if (_PyThreadState_MustExit(tstate)) { - // Don't call PyThreadState_Clear() nor _PyThreadState_DeleteCurrent(). - // These functions are called on tstate indirectly by Py_Finalize() - // which calls _PyInterpreterState_Clear(). - // - // Py_DECREF() cannot be called because the GIL is not held: leak - // references on purpose. Python is being finalized anyway. - thread_bootstate_free(boot, 0); - goto exit; - } - - _PyThreadState_Bind(tstate); - PyEval_AcquireThread(tstate); - tstate->interp->threads.count++; - - PyObject *res = PyObject_Call(boot->func, boot->args, boot->kwargs); - if (res == NULL) { - if (PyErr_ExceptionMatches(PyExc_SystemExit)) - /* SystemExit is ignored silently */ - PyErr_Clear(); - else { - _PyErr_WriteUnraisableMsg("in thread started by", boot->func); + if (self->thread_watchdogs != NULL) { + if (PySet_Discard(self->thread_watchdogs, dummyweakref) < 0) { + PyErr_WriteUnraisable((PyObject *)self); } } - else { - Py_DECREF(res); - } - thread_bootstate_free(boot, 1); - - tstate->interp->threads.count--; - PyThreadState_Clear(tstate); - _PyThreadState_DeleteCurrent(tstate); - -exit: - // bpo-44434: Don't call explicitly PyThread_exit_thread(). On Linux with - // the glibc, pthread_exit() can abort the whole process if dlopen() fails - // to open the libgcc_s.so library (ex: EMFILE error). - return; + Py_DECREF(self); + Py_RETURN_NONE; } +/* Module functions */ + static PyObject * thread_daemon_threads_allowed(PyObject *module, PyObject *Py_UNUSED(ignored)) { - PyInterpreterState *interp = _PyInterpreterState_Get(); + PyInterpreterState *interp = _PyInterpreterState_GET(); if (interp->feature_flags & Py_RTFLAGS_DAEMON_THREADS) { Py_RETURN_TRUE; } @@ -1150,15 +1825,50 @@ thread_daemon_threads_allowed(PyObject *module, PyObject *Py_UNUSED(ignored)) } PyDoc_STRVAR(daemon_threads_allowed_doc, -"daemon_threads_allowed()\n\ +"daemon_threads_allowed($module, /)\n\ +--\n\ \n\ Return True if daemon threads are allowed in the current interpreter,\n\ and False otherwise.\n"); +static int +do_start_new_thread(thread_module_state *state, PyObject *func, PyObject *args, + PyObject *kwargs, ThreadHandle *handle, int daemon) +{ + PyInterpreterState *interp = _PyInterpreterState_GET(); + if (!_PyInterpreterState_HasFeature(interp, Py_RTFLAGS_THREADS)) { + PyErr_SetString(PyExc_RuntimeError, + "thread is not supported for isolated subinterpreters"); + return -1; + } + if (_PyInterpreterState_GetFinalizing(interp) != NULL) { + PyErr_SetString(PyExc_PythonFinalizationError, + "can't create new thread at interpreter shutdown"); + return -1; + } + + if (!daemon) { + // Add the handle before starting the thread to avoid adding a handle + // to a thread that has already finished (i.e. if the thread finishes + // before the call to `ThreadHandle_start()` below returns). + add_to_shutdown_handles(state, handle); + } + + if (ThreadHandle_start(handle, func, args, kwargs) < 0) { + if (!daemon) { + remove_from_shutdown_handles(handle); + } + return -1; + } + + return 0; +} + static PyObject * -thread_PyThread_start_new_thread(PyObject *self, PyObject *fargs) +thread_PyThread_start_new_thread(PyObject *module, PyObject *fargs) { PyObject *func, *args, *kwargs = NULL; + thread_module_state *state = get_thread_state(module); if (!PyArg_UnpackTuple(fargs, "start_new_thread", 2, 3, &func, &args, &kwargs)) @@ -1184,58 +1894,112 @@ thread_PyThread_start_new_thread(PyObject *self, PyObject *fargs) return NULL; } - PyInterpreterState *interp = _PyInterpreterState_GET(); - if (!