ms.ps1

$throttleLimit = 4
$SessionState = [system.management.automation.runspaces.initialsessionstate]::CreateDefault()
$Pool = [runspacefactory]::CreateRunspacePool(1, $throttleLimit, $SessionState, $Host)
$Pool.Open()
 
$ScriptBlock = {
    param($id)
 
    Start-Sleep -Seconds 2
    "Done processing ID $id"
}
 
$threads = @()
 
$handles = for ($x = 1; $x -le 40; $x++) {
    $powershell = [powershell]::Create().AddScript($ScriptBlock).AddArgument($x)
    $powershell.RunspacePool = $Pool
    $powershell.BeginInvoke()
    $threads += $powershell
}
 
do {
    $i = 0
    $done = $true
    foreach ($handle in $handles) {
        if ($null -ne $handle) {
            if ($handle.IsCompleted) {
                $threads[$i].EndInvoke($handle)
                $threads[$i].Dispose()
                $handles[$i] = $null
            }
            else {
                $done = $false
            }
        }
        $i++
    }
    if (-not $done) { Start-Sleep -Milliseconds 500 }
} until ($done)