You’re right. Inspecting the code it is internally partitioned by P. I agree that it looks like the pool is being continually created.
> On Jun 17, 2021, at 12:18 PM, Ian Lance Taylor <i...@golang.org> wrote: > > On Thu, Jun 17, 2021 at 9:19 AM Peter Z <zjy19871...@gmail.com> wrote: >> The original post is on stackoverflow >> https://stackoverflow.com/questions/67999117/unexpected-stuck-in-sync-pool-get >> Golang ENV: >> go1.14.3 linux/amd64 >> Description: >> We have about half a million agents running on each of our machines.The >> agent is written in Go. Recently we found that the agent may get stuck, no >> response for the sent requests. The metrics exported from the agent show >> that a channel in the agent(caching the request) is full. Deep into the >> goroutine stacks, we found that the goroutines consuming messages from the >> channel are all waiting for a lock.The goroutines Stack details are shown >> below. > > That is peculiar. What is happening under the lock is that the pool > is allocating a slice that is GOMAXPROCS in length. This shouldn't > take long, obviously. And it only needs to happen when the pool is > first created, or when GOMAXPROCS changes. So: how often do you > create this pool? Is it the case that you create the pool and then > have a large number of goroutines try to Get a value simultaneously? > Or, how often do you change GOMAXPROCS? (And, if you do change > GOMAXPROCS, why?) > > >> The stack shows that all of the goroutines are waiting for the global lock >> in sync.Pool. But I can't figure out which gouroutine is holding the lock. >> There should be a gouroutine which has `sync.runtime_SemacquireMutex` in >> it's stack not at the top, but there isn't. > > I don't think that is what you would see. I think you would see a > goroutine with pinSlow in the stack but with SemaquireMutex not in the > stack. > > >> Reproduce: >> Can't find a way to reproduce this problem for now. > > It's going to be pretty hard for us to solve the problem without a reproducer. > > Ian > > -- > 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/CAOyqgcW89OSL9frH%3D7f_gMga8qiKQ%2BR6cRnnWK3Kr5dKh3yLsg%40mail.gmail.com. -- 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/EAB0653C-F779-46AB-B41F-CFF323455257%40ix.netcom.com.
