App deadlock on android when call SDL_LockAudioDevice (sdl2.0.8))

SDL Development
1

my app deadlock on android when call SDL_LockAudioDevice (sdl2.0.8)), I did not call SDL_LockAudioDevice in callbackfunction

here is my callbackfunction(SDL_AudioCallback):

    void SDLAudio::sdl_audio_callback(void *opaque, Uint8 *stream, int len)
	{
		SDLAudio* sa = (SDLAudio*)opaque;
		bool mute = true;
		bool clean = true;
		std::unordered_map<unsigned int, MediaState*>::iterator iter;
		for (iter = sa->_AudioMap.begin(); iter != sa->_AudioMap.end(); iter++)
		{
			bool is_mute = iter->second->sdl_audio_callback(stream, len, clean);
			clean = false;
			if (!is_mute)
			{
				mute = false;
			}
		}

		if (mute)
		{
			memset(stream, 0, len);
		}
	}

and here is my function which include SDL_LockAudioDevice

    void SDLAudio::close_audio(unsigned int id)
	{
        SDL_LockAudioDevice(_audio_dev);
		std::unordered_map<unsigned int, MediaState*>::iterator got = _AudioMap.find(id);
		if (got != _AudioMap.end())
		{
			_AudioMap.erase(id);
		}
        SDL_UnlockAudioDevice(_audio_dev);
	}