How does threading in powershell work?

Question

I want to parallelize some file-parsing actions with network activity in powershell. Quick google for it, start-thread looked like a solution, but:

T

Answer 1

The thing that comes closest to threads and is way more performant than jobs is PowerShell runspaces.

Here is a very basic example:

# the number of threads
$count = 10

# the pool will manage the parallel execution
$pool = [RunspaceFactory]::CreateRunspacePool(1, $count)

try {    
    $pool.Open()

    # create and run the jobs to be run in parallel
    $jobs = New-Object object[] $count
    for ($i = 0; $i -lt $count; $i++) {
        $ps = [PowerShell]::Create()
        $ps.RunspacePool = $pool

        # add the script block to run
        [void]$ps.AddScript({
            param($Index)
            Write-Output "Index: $index"
        })

        # optional: add parameters
        [void]$ps.AddParameter("Index", $i)

        # start async execution
        $jobs[$i] = [PSCustomObject]@{
            PowerShell = $ps
            AsyncResult = $ps.BeginInvoke()
        }
    }
    foreach ($job in $jobs) {
        try {
            # wait for completion
            [void]$job.AsyncResult.AsyncWaitHandle.WaitOne()

            # get results
            $job.PowerShell.EndInvoke($job.AsyncResult)
        }
        finally {
            $job.PowerShell.Dispose()
        }
    }
}
finally {
    $pool.Dispose()
}

Beyond that, you can do more advanced things like throttle the number of parallel runspaces on the pool, or import functions and variables from the current session etc.