Goroutine data race

[jovrum]

Using g10k version 0.4.5 Build time: 2018-03-08_14:56:34 UTC:

% g10k -puppetfile -moduledir modules -cachedir .g10k_cache; echo $?
==================
WARNING: DATA RACE
Read at 0x00c4200d0aa0 by main goroutine:
  github.com/xorpaul/g10k/vendor/github.com/henvic/uilive.(*Writer).Flush()
      /home/andpaul/dev/go/src/github.com/xorpaul/g10k/vendor/github.com/henvic/uilive/writer.go:80 +0x29d
  github.com/xorpaul/g10k/vendor/github.com/henvic/uiprogress.(*Progress).Stop()
      /home/andpaul/dev/go/src/github.com/xorpaul/g10k/vendor/github.com/henvic/uiprogress/progress.go:135 +0xad
  github.com/xorpaul/g10k/vendor/github.com/henvic/uiprogress.Stop()
      /home/andpaul/dev/go/src/github.com/xorpaul/g10k/vendor/github.com/henvic/uiprogress/progress.go:67 +0x4a
  main.resolvePuppetfile()
      /home/andpaul/dev/go/src/github.com/xorpaul/g10k/puppetfile.go:338 +0x202d
  main.main()
      /home/andpaul/dev/go/src/github.com/xorpaul/g10k/g10k.go:237 +0x193c

Previous write at 0x00c4200d0aa0 by goroutine 7:
  github.com/xorpaul/g10k/vendor/github.com/henvic/uiprogress.(*Progress).Listen()
      /home/andpaul/dev/go/src/github.com/xorpaul/g10k/vendor/github.com/henvic/uiprogress/progress.go:89 +0xa9

Goroutine 7 (finished) created at:
  github.com/xorpaul/g10k/vendor/github.com/henvic/uiprogress.(*Progress).Start()
      /home/andpaul/dev/go/src/github.com/xorpaul/g10k/vendor/github.com/henvic/uiprogress/progress.go:127 +0xbe
  github.com/xorpaul/g10k/vendor/github.com/henvic/uiprogress.Start()
      /home/andpaul/dev/go/src/github.com/xorpaul/g10k/vendor/github.com/henvic/uiprogress/progress.go:62 +0x4a
  main.resolvePuppetfile()
      /home/andpaul/dev/go/src/github.com/xorpaul/g10k/puppetfile.go:173 +0x2098
  main.main()
      /home/andpaul/dev/go/src/github.com/xorpaul/g10k/g10k.go:237 +0x193c
==================
Resolving Forge modules (3/3)    0s [====================================================================] 100%
Synced ./Puppetfile with 0 git repositories and 3 Forge modules in 0.0s with git (0.0s sync, I/O 0.0s) and Forge (0.0s query+download, I/O 0.0s) using 50 resolv and 20 extract workers
Found 1 data race(s)
66

Puppetfile

mod 'puppetlabs/stdlib'
mod 'puppetlabs/apt'
mod 'puppet-yum'

Not sure how I ended up in this state, but I can reliably reproduce it on my machine (it's deterministic). It only happens when the specified cache is hot/populated, and -verbose is not specified.

[jovrum]

I might have a look at it later but I'll need some time to familiarise myself with Go data races and the race detector. Posted the issue up-front in case this is low hanging fruit for someone else. My issue to PR ratio is admittedly poor :)

[xorpaul]

What exactly are you doing to reproduce this error?

I've tried it several times with a populated cache and removing and not removing the modules directory, but I can't make g10k throw the error.

The stack trace and the fact that this only happens when not specifying the -verbose parameter proves that the race happens when the henvic/uiprogress submodule tries to print the progress bar into your terminal.

Did you try a different terminal? I'll check if there are updates for this submodule available.

[jovrum]

Thanks!

[xorpaul]

I still don't know what exactly is going on with the progress bars and this race condition, but the version I'm currently using (https://github.com/xorpaul/uiprogress) does seem to work.