basic-station: concurrent write to websocket connection

[fancar]

Hello Brocaar!
Recently I faced the issue. It happens when a gateway is under heavy load (~250-300 messages per min)

panic: concurrent write to websocket connection

goroutine 96544 [running]:
github.com/gorilla/websocket.(*messageWriter).flushFrame(0x2ab1724, 0x1, 0x0, 0x0, 0x0, 0xf14ee1ea, 0x52d33c)
/home/fancar/go/pkg/mod/github.com/gorilla/websocket@v1.4.2/conn.go:610 +0x590
github.com/gorilla/websocket.(*Conn).WriteMessage(0x28a69c0, 0x9, 0x0, 0x0, 0x0, 0x3b9aca00, 0x0)
/home/fancar/go/pkg/mod/github.com/gorilla/websocket@v1.4.2/conn.go:763 +0x1c8
github.com/brocaar/chirpstack-gateway-bridge/internal/backend/basicstation.(*Backend).websocketWrap.func2(0x2955340, 0x28a69c0, 0x28948c0, 0x2ab6340)
/home/fancar/dev/iot/chirp/chirpstack-gateway-bridge/internal/backend/basicstation/backend.go:833 +0x18c
created by github.com/brocaar/chirpstack-gateway-bridge/internal/backend/basicstation.(*Backend).websocketWrap
/home/fancar/dev/iot/chirp/chirpstack-gateway-bridge/internal/backend/basicstation/backend.go:827 +0x240

[brocaar]

Hi @fancar any reason why you closed the PR? Is it because your solution did not fix the issue, or is the issue no longer valid?

[brocaar]

@fancar I believe the above commit should fix the issue.

[fancar]

I closed it because It didn't pass the test. You can check the last commit in the same branch of fork tho. It works for me.
Thank you for your solution.

ps There is some memory leak problem I faced too. I'll send a new pull request as soon as I catch it.