Wrong hang detected when HangReporter.detect() is called with unexpected interval

[mega-yfa]

I found that DispatchSourceTimer callback on hangReporter.detect() is not always in detectionTimerInterval, which will result in wrong hang detected. That means perfsuite will callback nonfatal hang received when iOS system hang detection not reporting any hang.

Have you ever came into this kind of issue?

[pilot34]

Hey, sorry for the long reply. I somehow do not get any notifications about the new issues.

I didn't notice any major false-positives. The idea for this hang detection is not to fix every single hang that occured. But look at the large numbers and fix if we see some spikes. So it can be some random individual hangs detected from random places, but if we see tens or hundreds hangs with the same stack trace, we can know, that this is the issue somewhere.

It may be that iOS hang detection uses a bit more sophisticated algorithms. For example it can skip some hangs which are happening when CPU is busy with some another process, so it wasn't caused by the app's code, but by the system. Or some other tricks. We do not have access to such algorithms. But on the other hand we can get those hangs live from production.

If you notice any particular false-positive or wrong behavior, please report. I will try to reproduce and fix.