As described in issue #2727
https://bugtrack.alsa-project.org/alsa-bug/view.php?id=2727
applications hang after some seconds when using the jack plugin.
Kevin Ross kevin@familyross.net writes:
The cause: The plugin creates a pipe, so that the fd's could be polled to indicate completion of a transfer. However, the call to write() blocks when playing audio, as nothing actually reads from the pipe, and it fills up until it blocks.
Making the socket non-blocking fixes the problem, and testing with playback and capture both work properly for me now.
I've also tested Kevin's patch and confirm it works.
Signed-off-by: Adrian Knoth adi@drcomp.erfurt.thur.de
diff --git a/jack/pcm_jack.c b/jack/pcm_jack.c index 3370a26..a3833c5 100644 --- a/jack/pcm_jack.c +++ b/jack/pcm_jack.c @@ -307,6 +307,18 @@ static int parse_ports(snd_pcm_jack_t *jack, snd_config_t *conf) return 0; }
+static int make_nonblock(int fd) { + int fl; + + if ((fl = fcntl(fd, F_GETFL)) < 0) + return fl; + + if (fl & O_NONBLOCK) + return 0; + + return fcntl(fd, F_SETFL, fl | O_NONBLOCK); +} + static int snd_pcm_jack_open(snd_pcm_t **pcmp, const char *name, snd_config_t *playback_conf, snd_config_t *capture_conf, @@ -363,6 +375,9 @@ static int snd_pcm_jack_open(snd_pcm_t **pcmp, const char *name,
socketpair(AF_LOCAL, SOCK_STREAM, 0, fd); + make_nonblock(fd[0]); + make_nonblock(fd[1]); + jack->fd = fd[0];
jack->io.version = SND_PCM_IOPLUG_VERSION;