zammitt/PowerShellTranscriptIssue

Start/Stop-Transcript Issue

Start/Stop-Transcript does not always capture all output written to the PowerShell console.

When calling a Cmdlet that uses WriteObject to output data, there appears to be a delay that backs up the output pipeline. This results in the output to not be captured when Stop-Transcript is called. Test-TranscriptIssue.cs is an example of such Cmdlet.

How to reproduce

Given the script below (You can easily execute this by launching the project file from this repo in Visual Studio)

Start-Transcript -Path transcript.txt -UseMinimalHeader

Write-Output "Hello from Write-Output"
Write-Host "Hello from Write-Host"

Test-TranscriptIssue

Write-Output "Goodbye from Write-Output"
Write-Host "Goodbye from Write-Host"

Stop-Transcript

# Write out the transcript to the console
cat ./transcript.txt

We get the following output:

There are two interesting observations here:

1. Goodbye from Write-Output is appearing before the output of Test-TranscriptIssue. Is Test-TranscriptIssue introducing a delay to the output pipeline?
2. The output of Test-Transcript and Goodbye from Write-Output is missing from the transcript.

Other notes & thoughts

• We were only able to reproduce this with Cmdlets that use WriteObject (as seen in Test-TranscriptIssue.cs). If we replace Test-TranscriptIssue with Get-Module in the script, everthing seems to work as expected.
• It feels like WriteObject is introducing a delay to the output pipeline that is causing Stop-Transcript to write to file before it is finished processing.
• Is WriteObject the right thing to be using in Cmdlets?