I am in the process of porting my AU host from the AUv2 to the AUv3 API and, since AUv3 Audio Units run in a separate process, I was hoping to be able to recover gracefully from plug-in crashes. If memory serves well, this was even one of the advantages of AUv3 touted by Apple when they were first introduced a few years back.
Unfortunately, a few days of experimentation have left me rather frustrated. What seems to happen is that if an AUv3 effect crashes in the middle of processing audio, then its renderBlock gets stuck forever on a semaphore waiting for a signal that never comes. This would be bad enough by itself, but has the rather nasty side effect of causing a deadlock as soon as the host sends pretty much any message to the AUAudioUnit instance, including trying to release it or to invalidate its resources. Note that Apple's own AUv3Host sample code freezes when faced with a crashing AUv3 Audio Unit.
My current workaround is to detect the crash by listening to kAudioComponentInstanceInvalidationNotification and then leak the AUAudioUnit object on purpose and ask the user to relaunch the application. This seems to work but is clearly a horrible hack. So my question is whether anyone with experience hosting AUv3 effects knows how to gracefully recover from a crash of the effect without creating unwelcome side effects like blocked threads / leaked objects / etc?
Thanks a lot! Best,
Martin
Unfortunately, a few days of experimentation have left me rather frustrated. What seems to happen is that if an AUv3 effect crashes in the middle of processing audio, then its renderBlock gets stuck forever on a semaphore waiting for a signal that never comes. This would be bad enough by itself, but has the rather nasty side effect of causing a deadlock as soon as the host sends pretty much any message to the AUAudioUnit instance, including trying to release it or to invalidate its resources. Note that Apple's own AUv3Host sample code freezes when faced with a crashing AUv3 Audio Unit.
My current workaround is to detect the crash by listening to kAudioComponentInstanceInvalidationNotification and then leak the AUAudioUnit object on purpose and ask the user to relaunch the application. This seems to work but is clearly a horrible hack. So my question is whether anyone with experience hosting AUv3 effects knows how to gracefully recover from a crash of the effect without creating unwelcome side effects like blocked threads / leaked objects / etc?
Thanks a lot! Best,
Martin