_PyInterpreterState_HasFeature(interp, Py_RTFLAGS_THREADS)) { - PyErr_SetString(PyExc_RuntimeError, - "thread is not supported for isolated subinterpreters"); + ThreadHandle *handle = ThreadHandle_new(); + if (handle == NULL) { return NULL; } - if (_PyInterpreterState_GetFinalizing(interp) != NULL) { - PyErr_SetString(PyExc_RuntimeError, - "can't create new thread at interpreter shutdown"); + + int st = + do_start_new_thread(state, func, args, kwargs, handle, /*daemon=*/1); + if (st < 0) { + ThreadHandle_decref(handle); return NULL; } + PyThread_ident_t ident = ThreadHandle_ident(handle); + ThreadHandle_decref(handle); + return PyLong_FromUnsignedLongLong(ident); +} - // gh-109795: Use PyMem_RawMalloc() instead of PyMem_Malloc(), - // because it should be possible to call thread_bootstate_free() - // without holding the GIL. - struct bootstate *boot = PyMem_RawMalloc(sizeof(struct bootstate)); - if (boot == NULL) { - return PyErr_NoMemory(); +PyDoc_STRVAR(start_new_thread_doc, +"start_new_thread($module, function, args, kwargs={}, /)\n\ +--\n\ +\n\ +Start a new thread and return its identifier.\n\ +\n\ +The thread will call the function with positional arguments from the\n\ +tuple args and keyword arguments taken from the optional dictionary\n\ +kwargs. The thread exits when the function returns; the return value\n\ +is ignored. The thread will also exit when the function raises an\n\ +unhandled exception; a stack trace will be printed unless the exception\n\ +is SystemExit."); + +PyDoc_STRVAR(start_new_doc, +"start_new($module, function, args, kwargs={}, /)\n\ +--\n\ +\n\ +An obsolete synonym of start_new_thread()."); + +static PyObject * +thread_PyThread_start_joinable_thread(PyObject *module, PyObject *fargs, + PyObject *fkwargs) +{ + static char *keywords[] = {"function", "handle", "daemon", NULL}; + PyObject *func = NULL; + int daemon = 1; + thread_module_state *state = get_thread_state(module); + PyObject *hobj = NULL; + if (!PyArg_ParseTupleAndKeywords(fargs, fkwargs, + "O|Op:start_joinable_thread", keywords, + &func, &hobj, &daemon)) { + return NULL; } - boot->tstate = _PyThreadState_New(interp); - if (boot->tstate == NULL) { - PyMem_RawFree(boot); - if (!PyErr_Occurred()) { - return PyErr_NoMemory(); - } + + if (!PyCallable_Check(func)) { + PyErr_SetString(PyExc_TypeError, + "thread function must be callable"); return NULL; } - boot->func = Py_NewRef(func); - boot->args = Py_NewRef(args); - boot->kwargs = Py_XNewRef(kwargs); - unsigned long ident = PyThread_start_new_thread(thread_run, (void*) boot); - if (ident == PYTHREAD_INVALID_THREAD_ID) { - PyErr_SetString(ThreadError, "can't start new thread"); - PyThreadState_Clear(boot->tstate); - PyThreadState_Delete(boot->tstate); - thread_bootstate_free(boot, 1); + if (hobj == NULL) { + hobj = Py_None; + } + else if (hobj != Py_None && !Py_IS_TYPE(hobj, state->thread_handle_type)) { + PyErr_SetString(PyExc_TypeError, "'handle' must