Access violation (0xC0000005) on Windows when opening two different microphones on separate threads

[lugia19]

Steps to reproduce

Here's some code that reliably causes the issue:

import threading
import speech_recognition as sr

def start_rec(srMic, srRecognizer):
    with srMic as source:
        while True:
            print("Listening for audio...")
            audio = srRecognizer.listen(source)


def main():
    #5 and 1 are both real microphones
    srMic1 = sr.Microphone(device_index=5)
    srRecognizer1 = sr.Recognizer()
    thread1 = threading.Thread(target=start_rec, args=(srMic1, srRecognizer1))

    srMic2 = sr.Microphone(device_index=1)
    srRecognizer2 = sr.Recognizer()
    thread2 = threading.Thread(target=start_rec, args=(srMic2, srRecognizer2))

    thread1.start()
    thread2.start()

    thread1.join()
    thread2.join()

if __name__ == "__main__":
    main()

Expected behaviour

It should begin listening on both devices.

Actual behaviour

I get an access violation.

System information

Running on windows 10, latest version of the library.

Fix

Use a lock to ensure only one thread opens a microphone at a time.

import threading
import speech_recognition as sr
srLock = threading.Lock()

def start_rec(srMic, srRecognizer):
    srLock.acquire()
    with srMic as source:
        srLock.release()
        while True:
            print("Listening for audio...")
            audio = srRecognizer.listen(source)


def main():
    srMic1 = sr.Microphone(device_index=5)
    srRecognizer1 = sr.Recognizer()
    thread1 = threading.Thread(target=start_rec, args=(srMic1, srRecognizer1))

    srMic2 = sr.Microphone(device_index=1)
    srRecognizer2 = sr.Recognizer()
    thread2 = threading.Thread(target=start_rec, args=(srMic2, srRecognizer2))

    thread1.start()
    thread2.start()

    thread1.join()
    thread2.join()

if __name__ == "__main__":
    main()