Series of code snippets to help you understand how to do parallel execution in Powershell 5 and 7.
This is a result of my team's work at Abrigo to improve the performance of its upgrade process.
| Powershell 5 | Powershell 7 | |
|---|---|---|
| Based On | .NET Framework | .NET Core 3.x |
| Installation | As part of Microsoft Management Framework or Windows Updates | Separately installable package |
| Installed At | %windir%\System32\WindowsPowerShell\v1.0 | C:\Program Files\Powershell\7 |
| Executable | Powershell.exe | pwsh.exe |
| Pros | Feature complete | Cross-platform Runs side-by-side with other versions |
| Cons | Windows only (5.1 has “core” edition also) |
Not implements all of Powershell 5 capabilities Not behaves exactly the same way as Powershell 5 |
| Parallel Execution Support | Powershell Jobs Invoke-Parallel module |
ForEach-Object -Parallel |
- How to launch powershell code
- How to coordinate multiple executions
- Instantiating new execution
- Waiting for all executions to end
- How to throttle number of maximum concurrency
- How to pass parameters and receive result in multi-threading
- Synchronization (e.g. Mutex)
- How to show the progress of multiple executions on the console
- How to show progress on the console while generating logfile at the same time
- How to pass parameters and receive result in multi-processing
- Gotchas - strange behaviors
- A process begins with a single thread, and can have multiple threads.
- Heap vs. Stack
- A process has its own memory and heap.
- All threads in the same process shares heap (global variables goes in there), but each thread owns its own stack (local variables initiated inside the thread goes in there.)
- Multi-threading vs. Multi-processing
- Multi-threading is lighter since you just instantiate another execution pointer.
- Multi-threading is trickier to achieve, especially if your existing code assumes it is the only consumer of the heap variable.
- Both require careful control over external shared resource, e.g. file.
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Job is Powershell’s multi-processing helper
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Runspace is Powershell’s multi-threading helper
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Invoke-Parallel module uses Runspaces
https://github.com/RamblingCookieMonster/Invoke-Parallel
https://stackoverflow.com/questions/60248354/powershell-jobs-vs-start-process
https://gallery.technet.microsoft.com/Powershell-ISE-Explorer-bfc92307 => very useful add-on if you want to use Windows Powershell ISE
Advanced PowerShell Debugging Techniques (video)
Powershell Debugger Commands Reference
- I don't claim to be a powershell expert. I don't believe I understand its abstration properly, since there are moments that its behavior doesn't make any sense to me. Still, it is just available on every Windows system, thus a great tool to solve my company's problem - we have many on-prem installations on Windows. If you find any incorrect information or useful addition, please let me know or make PR.