be a _ThreadHandle"); + return NULL; + } + + if (PySys_Audit("_thread.start_joinable_thread", "OiO", func, daemon, + hobj) < 0) { + return NULL; + } + + if (hobj == Py_None) { + hobj = (PyObject *)PyThreadHandleObject_new(state->thread_handle_type); + if (hobj == NULL) { + return NULL; + } + } + else { + Py_INCREF(hobj); + } + + PyObject* args = PyTuple_New(0); + if (args == NULL) { return NULL; } - return PyLong_FromUnsignedLong(ident); + int st = do_start_new_thread(state, func, args, + /*kwargs=*/ NULL, ((PyThreadHandleObject*)hobj)->handle, daemon); + Py_DECREF(args); + if (st < 0) { + Py_DECREF(hobj); + return NULL; + } + return (PyObject *) hobj; } -PyDoc_STRVAR(start_new_doc, -"start_new_thread(function, args[, kwargs])\n\ -(start_new() is an obsolete synonym)\n\ +PyDoc_STRVAR(start_joinable_doc, +"start_joinable_thread($module, /, function, handle=None, daemon=True)\n\ +--\n\ \n\ -Start a new thread and return its identifier. The thread will call the\n\ -function with positional arguments from the tuple args and keyword arguments\n\ -taken from the optional dictionary kwargs. The thread exits when the\n\ -function returns; the return value is ignored. The thread will also exit\n\ -when the function raises an unhandled exception; a stack trace will be\n\ -printed unless the exception is SystemExit.\n"); +*For internal use only*: start a new thread.\n\ +\n\ +Like start_new_thread(), this starts a new thread calling the given function.\n\ +Unlike start_new_thread(), this returns a handle object with methods to join\n\ +or detach the given thread.\n\ +This function is not for third-party code, please use the\n\ +`threading` module instead. During finalization the runtime will not wait for\n\ +the thread to exit if daemon is True. If handle is provided it must be a\n\ +newly created thread._ThreadHandle instance."); static PyObject * thread_PyThread_exit_thread(PyObject *self, PyObject *Py_UNUSED(ignored)) @@ -1245,12 +2009,18 @@ thread_PyThread_exit_thread(PyObject *self, PyObject *Py_UNUSED(ignored)) } PyDoc_STRVAR(exit_doc, -"exit()\n\ -(exit_thread() is an obsolete synonym)\n\ +"exit($module, /)\n\ +--\n\ \n\ This is synonymous to ``raise SystemExit''. It will cause the current\n\ thread to exit silently unless the exception is caught."); +PyDoc_STRVAR(exit_thread_doc, +"exit_thread($module, /)\n\ +--\n\ +\n\ +An obsolete synonym of exit()."); + static PyObject * thread_PyThread_interrupt_main(PyObject *self, PyObject *args) { @@ -1267,7 +2037,8 @@ thread_PyThread_interrupt_main(PyObject *self, PyObject *args) } PyDoc_STRVAR(interrupt_doc, -"interrupt_main(signum=signal.SIGINT, /)\n\ +"interrupt_main($module, signum=signal.SIGINT, /)\n\ +--\n\ \n\ Simulate the arrival of the given signal in the main thread,\n\ where the corresponding signal handler will be executed.\n\ @@ -1277,34 +2048,39 @@ A subthread can use this function to interrupt the main thread.