go: sync: Map.Store() crash with fatal error: sync: unlock of unlocked mutex

Hi,

For some reason our service crashes with this unrecoverable error:

 fatal error: sync: unlock of unlocked mutex
goroutine 866557 [running]: 
runtime.throw(0xc0236c, 0x1e)
	/opt/go1.10.3.linux-amd64/src/runtime/panic.go:616 +0x81 fp=0xc44a9d65c0 sp=0xc44a9d65a0 pc=0x42b191 
sync.throw(0xc0236c, 0x1e)
	/opt/go1.10.3.linux-amd64/src/runtime/panic.go:605 +0x35 fp=0xc44a9d65e0 sp=0xc44a9d65c0 pc=0x42b105 
sync.(*Mutex).Unlock(0xc42522c050)
	/opt/go1.10.3.linux-amd64/src/sync/mutex.go:184 +0xc2 fp=0xc44a9d6608 sp=0xc44a9d65e0 pc=0x46c652 
sync.(*Map).Store(0xc42522c050, 0xabd0c0, 0xc4374e15a0, 0xbabe00, 0xc4305738c0) 
	/opt/go1.10.3.linux-amd64/src/sync/map.go:162

we are using sync.Map as intended (filling the map from multiple go routines).

it’s very random, and i can’t force the crash, but it happens many times per day.

Thanks

About this issue

Original URL
State: closed
Created 6 years ago
Comments: 15 (9 by maintainers)

Most upvoted comments

Yes, I think Flush is the issue. If there are outstanding map operations currently in progress on global.StatsManager.items, you can’t do global.StatsManager.items = sync.Map{}. Although technically that doesn’t violate the rule “don’t copy a map before first use” because the map you’re copying hasn’t been used yet. But you’re copying onto an in-use Map, which is also bad. It may be worth adding something to the doc, although it seems pretty obvious that’s unsafe if you think about it long enough. @bcmills

randall77 on Jul 19, 2018

Speaking of which, the race detector should have caught this bug. Have you tried running with the race detector on?

randall77 on Jul 19, 2018