PowerShell Thread jobs

Start-ThreadJob does what Start-Job does, but in a thread inside the current process instead of a whole new process. It ships with PowerShell 7 and is available for 5.1 from the gallery as the ThreadJob module.

Lesson 2 min read Windows PowerShell 5.1 and PowerShell 7

Documentation: Microsoft Learn

Written and tested by Dhrub Bharali · Updated 02 October 2026

Overview

The difference is cost. A background job spawns a process, which takes a fifth of a second and tens of megabytes. A thread job costs a fraction of that. For fifty short tasks that gap decides whether the script finishes in seconds or minutes.

Everything else is the same: Get-Job, Receive-Job, Wait-Job and Remove-Job all work on thread jobs, so you can swap Start-Job for Start-ThreadJob and keep the rest of the script.

The trade-off is isolation. Threads share the process, so one thread crashing the runtime takes the others with it, and shared state needs care. Use -ThrottleLimit to cap how many run at once, because launching two hundred threads against one machine will hurt rather than help.

Rule of thumb: thread jobs for many short tasks, background jobs when you need one task genuinely isolated.

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Read the command and its supplied arguments. This example requires real PowerShell or its module; this diagram does not execute it.

$targets = 'WEB01' , 'WEB02' , 'SQL01' , 'DC01'
$targets | ForEach-Object {
[pscustomobject]@{
    Target = $_
    Job = 'Start-ThreadJob'
    Cost = 'thread, not process'
  } }

Stage 1$targetsPositional values or no named parameters
Stage 2ForEach-ObjectPositional values or no named parameters

An example to inspect

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$targets = 'WEB01' , 'WEB02' , 'SQL01' , 'DC01'
$targets | ForEach-Object {
[pscustomobject]@{
    Target = $_
    Job = 'Start-ThreadJob'
    Cost = 'thread, not process'
  } }

What happens

This builds one descriptor per target rather than starting real jobs, since jobs would outlive the command. In practice the body would be $targets | ForEach-Object { Start-ThreadJob -ScriptBlock { param($t) Test-Connection $t } -ArgumentList $_ } followed by Get-Job | Wait-Job | Receive-Job.

Worth remembering

Threads instead of processes, so startup is far cheaper.
Built into PowerShell 7; install the ThreadJob module for 5.1.
The same Get-Job, Receive-Job and Wait-Job cmdlets apply.
Cap concurrency with -ThrottleLimit.

Primary documentation

ForEach-Object reference

Try it

Illustrative output · values vary by environment

1PS> $targets = 'WEB01' , 'WEB02' , 'SQL01' , 'DC01'

2PS>

3PS> $targets | ForEach-Object {

4PS> [pscustomobject]@{

5PS> Target = $_

6PS> Job = 'Start-ThreadJob'

7PS> Cost = 'thread, not process'

8PS> } }

Example reader

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$targets = 'WEB01' , 'WEB02' , 'SQL01' , 'DC01'

$targets | ForEach-Object {
  [pscustomobject]@{
    Target = $_
    Job = 'Start-ThreadJob'
    Cost = 'thread, not process'
  } }

Ready to inspect.

Builds one job descriptor per target to show the pattern.

Show reference output