Hang detection deadlocks when debug is enabled

[noahsmartin]

Platform

iOS

Environment

Develop

Installed

Manually

Version

8.53.2

Xcode Version

16.5

Did it work on previous versions?

No response

Steps to Reproduce

In #4063 we fixed app hang deadlocks when SentryOptions.debug was set to false. However there are still known deadlocks when debug is set to true.

I just ran into one here (note I had made some changes to the code working on some hang detection updates, but the cause of the bug is still present in the latest code on main):

I imagine it's also possible this is the source of some flaky tests

Expected Result

Should not be attempting to symbolicate while threads are suspended, we should instead only do that after retrieving the stack traces and resuming the threads

Actual Result

The app hangs

Are you willing to submit a PR?

No response

[philipphofmann]

@noahsmartin thanks for reporting this. We disable certain features, such as app hang detection, because it can lead to deadlocks when the debugger is attached. See

sentry-cocoa/Sources/Sentry/SentryANRTrackingIntegration.m

Lines 77 to 80 in 43597ba

	- (SentryIntegrationOption)integrationOptions
	{
	return kIntegrationOptionEnableAppHangTracking | kIntegrationOptionDebuggerNotAttached;
	}

and

sentry-cocoa/Sources/SentryCrash/Recording/Monitors/SentryCrashMonitorType.h

Lines 62 to 79 in 43597ba

	#define SentryCrashMonitorTypeAll \
	(SentryCrashMonitorTypeMachException | SentryCrashMonitorTypeSignal \
	| SentryCrashMonitorTypeCPPException | SentryCrashMonitorTypeNSException \
	| SentryCrashMonitorTypeApplicationState)
	#define SentryCrashMonitorTypeDebuggerUnsafe \
	(SentryCrashMonitorTypeMachException | SentryCrashMonitorTypeSignal \
	| SentryCrashMonitorTypeCPPException | SentryCrashMonitorTypeNSException)
	#define SentryCrashMonitorTypeAsyncSafe \
	(SentryCrashMonitorTypeMachException | SentryCrashMonitorTypeSignal)
	#define SentryCrashMonitorTypeAsyncUnsafe \
	(SentryCrashMonitorTypeAll & (~SentryCrashMonitorTypeAsyncSafe))
	/** Monitors that are safe to enable in a debugger. */
	#define SentryCrashMonitorTypeDebuggerSafe \
	(SentryCrashMonitorTypeAll & (~SentryCrashMonitorTypeDebuggerUnsafe))

[itaybre]

We are closing this issue because attaching the debugger should not be used with app hangs.

There is a related issue for the symbolication in #2996 that we will follow up

[noahsmartin]

I don't think this is related to the debugger being attached right? It's just anytime you run the SDK with debug: true. If the debugger is also connected you won't run into it, but you can run with debug: true and the debugger disconnected. @itaybre please let me know if that's not the case and we can re-close, but the way I understand it this is still an issue because it's caused by our "debug" flag, not the debugger.

[philipphofmann]

but the way I understand it this is still an issue because it's caused by our "debug" flag, not the debugger.

Okay, then we can't close it yet, as we still need to fix this issue. Thanks for reopening it @noahsmartin.

[philipphofmann]

We removed the internal symbolication. This issue is fixed with #6562.