# _thread — API bas niveau de gestion de fils d'exécution¶

This module provides low-level primitives for working with multiple threads (also called light-weight processes or tasks) --- multiple threads of control sharing their global data space. For synchronization, simple locks (also called mutexes or binary semaphores) are provided. The threading module provides an easier to use and higher-level threading API built on top of this module.

Modifié dans la version 3.7: This module used to be optional, it is now always available.

Ce module définit les constantes et fonctions suivantes :

exception _thread.error

Levée lors d'erreur spécifique aux fils d'exécution.

Modifié dans la version 3.3: Ceci est à présent un synonyme de l'exception native RuntimeError.

_thread.LockType

C'est le type des verrous.

_thread.start_new_thread(function, args[, kwargs])

Start a new thread and return its identifier. The thread executes the function function with the argument list args (which must be a tuple). The optional kwargs argument specifies a dictionary of keyword arguments. When the function returns, the thread silently exits. When the function terminates with an unhandled exception, a stack trace is printed and then the thread exits (but other threads continue to run).

_thread.interrupt_main()

Raise a KeyboardInterrupt exception in the main thread. A subthread can use this function to interrupt the main thread.

_thread.exit()

Raise the SystemExit exception. When not caught, this will cause the thread to exit silently.

_thread.allocate_lock()

Renvoie un nouvel objet lock. Les méthodes de l'objet lock sont décrites ci-après. Le lock est initialement déverrouillé.

_thread.get_ident()

Return the 'thread identifier' of the current thread. This is a nonzero integer. Its value has no direct meaning; it is intended as a magic cookie to be used e.g. to index a dictionary of thread-specific data. Thread identifiers may be recycled when a thread exits and another thread is created.

_thread.stack_size([size])

Return the thread stack size used when creating new threads. The optional size argument specifies the stack size to be used for subsequently created threads, and must be 0 (use platform or configured default) or a positive integer value of at least 32,768 (32 KiB). If size is not specified, 0 is used. If changing the thread stack size is unsupported, a RuntimeError is raised. If the specified stack size is invalid, a ValueError is raised and the stack size is unmodified. 32 KiB is currently the minimum supported stack size value to guarantee sufficient stack space for the interpreter itself. Note that some platforms may have particular restrictions on values for the stack size, such as requiring a minimum stack size > 32 KiB or requiring allocation in multiples of the system memory page size - platform documentation should be referred to for more information (4 KiB pages are common; using multiples of 4096 for the stack size is the suggested approach in the absence of more specific information).

Disponibilité : Windows et systèmes gérant les fils d'exécution POSIX.

_thread.TIMEOUT_MAX

La valeur maximale autorisée pour le paramètre timeout de la méthode Lock.acquire(). Donner un délai d'attente supérieur à cette valeur lève une OverflowError.

Nouveau dans la version 3.2.

Les verrous (lock objects) ont les méthodes suivantes :

lock.acquire(waitflag=1, timeout=-1)

Without any optional argument, this method acquires the lock unconditionally, if necessary waiting until it is released by another thread (only one thread at a time can acquire a lock --- that's their reason for existence).

If the integer waitflag argument is present, the action depends on its value: if it is zero, the lock is only acquired if it can be acquired immediately without waiting, while if it is nonzero, the lock is acquired unconditionally as above.

If the floating-point timeout argument is present and positive, it specifies the maximum wait time in seconds before returning. A negative timeout argument specifies an unbounded wait. You cannot specify a timeout if waitflag is zero.

The return value is True if the lock is acquired successfully, False if not.

Modifié dans la version 3.2: Le paramètre timeout est nouveau.

Modifié dans la version 3.2: Lock acquires can now be interrupted by signals on POSIX.

lock.release()

Releases the lock. The lock must have been acquired earlier, but not necessarily by the same thread.

lock.locked()

Return the status of the lock: True if it has been acquired by some thread, False if not.

In addition to these methods, lock objects can also be used via the with statement, e.g.:

import _thread

with a_lock:
print("a_lock is locked while this executes")


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