What happens when AUHostingService crashes?

[dmitch57]

I've been seeing many crashes of AUHostingServiceXPC_arrow every day. Maybe 10 crashes in a 4-hour work session. 

For some, the crashing thread looks like this:
Thread 10 Crashed:: JUCE Timer
0   libsystem_pthread.dylib                  0x1825e3600 pthread_mutex_lock + 12
1   ShaperBox                                0x284a3cc7c 0x2848a8000 + 1657980
2   ShaperBox                                0x284a3f090 0x2848a8000 + 1667216
3   ShaperBox                                0x284a0c7e8 0x2848a8000 + 1460200
4   libsystem_pthread.dylib                  0x1825e9034 _pthread_start + 136
5   libsystem_pthread.dylib                  0x1825e3e3c thread_start + 8
 

Or like this:
Thread 0 Crashed::  Dispatch queue: com.apple.main-thread
0   CoreFoundation                           0x1827f9598 _CFXNotificationRegistrarAddObserver + 152
1   CoreFoundation                           0x1827f9484 CFXNotificationRegistrarAdd + 580
2   CoreFoundation                           0x182684b1c _CFXNotificationRegisterObserver + 252
3   Foundation                               0x18378a4f8 -[NSNotificationCenter addObserverForName:object:queue:usingBlock:] + 208
4   AppKit                                   0x185eacc18 -[NSView _commonAwake] + 644
5   AppKit                                   0x185eb1e84 -[NSView initWithFrame:] + 136
6   AppKit                                   0x185ef0944 -[NSCustomView nibInstantiateWithObjectInstantiator:] + 572
7   AppKit                                   0x185e8140c -[NSIBObjectData instantiateObject:] + 172
8   AppKit                                   0x185e80f5c -[NSIBObjectData nibInstantiateWithOwner:options:topLevelObjects:] + 600
9   AppKit                                   0x185ee7bd8 -[NSNib _instantiateNibWithExternalNameTable:options:] + 332
10  AppKit                                   0x185ee79c4 -[NSNib _instantiateWithOwner:options:topLevelObjects:] + 132
11  AppKit                                   0x185ee732c -[NSViewController loadView] + 296
12  AppKit                                   0x185ee7128 -[NSViewController _loadViewIfRequired] + 72
13  AppKit                                   0x1863a2bbc __24-[NSViewController view]_block_invoke + 28
14  AppKit                                   0x185ee0ab0 NSPerformVisuallyAtomicChange + 108
15  AppKit                                   0x185ee7098 -[NSViewController view] + 160
16  Logic Pro X                              0x102b40594 0x102194000 + 10143124
17  Logic Pro X                              0x102b41358 0x102194000 + 10146648
18  Logic Pro X                              0x1033e3d14 0x102194000 + 19201300
...yadda yadda

Sometimes it's in Amplitube. 

Anyway, Logic seems to plug along and not be fatally affected by this. (Though I do see many LP crashes every day, that's a different matter. I think.). 

Two questions:

1. What's the difference between AUHostingServiceXPC_arrow and AUHostingService? ActivityViewer only shows the latter of these two. I don't run anything with Rosetta.
2. More important to me: what happens when AUHostingServiceXPC_arrow crashes? Is that simply a performance hit? Is it nothing to be alarmed at? How does LP recover from this?

I'm just trying to understand. Any words of wisdom would be appreciated. 

[des99]

16 minutes ago, dmitch57 said:

Thread 10 Crashed:: JUCE Timer

This is a known compatibility problem in JUCE, the main framework that people use to build third-party plugins, which can cause problems.

17 minutes ago, dmitch57 said:

Anyway, Logic seems to plug along and not be fatally affected by this.

Yes, this is the point of hosting plugins outside of Logic - if they crash, Logic doesn't.

AUHostingService hosts Apple silicon native plugins. AUHostingCompatibilityService hosts Intel-only plugins, under Rosetta. This means you can use both plugin types inside Logic running natively.

 

[dmitch57]

7 minutes ago, des99 said:

Yes, this is the point of hosting plugins outside of Logic - if they crash, Logic doesn't.

AUHostingService hosts Apple silicon native plugins

I am aware of all that. Any response to my two actual questions?

[des99]

The Service is generally called AUHostingService. It uses Apple's XPC system, but how files are named or processes are referred to is not really pertinent to anything, nor do I know the developer/Apple naming conventions used.

When it crashes (ie, generally a third-party plugin that is running inside it crashes), doing a "Recover" tries to restart the service and reloads the plugins it was hosting. (I'm not sure exactly the nature of the internal implementation, whether it has to reload everything, or whether it only reloads the crashed plugin and continues as before. It doesn't really matter externally what's going on inside.)

If the crashed plugin restarts normally, everything should be fine. Sometimes it won't, depending on the state of the plugin and the nature of the crash, in which case you can restart Logic, and it will create a new instance of AUHostingService and reload all third-party plugins from scratch.

[dmitch57]

OK, thanks.

[polanoid]

12 hours ago, dmitch57 said:

What's the difference between AUHostingServiceXPC_arrow and AUHostingService?

That doesn't seem to be documented anywhere (forum, please correct me if I'm wrong), so the answer is: we cannot know.

[polanoid]

12 hours ago, dmitch57 said:

what happens when AUHostingServiceXPC_arrow crashes?

The process dies, together with its AU. Logic is not affected apart from the now dead AU (which you can remove and re-add to resurrect it)

[dmitch57]

Based on the contents of my crash logs, I'm pretty sure this AUHostingService crash happens more often than I am explicitly notified by Logic that something has gone wrong (and hence given a chance to recover, or to remove/re-insert the plug-in). I think there may be some auto-recovery happening behind the scenes on Logic's part. 

3 hours ago, polanoid said:

so the answer is: we cannot know

I like the Zen of this. Words to live by. 😀

[des99]

2 minutes ago, dmitch57 said:

I think there may be some auto-recovery happening behind the scenes on Logic's part. 

If you find a concrete example, do let us know so we can understand the behaviour better. 👍

[dmitch57]

14 minutes ago, des99 said:

If you find a concrete example, do let us know so we can understand the behaviour better

All I know for sure is that there are more crashes logged for AUHostingService than Logic is telling me about. E.g., I work for 3 or 4 hours, and there are 10 AUHostingService crashes in the log. And during that time I see one or two "something has gone wrong - recover or quit?" alerts, and three or four crashes of Logic itself (which hopefully are unrelated to AUHostingService, but who knows?). Instances of plugins just going dead (and requiring manual recovery) are rare for me, definitely not every day. It doesn't add up. This happens every day.

What's happening behind the scenes, in the way of auto-recovery, appears to be unknowable until Apple fills us in. 

[polanoid]

44 minutes ago, dmitch57 said:

until Apple fills us in

That's what Apple does. Not.

[EmmanuelD]

Hello.

"Glad" to read I'm not the only one in this situation.

I started a thread via Apple Community.

https://discussions.apple.com/thread/255305659?sortBy=best

With those 2 threads we might be able to help each other.

I should add I'm focusing on my setup working seamlessly and not what it's doing in the back.

Though I'm obviously interested in that part too.

Best.