LV2 LinuxSampler debugging

Submitted by zehnan on
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qtractor

Rui,

I tried to do some debugging with qtractor, since I am having a couple of issues with Linuxsampler LV2 plugin. The first thing I noticed is that if I do "gdb qtractor", make a new track on empty canvas, assign it lv2 linuxsampler and activate, everythings locks up. Note, that this does not happen when running qtractor without gdb. When I send SIGINT, the attached stack trace is produced. I am not even sure this is qtractor problem, perhaps I should post this to linuxsampler lists. What do you think?

cheers
Marko

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Submitted by rncbc on Tue, 23 Mar 2010 - 08:19

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It looks like there's some trouble on the linuxsampler-lv2 (re)instantiation code, or at least it doesn't like to get re-instantiated so quickly in succession.

May I ask on how you're inserting the plugin? Is it from the track's mixer strip after you already have added a track or is it while you're at a new track dialog, that is, the track isn't inserted yet but you're adding the lv2 plugin already. I suspect trouble is on this latter case. Try adding the plugin after you add the track, please, and see whether things are any different.

Re. gdb, if you're building with debug information (./configure --enable-debug), some crash stack-tracing code is being included by default which calls gdb directly behind the scenes when a segfault occurs and a clash is certainly due if qtractor is already under gdb control. I won't be surprised if that's what you're experiencing ;)

Cheers

I tried inserting the plugin both ways. It make no difference. And, yes I am using --enable-debug, so this must be it, I just shouldn't run with gdb. :)

So if I wish to debug, I guess the trace is saved to current dir automatically on segfault?

Thanks

Re. if I wish to debug, I guess the trace is saved to current dir automatically on segfault?
- not at all. The stacktrace is just dumped to the console (stdout/err). Ah, it might help if you also turn View/Options.../Display/Capture standard output off, just in case.

Cheers

Submitted by Jaakko Sipari (not verified) on Fri, 30 Jul 2010 - 23:23

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Hi!

I have the same problem with qtractor completely locking when loading LinuxSampler (DSSI or LV2) plugin. As suggested in the previous posts, I turned of "Capture standard output" and the error message coming to the console was something like "cannot bind server socket. retrying in 180". As I suspected from the error message, the problem was that I already had the linuxsampler server running. Killing the linuxsampler instance (which was automatically started by QSampler) before stating qtractor (and loading the plugin) did prevented the crash.

BR, jaakko

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