\n\ Note: the default signal handler for SIGINT raises ``KeyboardInterrupt``." ); -static lockobject *newlockobject(PyObject *module); - static PyObject * thread_PyThread_allocate_lock(PyObject *module, PyObject *Py_UNUSED(ignored)) { return (PyObject *) newlockobject(module); } -PyDoc_STRVAR(allocate_doc, -"allocate_lock() -> lock object\n\ -(allocate() is an obsolete synonym)\n\ +PyDoc_STRVAR(allocate_lock_doc, +"allocate_lock($module, /)\n\ +--\n\ \n\ Create a new lock object. See help(type(threading.Lock())) for\n\ information about locks."); +PyDoc_STRVAR(allocate_doc, +"allocate($module, /)\n\ +--\n\ +\n\ +An obsolete synonym of allocate_lock()."); + static PyObject * thread_get_ident(PyObject *self, PyObject *Py_UNUSED(ignored)) { - unsigned long ident = PyThread_get_thread_ident(); + PyThread_ident_t ident = PyThread_get_thread_ident_ex(); if (ident == PYTHREAD_INVALID_THREAD_ID) { PyErr_SetString(ThreadError, "no current thread ident"); return NULL; } - return PyLong_FromUnsignedLong(ident); + return PyLong_FromUnsignedLongLong(ident); } PyDoc_STRVAR(get_ident_doc, -"get_ident() -> integer\n\ +"get_ident($module, /)\n\ +--\n\ \n\ Return a non-zero integer that uniquely identifies the current thread\n\ amongst other threads that exist simultaneously.\n\ @@ -1323,7 +2099,8 @@ thread_get_native_id(PyObject *self, PyObject *Py_UNUSED(ignored)) } PyDoc_STRVAR(get_native_id_doc, -"get_native_id() -> integer\n\ +"get_native_id($module, /)\n\ +--\n\ \n\ Return a non-negative integer identifying the thread as reported\n\ by the OS (kernel). This may be used to uniquely identify a\n\ @@ -1334,13 +2111,13 @@ static PyObject * thread__count(PyObject *self, PyObject *Py_UNUSED(ignored)) { PyInterpreterState *interp = _PyInterpreterState_GET(); - return PyLong_FromLong(interp->threads.count); + return PyLong_FromSsize_t(_Py_atomic_load_ssize(&interp->threads.count)); } PyDoc_STRVAR(_count_doc, -"_count() -> integer\n\ +"_count($module, /)\n\ +--\n\ \n\ -\ Return the number of currently running Python threads, excluding\n\ the main thread. The returned number comprises all threads created\n\ through `start_new_thread()` as well as `threading.Thread`, and not\n\ @@ -1349,66 +2126,6 @@ yet finished.\n\ This function is meant for internal and specialized purposes only.\n\ In most applications `threading.enumerate()` should be used instead."); -static void -release_sentinel(void *wr_raw) -{ - PyObject *wr = _PyObject_CAST(wr_raw); - /* Tricky: this function is called when the current thread state - is being deleted. Therefore, only simple C code can safely - execute here. */ - PyObject *obj = PyWeakref_GET_OBJECT(wr); - lockobject *lock; - if (obj != Py_None) { - lock = (lockobject *) obj; - if (lock->locked) { - PyThread_release_lock(lock->lock_lock); - lock->locked = 0; - } - } - /* Deallocating a weakref with a NULL callback only calls - PyObject_GC_Del(), which can't call any Python code. */ - Py_DECREF(wr); -} - -static PyObject * -thread__set_sentinel(PyObject *module, PyObject *Py_UNUSED(ignored)) -{ - PyObject *wr; - PyThreadState *tstate = _PyThreadState_GET(); - lockobject *lock; - - if (tstate->on_delete_data != NULL) { - /* We must support the re-creation of the lock from a - fork()ed child. */ - assert(tstate->on_delete == &release_sentinel); - wr = (PyObject *) tstate->on_delete_data; - tstate->on_delete = NULL; - tstate->on_delete_data = NULL; - Py_DECREF(wr); - } - lock = newlockobject(module); - if (lock == NULL) - return NULL; - /* The lock is owned