Data race in logp.(*FileRotator)

[nrvnrvn]

Seen in https://github.com/mheese/journalbeat/issues/108
A workaround is to turn off logging to files.

==================
WARNING: DATA RACE
Read at 0x00c420139d60 by main goroutine:
  os.(*File).Write()
      /root/.gimme/versions/go1.8.linux.amd64/src/os/file.go:139 +0x70
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.(*FileRotator).WriteLine()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/file_rotator.go:71 +0x138
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.send()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/log.go:90 +0x235
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.msg()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/log.go:115 +0xbf
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.Info()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/log.go:120 +0x7e
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/beat.(*Beat).launch()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/beat/beat.go:221 +0x934
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/beat.Run()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/beat/beat.go:141 +0x72
  main.main()
      /go/src/github.com/mheese/journalbeat/main.go:25 +0x65

Previous write at 0x00c420139d60 by goroutine 17:
  os.NewFile()
      /root/.gimme/versions/go1.8.linux.amd64/src/os/file_unix.go:56 +0x85
  os.OpenFile()
      /root/.gimme/versions/go1.8.linux.amd64/src/os/file_unix.go:123 +0x21b
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.(*FileRotator).Rotate()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/file_rotator.go:148 +0x1ae
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.(*FileRotator).WriteLine()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/file_rotator.go:64 +0x260
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.send()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/log.go:90 +0x235
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.msg()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/log.go:115 +0xbf
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.Info()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/log.go:120 +0x7e
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.logMetrics()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/metrics.go:23 +0x12f

Goroutine 17 (running) created at:
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp.Init()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/logp/logp.go:161 +0x386
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/beat.(*Beat).configure()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/beat/beat.go:277 +0x422
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/beat.(*Beat).launch()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/beat/beat.go:170 +0xcb
  github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/beat.Run()
      /go/src/github.com/mheese/journalbeat/vendor/github.com/elastic/beats/libbeat/beat/beat.go:141 +0x72
  main.main()
      /go/src/github.com/mheese/journalbeat/main.go:25 +0x65
==================

[ph]

I am able to reproduce that issue in the 5.6 branch, I'll do a bit more digging, I have seen that you have referenced this issue https://github.com/mheese/journalbeat/issues/100 as the fix, but it doesn't seem to work on my side.

[ph]

This race has been fixed in #4519, but the commit only went into master. @exekias Can you backport that to 5.6?

[exekias]

Just opened #5409, sorry for the delay, I missed this ping somehow 😇

[ph]

#5409 was merged in the 5.6 branch, closing this.