Method __init__

Lib/concurrent/futures/thread.py:161–197

Initializes a new ThreadPoolExecutor instance. Args: max_workers: The maximum number of threads that can be used to execute the given calls. thread_name_prefix: An optional name prefix to give our threads. initializer: A callable used to i

(self, max_workers=None, thread_name_prefix='',
                 initializer=None, initargs=(), **ctxkwargs)

        return WorkerContext.prepare(initializer, initargs)

    def __init__(self, max_workers=None, thread_name_prefix='',
                 initializer=None, initargs=(), **ctxkwargs):
        """Initializes a new ThreadPoolExecutor instance.

        Args:
            max_workers: The maximum number of threads that can be used to
                execute the given calls.
            thread_name_prefix: An optional name prefix to give our threads.
            initializer: A callable used to initialize worker threads.
            initargs: A tuple of arguments to pass to the initializer.
            ctxkwargs: Additional arguments to cls.prepare_context().
        """
        if max_workers is None:
            # ThreadPoolExecutor is often used to:
            # * CPU bound task which releases GIL
            # * I/O bound task (which releases GIL, of course)
            #
            # We use process_cpu_count + 4 for both types of tasks.
            # But we limit it to 32 to avoid consuming surprisingly large resource
            # on many core machine.
            max_workers = min(32, (os.process_cpu_count() or 1) + 4)
        if max_workers <= 0:
            raise ValueError("max_workers must be greater than 0")

        (self._create_worker_context,
         self._resolve_work_item_task,
         ) = type(self).prepare_context(initializer, initargs, **ctxkwargs)

        self._max_workers = max_workers
        self._work_queue = queue.SimpleQueue()
        self._idle_semaphore = threading.Semaphore(0)
        self._threads = set()
        self._broken = False
        self._shutdown = False
        self._shutdown_lock = threading.Lock()
        self._thread_name_prefix = (thread_name_prefix or
                                    ("ThreadPoolExecutor-%d" % self._counter()))

    def submit(self, fn, /, *args, **kwargs):
        with self._shutdown_lock, _global_shutdown_lock: