Parallelisation with PowerShell and Jobs

parallel.ps1

# Remove previous jobs first
Get-Job | Remove-Job

$runs = 100
$maxThreads = 10
$start = [datetime]::Now
$c = 0  # completed jobs
$sum = 0 # sum of results

for ( $i = 0; $i -lt $runs; $i++ ) {

    # Automatic throttling
    while ( @( Get-Job -State Running ).Count -ge $maxThreads ) {
        
        # Check current job status while waiting
        Get-Job -State Completed | Receive-Job -AutoRemoveJob -Wait | ForEach-Object {
            $c += 1
            $sum += $_
            "Returned $( $c ) jobs"
        }
        
        Start-Sleep -Milliseconds 200
        
    }

    # put a variable like `$j =` in front or `[void]()` around to suppress output
    #[void](
        Start-Job {

            Start-Sleep -Seconds 5

            If ( $using:i -eq 3 ) {
                throw "Oh no!"
            }

            $using:i # using a variable from "outside"

        }
    #)


    
}

# Wait and get the last results
Get-Job | Wait-Job | Where-Object { $_.State -eq "Completed" } | Receive-Job -AutoRemoveJob -Wait | ForEach-Object {
    $c += 1
    $sum += $_
}

# Check if there are more jobs left to check
Get-Job | ForEach-Object {
    $_
}

# Check the result with
$sumCheck = 0; 0..($runs - 1) | % { $sumCheck += $_ }; $sumCheck -= 3 # because the 3rd job throws an exception
"Total sum of $( $sum )"

If ( $sum -eq $sumCheck ) {

    "The result is correct"

} else {

    "The result is not correct"

}

$ts = New-TimeSpan -Start $start -end ( [datetime]::Now )
"Total: $( $ts.TotalSeconds ) seconds"