PR Summary

This is a fix for the ForEach-Object perf Issue: #10450.

measure-command { 1..254 | foreach -Parallel {ping "192.168.0.$_" -n 1 | where {$_ -match "ttl="}} -ThrottleLimit 300 }

# Time for ThreadJob and ForEach -Parallel -AsJob is around 8 seconds
# Time for ForEach -Parallel is around 60 seconds

PR Context

The problem was that the number of concurrent runspaces was being limited to around 40-50, even though the ThrottleLimit was set to 300. It turns out it was the Cmdlet input processing thread that was causing the bottleneck. I don't know what the conflict is while spinning up runspaces, but the fix is to now do this on a dedicated thread similar to how it currently works for -AsJob.

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