by whoever called _set_sentinel(), but the weakref - hangs to the thread state. */ - wr = PyWeakref_NewRef((PyObject *) lock, NULL); - if (wr == NULL) { - Py_DECREF(lock); - return NULL; - } - tstate->on_delete_data = (void *) wr; - tstate->on_delete = &release_sentinel; - return (PyObject *) lock; -} - -PyDoc_STRVAR(_set_sentinel_doc, -"_set_sentinel() -> lock\n\ -\n\ -Set a sentinel lock that will be released when the current thread\n\ -state is finalized (after it is untied from the interpreter).\n\ -\n\ -This is a private API for the threading module."); - static PyObject * thread_stack_size(PyObject *self, PyObject *args) { @@ -1444,7 +2161,8 @@ thread_stack_size(PyObject *self, PyObject *args) } PyDoc_STRVAR(stack_size_doc, -"stack_size([size]) -> size\n\ +"stack_size($module, size=0, /)\n\ +--\n\ \n\ Return the thread stack size used when creating new threads. The\n\ optional size argument specifies the stack size (in bytes) to be used\n\ @@ -1474,7 +2192,7 @@ thread_excepthook_file(PyObject *file, PyObject *exc_type, PyObject *exc_value, PyObject *name = NULL; if (thread != Py_None) { - if (_PyObject_LookupAttr(thread, &_Py_ID(name), &name) < 0) { + if (PyObject_GetOptionalAttr(thread, &_Py_ID(name), &name) < 0) { return -1; } } @@ -1486,8 +2204,8 @@ thread_excepthook_file(PyObject *file, PyObject *exc_type, PyObject *exc_value, Py_DECREF(name); } else { - unsigned long ident = PyThread_get_thread_ident(); - PyObject *str = PyUnicode_FromFormat("%lu", ident); + PyThread_ident_t ident = PyThread_get_thread_ident_ex(); + PyObject *str = PyUnicode_FromFormat("%" PY_FORMAT_THREAD_IDENT_T, ident); if (str != NULL) { if (PyFile_WriteObject(str, file, Py_PRINT_RAW) < 0) { Py_DECREF(str); @@ -1512,11 +2230,9 @@ thread_excepthook_file(PyObject *file, PyObject *exc_type, PyObject *exc_value, _PyErr_Display(file, exc_type, exc_value, exc_traceback); /* Call file.flush() */ - PyObject *res = PyObject_CallMethodNoArgs(file, &_Py_ID(flush)); - if (!res) { + if (_PyFile_Flush(file) < 0) { return -1; } - Py_DECREF(res); return 0; } @@ -1567,9 +2283,12 @@ thread_excepthook(PyObject *module, PyObject *args) PyObject *exc_tb = PyStructSequence_GET_ITEM(args, 2); PyObject *thread = PyStructSequence_GET_ITEM(args, 3); - PyThreadState *tstate = _PyThreadState_GET(); - PyObject *file = _PySys_GetAttr(tstate, &_Py_ID(stderr)); + PyObject *file; + if (_PySys_GetOptionalAttr( &_Py_ID(stderr), &file) < 0) { + return NULL; + } if (file == NULL || file == Py_None) { + Py_XDECREF(file); if (thread == Py_None) { /* do nothing if sys.stderr is None and thread is None */ Py_RETURN_NONE; @@ -1586,9 +2305,6 @@ thread_excepthook(PyObject *module, PyObject *args) Py_RETURN_NONE; } } - else { - Py_INCREF(file); - } int res = thread_excepthook_file(file, exc_type, exc_value, exc_tb, thread); @@ -1601,7 +2317,8 @@ thread_excepthook(PyObject *module, PyObject *args) } PyDoc_STRVAR(excepthook_doc, -"excepthook(exc_type, exc_value, exc_traceback, thread)\n\ +"_excepthook($module, args, /)\n\ +--\n\ \n\ Handle uncaught Thread.run() exception."); @@ -1613,23 +2330,117 @@ thread__is_main_interpreter(PyObject *module, PyObject *Py_UNUSED(ignored)) } PyDoc_STRVAR(thread__is_main_interpreter_doc, -"_is_main_interpreter()\n\ +"_is_main_interpreter($module, /)\n\ +--\n\ \n\ Return True if the current interpreter is the main Python interpreter."); +static PyObject * +thread_shutdown(PyObject *self, PyObject *args) +{ + PyThread_ident_t ident = PyThread_get_thread_ident_ex(); + thread_module_state *state = get_thread_state(self); + + for (;;) { + ThreadHandle *handle = NULL; + + // Find a thread that's not yet finished. + HEAD_LOCK(&_PyRuntime); + struct llist_node *node; + llist_for_each_safe(node, &state->shutdown_handles) { + ThreadHandle *cur = llist_data(node, ThreadHandle, shutdown_node); + if (cur->ident != ident) { + ThreadHandle_incref(cur); + handle = cur; + break; + } + } + HEAD_UNLOCK(&_PyRuntime); + + if (!handle) { + // No more threads to wait on! + break; + } + + // Wait for the thread to finish. If we're interrupted, such + // as by a ctrl-c we print the error and exit early. + if (ThreadHandle_join(handle, -1) < 0) { + PyErr_WriteUnraisable(NULL); + ThreadHandle_decref(handle); + Py_RETURN_NONE; + } + + ThreadHandle_decref(handle); + } + + Py_RETURN_NONE; +} + +PyDoc_STRVAR(shutdown_doc, +"_shutdown($module, /)\n\ +--\n\ +\n\ +Wait for all non-daemon threads (other than the calling thread) to stop."); + +static PyObject * +thread__make_thread_handle(PyObject *module, PyObject *identobj) +{ + thread_module_state *state = get_thread_state(module); + if (!PyLong_Check(identobj)) { + PyErr_SetString(PyExc_TypeError, "ident must be an integer"); + return NULL; + } + PyThread_ident_t ident = PyLong_AsUnsignedLongLong(identobj); + if (PyErr_Occurred()) { + return NULL; + } + PyThreadHandleObject *hobj = + PyThreadHandleObject_new(state->thread_handle_type); + if (hobj == NULL) { + return NULL; + } + PyMutex_Lock(&hobj->handle->mutex); + hobj->handle->ident = ident; + hobj->handle->state = THREAD_HANDLE_RUNNING; + PyMutex_Unlock(&hobj->handle->mutex); + return (PyObject*) hobj; +} + +PyDoc_STRVAR(thread__make_thread_handle_doc, +"_make_thread_handle($module, ident, /)\n\ +--\n\ +\n\ +Internal only. Make a thread handle for threads not spawned\n\ +by the _thread or threading module."); + +static PyObject * +thread__get_main_thread_ident(PyObject *module, PyObject *Py_UNUSED(ignored)) +{ + return PyLong_FromUnsignedLongLong(_PyRuntime.main_thread); +} + +PyDoc_STRVAR(thread__get_main_thread_ident_doc, +"_get_main_thread_ident($module, /)\n\ +--\n\ +\n\ +Internal only. Return a non-zero integer that uniquely identifies the main thread\n\ +of the main interpreter."); + static PyMethodDef thread_methods[] = { {"start_new_thread", (PyCFunction)thread_PyThread_start_new_thread, - METH_VARARGS, start_new_doc}, + METH_VARARGS, start_new_thread_doc}, {"start_new", (PyCFunction)thread_PyThread_start_new_thread, METH_VARARGS, start_new_doc}, + {"start_joinable_thread", _PyCFunction_CAST(thread_PyThread_start_joinable_thread), + METH_VARARGS | METH_KEYWORDS, start_joinable_doc}, {"daemon_threads_allowed", (PyCFunction)thread_daemon_threads_allowed, METH_NOARGS, daemon_threads_allowed_doc}, {"allocate_lock", thread_PyThread_allocate_lock, - METH_NOARGS, allocate_doc}, + METH_NOARGS, allocate_lock_doc}, {"allocate", thread_PyThread_allocate_lock, METH_NOARGS, allocate_doc}, {"exit_thread", thread_PyThread_exit_thread, - METH_NOARGS, exit_doc}, + METH_NOARGS, exit_thread_doc}, {"exit", thread_PyThread_exit_thread, METH_NOARGS, exit_doc}, {"interrupt_main", (PyCFunction)thread_PyThread_interrupt_main, @@ -1644,12 +2455,16 @@ static PyMethodDef thread_methods[] = { METH_NOARGS, _count_doc}, {"stack_size", (PyCFunction)thread_stack_size, METH_VARARGS, stack_size_doc}, - {"_set_sentinel", thread__set_sentinel, - METH_NOARGS, _set_sentinel_doc}, {"_excepthook", thread_excepthook, METH_O, excepthook_doc}, {"_is_main_interpreter", thread__is_main_interpreter, METH_NOARGS, thread__is_main_interpreter_doc}, + {"_shutdown", thread_shutdown, + METH_NOARGS, shutdown_doc}, + {"_make_thread_handle", thread__make_thread_handle, + METH_O, thread__make_thread_handle_doc}, + {"_get_main_thread_ident", thread__get_main_thread_ident, + METH_NOARGS, thread__get_main_thread_ident_doc}, {NULL, NULL} /* sentinel */ }; @@ -1665,11 +2480,24 @@ thread_module_exec(PyObject *module) // Initialize the C thread library PyThread_init_thread(); + // _ThreadHandle + state->thread_handle_type = (PyTypeObject *)PyType_FromSpec(&ThreadHandle_Type_spec); + if (state->thread_handle_type == NULL) { + return -1; + } + if (PyDict_SetItemString(d, "_ThreadHandle", (PyObject *)state->thread_handle_type) < 0) { + return -1; + } + // Lock - state->lock_type = (PyTypeObject *)PyType_FromSpec(&lock_type_spec); + state->lock_type = (PyTypeObject *)PyType_FromModuleAndSpec(module, &lock_type_spec, NULL); if (state->lock_type == NULL) { return -1; } + if (PyModule_AddType(module, state->lock_type) < 0) { + return -1; + } + // Old alias: lock -> LockType if (PyDict_SetItemString(d, "LockType", (PyObject *)state->lock_type) < 0) { return -1; } @@ -1716,16 +2544,18 @@ thread_module_exec(PyObject *module) // TIMEOUT_MAX double timeout_max = (double)PY_TIMEOUT_MAX * 1e-6; - double time_max = _PyTime_AsSecondsDouble(_PyTime_MAX); + double time_max = PyTime_AsSecondsDouble(PyTime_MAX); timeout_max = Py_MIN(timeout_max, time_max); // Round towards minus infinity timeout_max = floor(timeout_max); - if (_PyModule_Add(module, "TIMEOUT_MAX", + if (PyModule_Add(module, "TIMEOUT_MAX", PyFloat_FromDouble(timeout_max)) < 0) { return -1; } + llist_init(&state->shutdown_handles); + return 0; } @@ -1738,6 +2568,7 @@ thread_module_traverse(PyObject *module, visitproc visit, void *arg) Py_VISIT(state->lock_type); Py_VISIT(state->local_type); Py_VISIT(state->local_dummy_type); + Py_VISIT(state->thread_handle_type); return 0; } @@ -1749,6 +2580,11 @@ thread_module_clear(PyObject *module) Py_CLEAR(state->lock_type); Py_CLEAR(state->local_type); Py_CLEAR(state->local_dummy_type); + Py_CLEAR(state->thread_handle_type); + // Remove any remaining handles (e.g. if shutdown exited early due to + // interrupt) so that attempts to unlink the handle after our module state + // is destroyed do not crash. + clear_shutdown_handles(state); return 0; } @@ -1767,6 +2603,7 @@ The 'threading' module provides a more convenient interface."); static PyModuleDef_Slot thread_module_slots[] = { {Py_mod_exec, thread_module_exec}, {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED}, + {Py_mod_gil, Py_MOD_GIL_NOT_USED}, {0, NULL} }; |