[SOLVED] Ardour 5 hangs in certain sessions

Okay, so the topic title speaks for itself - yes, Ardour just hangs.
While in the session, working on some music, Ardour can completely hang for a while and then go back to normal state. This happens in some sessions, and in some it’s not happening at all.
It’s not random though - I can surely tell that this happens once in 20 or 30 seconds and interface hangs for 5 or 10 seconds. And every time it hangs I can hear CPU load spikes - fan inside my PC just shouts “OMG SWITCH THAT THING OFF”.
I’m suspicious of some plugins, but can’t tell if they are really causing this effect since Ardour has no feature to show CPU load of each plugin. It also seems that if I bypass all plugins in the session - problem will not occur. How can I check which of the plugins causing this problem?

I’ve disabled periodic saves and problem’s gone.

Save a copy of the session, close the session and open the copy. Then remove the plugins one by one until the problem dissappears.


Doesn’t the Task Manager show plugins as their own tasks? You can sort the tasks by CPU usage and use that to identify the problem.

Nope. Ardour runs all plugins without context switch in the realtime-process thread(s).

Task (or process) switching would introduce significant overhead.

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Is this only the GUI and does Audio playback continue unaffected?

If so this may be a perdiod save operation (Ardour saves backups every 2 minutes if the session is modified and not record armed) . Perhaps some Plugin state save takes ages, eg. a VST sampler storing its samples with ardour’s session state).

yup, it is only gui-related. Audio keeps going. Almost every time when this happens plugins gui is unaffected too.

Nice, but takes lot of time to do that.

I’ve tried to disable automatic backups in one session (it has less hang problems, but whatever) and for now it seems like a solution. I can’t say that problem is solved thought since I haven’t tried it on problematic session yet.
I’ll report on that in a few days.