Hi.
I want to note that JACK plugin in alsa-plugins in broken. (At least on my two systems.) It just plays for a few seconds and then stops hanging the application that was sending data to it. When it hangs jackd spits out this:
subgraph starting at alsa-jack.jackP.3635.0 timed out (subgraph_wait_fd=7, status = 0, state = Running)
What I want to note is that there is a fix to that and I would like it to be included in the tree. I'm not sure if it doesn't break anything else, but it works for me ok.
Open pcm_jack.c and on the line 146 you'll find:
write(jack->fd, buf, 1); /* for polling */
Deleting this seems to get rid of the problem. So please if you can patch this out. (I didn't make a patch myself since this is so tiny fix that it isn't really worth.)
Cheers.