thread.py 文件源码

def __init__(self, max_workers=None):
        """Initializes a new ThreadPoolExecutor instance.

        Args:
            max_workers: The maximum number of threads that can be used to
                execute the given calls.
        """
        if max_workers is None:
            # Use this number because ThreadPoolExecutor is often
            # used to overlap I/O instead of CPU work.
            max_workers = (cpu_count() or 1) * 5
        if max_workers <= 0:
            raise ValueError("max_workers must be greater than 0")

        self._max_workers = max_workers
        self._work_queue = queue.Queue()
        self._threads = set()
        self._shutdown = False
        self._shutdown_lock = threading.Lock()