Vfrdtyky

When using Powershell Jobs, Runspaces, or Workflows, are the threads being executed on separate cores? (and if so, how do we tell powershell how many cores to use? -- sorry that's 2 questions.)

.Net has the Task Parallel Library, which allows a 'for loop' to run in parallel, using all available cores (here is one example). Does Powershell Jobs, Runspaces, or Workflows do something similar? And by similar, I mean are the threads actually running on separate cores, in parallel?

I found a similar question here, but it seems unclear (to me anyway) if the threads are executed on separate cores. It seems that sometimes multi-threads are mistaken for parallel, as mentioned here.

If using multiple cores with Powershell is not possible, I will use C# or perhaps Python, but my first choice is to use Powershell because (insert long list of reasons).

If it's relevant, I'm trying to do all this to help a co-worker who does server admin type stuff. Currently, his powershell script loops through a list of servers, and foreach server, does stuff. Currently the script runs on an 8 core machine, but is only using one core. I'm sure there are other ways to boost performance, but doing it in parallel is my current goal.

I would say yes if by separate cores, you mean logical cores (not physical cores). Run something like this and notice the output from “$num”. $num represents the current logical (not physical) core on which a thread is running. If this script runs on a dual core machine (with 4 logical cores), the output of $num is a 0, 1, 2, or 3. See here for a better explanation on Logical vs Physical CPU.

$sb = {

    param($sbarg)

$MethodDefinition = @'

[DllImport("kernel32.dll", CharSet = CharSet.Unicode)]

public static extern int GetCurrentProcessorNumber();

'@



    $Kernel32 = Add-Type -MemberDefinition $MethodDefinition -Name 'Kernel32' -Namespace 'Win32' -PassThru



    0..10 | % {

    $num = $Kernel32::GetCurrentProcessorNumber() 

    Write-Output "[$sbarg]:[$_] on '$num'"



    # simulate some work that may make the cpu busy

    # perhaps watch in task manager as well to see load

    $result = 1; foreach ($number in 1..1000000) {$result = $result * $number};



    Start-Sleep -Milliseconds 500

    }

}



0..10 | % {

    Start-Job -ScriptBlock $sb -ArgumentList $_

}



Get-Job



# Wait for it all to complete

While (Get-Job -State "Running")

{

    Write-Output "waiting..."

    Start-Sleep 2

}



# Getting the information back from the jobs

Get-Job | Receive-Job



# Clean Up

Get-Job | Remove-Job