concurrency.py 文件源码

def initialize_exception_listener():  # must be invoked in main thread in "geventless" runs in order for raise_in_main_thread to work
    global REGISTERED_SIGNAL
    if REGISTERED_SIGNAL:
        # already registered
        return

    if threading.current_thread() is not threading.main_thread():
        raise NotMainThread()

    def handle_signal(sig, stack):
        global LAST_ERROR
        error = LAST_ERROR
        LAST_ERROR = None
        if error:
            raise error
        raise LastErrorEmpty(signal=sig)

    custom_signal = signal.SIGUSR1
    if signal.getsignal(custom_signal) in (signal.SIG_DFL, signal.SIG_IGN):  # check if signal is already trapped
        signal.signal(custom_signal, handle_signal)
        REGISTERED_SIGNAL = custom_signal
    else:
        raise SignalAlreadyBound(signal=custom_signal)