races in console trace while running Shell.Exec

[zhongjn]

Description

While running commands with Shell.Exec, output from stdout or stderr gets wrong.

Repro steps

1. Step A Prepare a bash script err.sh:

   >&2 echo err1 # writes to stderr
   >&1 echo out1 # writes to stdout
   >&2 echo err2
   >&1 echo out2
   sleep 1

2. Step B Use Shell.Exec to execute the bash script. I executed the script multiple times here to make the problem more obvious.

   Shell.Exec("bash", "scripts/err.sh") |> ignore
   Shell.Exec("bash", "scripts/err.sh") |> ignore
   Shell.Exec("bash", "scripts/err.sh") |> ignore

Expected behavior

Output are colored accordingly. Lines are not messed up.

Actual behavior

Known workarounds

Please provide a description of any known workarounds.

Related information

• Operating system: Ubuntu 20.04
• .NET Runtime: 6.0
• Version of FAKE: latest

[github-actions[bot]]

Welcome to the FAKE community! Thank you so much for creating your first issue and therefore improving the project!

[zhongjn]

The root cause shold be:

1. While running the command, callbacks are executed in different threads:

https://github.com/fsprojects/FAKE/blob/79aa1273d0311595bd404be5721d994301774552/src/app/Fake.Core.Process/Process.fs#L843-L850

2. Trace is not thread-safe, since ConsoleTraceListener is not thread-safe:

https://github.com/fsprojects/FAKE/blob/79aa1273d0311595bd404be5721d994301774552/src/app/Fake.Core.Trace/TraceListener.fs#L273-L308

Could we simply make ConsoleTraceListener thread-safe to fix this problem? If so, i could make a PR to fix this.

[yazeedobaid]

Thanks for reporting. Can you please use the create process API instead? Since the asyncShellExex is marked with an obsolete attribute. https://github.com/fsprojects/FAKE/blob/79aa1273d0311595bd404be5721d994301774552/src/app/Fake.Core.Process/Process.fs#L826-L829