Are there any hosts (de)constructing plugins on different threads?

Hello JUCErs,

I’ve tested with Ableton Live 9 and it seems to construct and deconstruct the plugins on the same thread (and so does the JUCE sample Plugin Host - it does it on the Juce Message thread).

My plugins register with a shared resource upon construction and deregister from it on deletion, but I have no guards for threading issues in the resource in question.

And this seems like a good convention (init and delete on the Message Thread), but conventions are often ignored - are there any hosts that don’t follow this guide-line and actually (de)construct plugins in-parallel?


In my experience, most DAWs will play it safe and use the same thread for this, and usually that’ll be the message thread.

If you want a good test case, try it in WaveLab, which tends to be pretty free-and-easy about how it chooses to use threading.

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Tested with 64bit WaveLab Elements 9.0.20 - init and delete is done on the same thread.

Thanks @jules.

I would suggest testing with Apple Final Cut Pro, I recall that a lot of multi-threading happens there, but I suspect the destructing is still on the same thread. A good test for a plug-in in general however is to load several instances each with automation, hold the space-bar to constantly trigger the pay/pause of audio and open and close the GUI’s as much and as fast as possible, very good stress test!


Yeah, test it in Final Cut Pro X and optimize for this host! In my experience it is quite a bad/different host for audio plugins (i.e. it might crash, even if your plugin is a totally valid AU and rock solid in every other host).

If you move the play-head and the option ‘Audio Skimming’ is on (on by default), for each audio snippet you hear (approx. 10 a second) a new instance of your plugin will be created and destroyed. This is quite a stress test for your plugin.

A 30 day trial version of Final Cut Pro X is available at On each minor update of FCPX you can run the new trial version for another 30 days. Or ask Apple to get the full version for testing. You might be lucky.

@anthony-nicholls : Does automation in FCPX with your plugin really work? It seems that JUCE has an issue with automation in FCPX. Please take a look at my earlier post about it: AAX plugin, automation gets all messy after a while
Sadly it didn’t got any attention by the JUCE devs.


That’s a good question Samuel I haven’t run up FCPX for a while, to be honest when I last done some serious testing with it I wasn’t testing plugins made with JUCE.

OK I passed this to QA and it seems we do indeed have a problem with automation in FCPX with plugins using JUCE, much like you have reported.