[PD] Strange real time behavior with pd-extended + Jack + Libraries

Martin Schied crinimal at gmx.net
Thu Apr 2 17:19:54 CEST 2009

Hi all.

I'm running Ubuntu Intrepid 2.6.27-3-rt #1 PREEMPT RT and having some 
strange things happening when loading libraries like GEM, pdp or pidip 
together with using real time priority for jack and pd:

starting jack: jackd -R -d alsa
starting pd: /usr/bin/pd -jack -rt -channels 2 -noprefs -stderr

then i make a new patch and create [Gem]
it takes some time (hard disk working) and then everything's fine.

then i close pd, start pd again like above, again create [Gem] (this 
time no noticeable harddisk action, files are cached) and pd crashes:

GEM: using MMX optimization
cannot read server event (Connection reset by peer)
zombified - calling shutdown handler
watchdog: signaling pd...
watchdog: signaling pd...

I can avoid this crash by different things:

start with -nogui
start with channels 0, then creating [Gem] then set up media, jack
start pd without real time priority or start jack without real time 
priority or with -P (priority setting) which gave too much xruns, at 
least with firewire audio.

it also crashes when i start pd without audio, then set up audio in the 
menu and then create [Gem]

I also posted this as bug at the Gem sourceforge page, but then i found 
out that it's not Gem related. As I mentioned before, it also happens 
with pdp / pidip, but Interestingly not every time I create pdp (but 
always together with pidip)

my workaround is now loading all libs at startup and then sending a 
message to pd to setup audio:

[; pd audio-dialog 0 0 0 0 4 0 0 0 0 0 0 0 4 0 0 0 48000(

anyone having similar things happening? i could reproduce it on an other 
pc using ubuntu jaunty, but it didn't happen on hardy. also non-realtime 
kernels give me these problems.


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