periodic_executor.py 文件源码

def _shutdown_executors():
    # Copy the set. Stopping threads has the side effect of removing executors.
    executors = list(_EXECUTORS)

    # First signal all executors to close...
    for ref in executors:
        executor = ref()
        if executor:
            executor.close()

    # ...then try to join them.
    for ref in executors:
        executor = ref()
        if executor:
            executor.join(1)

    executor = None