forceLock hanging in v1.8.3 and causing a goroutine leak

[jacobalberty]

I've only just noticed this and have only been able to confirm it was introduced in v1.8.3 I have not been able to determine if it's a mistake in my using of the library or even make a good test case yet.

upgrading to v1.8.3 has introduced an issue where I end up with a bunch of goroutines that seem to be blocking in forceLock in conn_notjs.go. The following is my pprof output

48 @ 0x436c00 0x4050bd 0x404e85 0x9f2324 0x9f2302 0x9f7ed7 0x466611
#	0x9f2323	nhooyr.io/websocket.(*mu).forceLock+0x43	nhooyr.io/websocket@v1.8.3/conn_notjs.go:234
#	0x9f2301	nhooyr.io/websocket.(*msgReader).close+0x21	nhooyr.io/websocket@v1.8.3/read.go:112
#	0x9f7ed6	nhooyr.io/websocket.(*Conn).close.func1+0x46	nhooyr.io/websocket@v1.8.3/conn_notjs.go:144

[nhooyr]

Hmm, will take a look.

This function is trying to lock the read channel so that it can add back the bufio.Reader into the pool. It looks like there is another goroutine with the lock that hasn't let it go yet or there's a bug where the lock is left acquired.

[jacobalberty]

I'm in the middle of refactoring the a bunch of code including the code around my websocket stuff. I planned to do the websocket stuff last and take a closer look then to see if I can make a good test case.

Whole reason I'm refactoring is to make it easy to add test cases and have them get reported further back for watchdogs to report to me and heal the service, so good time to run into an issue like this lol.

[nhooyr]

Sounds good, def lemme know once you can reliably reproduce.

[nhooyr]

Does v1.8.2 work fine?

[nhooyr]

Also, how do you know they're blocking via the pprof?

I took a look at the code and every codepath that acquires the lock also defers an unlock it so it shouldn't be possible to lock the read lock but then never unlock it.

[nhooyr]

Found it.

[nhooyr]

Please test master and lmk if it fixes things :)

[jacobalberty]

Testing now on master, and yes it worked fine on 1.8.2 I rolled back to it to fix initially.

[jacobalberty]

Master looks good, so far after 30 minutes of testing no issues. It was previously leaking goroutines within 5 minutes of launch.

[nhooyr]

Awesome :)

Will tag a release tonight/tomorrow 🎊

[nhooyr]

Published v1.8.4