I would try an external sampling. The stack trace you are looking at is somewhat artificial. A native sampling will help pin down what exactly is consuming the cpu (switching to thread mode in htop can be a substitute). You might also run strace on the pid when it gets in this state to give additional clues.
> On Oct 25, 2022, at 7:28 PM, Steven Sokol <st...@stevensokol.com> wrote: > > I don't think so. I don't have it capped in the systemd configuration and > it's not using very much memory even in the runaway state. Here's a > screenshot of htop - check out the fvUnisocket process at the top of the list: > > https://user-images.githubusercontent.com/350268/197785991-a8a9691b-4499-4e7a-b0c5-557ef2924514.png > > > On Tuesday, October 25, 2022 at 6:42:14 PM UTC-5 ren...@ix.netcom.com wrote: > Are you certain you haven’t capped the memory and all of the GC threads are > spinning trying to claim/allocate memory? > > >> On Oct 25, 2022, at 4:49 PM, Steven Sokol <st...@stevensokol.com >> <applewebdata://C15A70EA-E4EF-48C1-8D50-4CB99C258AD4>> wrote: >> > >> Weird one. I have a go application that, on occasion, will suddenly jump >> from some very low CPU usage (1% - 10%) to 400% (4 core system). I run this >> app at a heightened priority and it can nearly lock the machine (Pi CM4) up. >> >> I can kill it with SIGKILL and I'm able to get a stack trace by sending >> SIGQUIT. (Here's a gist >> <https://gist.github.com/ssokol/b168de8b4546efd9b43a9d6af8538de9> of the >> stack trace.) >> >> The trace would seem to indicate that everything is idle - virtually all the >> goroutines are in runtime.gopark. None of them ever get out of it. I've >> tried adding a watchdog timer and it locks up along with all the other >> goroutines, so it never fires once the runaway event starts. >> >> The app itself isn't anything special. It listens for data on a set of about >> 16 Redis pubsub channels and forwards any data it receives to a very >> limited number of clients over UDP. Throughput ranges from 34 - 38 KB/sec, >> and the message counts are in the hundreds. Most of the time it eats about >> 5% of one core on the CM4. >> >> I guess this could be an error on my part, but there's nothing in my code >> that seems likely to cause this - no obvious place for a multi-threaded >> tight loop. I thought for a while that it might be some sort of an issue in >> Redigo (golang redis client) but from what that stack trace shows, it looks >> like all the redis listeners are happy and healthy and stuck waiting in >> gopark along with all the other goroutines. >> >> Has anyone seen this kind of weird before? >> >> Thanks, >> >> -S >> >> > >> -- >> You received this message because you are subscribed to the Google Groups >> "golang-nuts" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to golang-nuts...@googlegroups.com >> <applewebdata://C15A70EA-E4EF-48C1-8D50-4CB99C258AD4>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/5465198d-9a48-4db1-98d5-498922b1ac39n%40googlegroups.com >> >> <https://groups.google.com/d/msgid/golang-nuts/5465198d-9a48-4db1-98d5-498922b1ac39n%40googlegroups.com?utm_medium=email&utm_source=footer>. > > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com > <mailto:golang-nuts+unsubscr...@googlegroups.com>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/382df009-cd81-4f62-ae67-03dfc1bb338en%40googlegroups.com > > <https://groups.google.com/d/msgid/golang-nuts/382df009-cd81-4f62-ae67-03dfc1bb338en%40googlegroups.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/A2B7C1F5-375E-4B04-8154-1271776A0B6B%40ix.netcom.com.
