PowerShell Runspaces
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This document discusses multithreading in PowerShell using runspaces. Runspaces allow running PowerShell scripts concurrently by creating new threads within an existing process. This can improve performance over serial execution when tasks take a long time or need to be applied to many targets. While runspaces provide benefits like asynchronous execution and throttling, they also add complexity and need to be properly configured, monitored, and cleaned up. The document provides examples of using runspaces to improve performance of text parsing and master data management tasks.
PowerShell Runspaces
- 1. Multithreading in PowerShell with runspaces 1/18/2017 Drew Furgiuele Senior DBA, IGS Energy
- 2. 1/18/2017 2 About me dfurgiuele@igsenergy.com @pittfurg http://www.port1433.com http://www.genesface.com Contact Info I’m a Senior SQL Server DBA at IGS Energy in Dublin, Ohio. I’ve been using SQL Server since SQL Server 2000 and I love it. I also enjoy DevOps, release management, and PowerShell.
- 3. AGENDA 1/18/2017 3 1. Multithreading in PowerShell: Why? 2. How it works 3. Differences between runspaces and Invoke-Job 4. Examples!
- 4. Multithreading with PowerShell • Most PowerShell scripts execute serially • Which is usually fine! • … Except when it isn’t • Some things don’t always run fast, despite all the optimization in the world • And if something runs “fast” when applied to n+1 targets, it might become slow 1/18/2017 4
- 5. Runspaces – The good • Runspaces spin up new threads on an existing process for parallel execution. • Threads can be invoked asynchronously • Can automatically manage the number of threads executing (so you don’t overwhelm your CPU) • Can return pretty much anything you want 1/18/2017 5
- 6. Runspaces – The not so good 1/18/2017 6 • Can be complex to set up and configure • Need monitored • Need cleaned up • Are hard to troubleshoot • Modules don’t persist
- 7. “… so preoccupied with whether or not you could…” • “…that you didn't stop to think if you should.” • Multithreading is a great tool to keep in your toolbox, but it’s not a hammer looking for a nail • Ever heard of failing at scale? • How about failing at scalex? 1/18/2017 7
- 9. What about Start-Job / Receive-Job? • Start-Job incurs a lot of overhead • No throttling • Same goes for –AsJob and Invoke-Command • Does have a –ThrottleLimit, but that just limits concurrent commands, NOT sessions • How much of a difference? Let’s see it in action. 1/18/2017 9
- 10. Practical Example #1 • Reading Error Logs • Text parsing in PowerShell is an expensive, slow process • Breaking up the workload into threads can vastly improve performance 1/18/2017 10
- 11. Practical Example • Master Data Management 1/18/2017 11
- 12. Learning More • Runspaces – Hey Scripting Guy! https://blogs.technet.microsoft.com/heyscriptingguy/ 2015/11/26/beginning-use-of-powershell-runspaces- part-1/ • Runspaces simplified as much as possible: https://blog.netnerds.net/2016/12/runspaces- simplified/ • Joe Prox’s PoshRSJob: https://github.com/proxb/PoshRSJob 1/18/2017 12
- 13. 1/18/2017 13 About me dfurgiuele@igsenergy.com @pittfurg http://www.port1433.com http://www.genesface.com Contact Info I’m a Senior SQL Server DBA at IGS Energy in Dublin, Ohio. I’ve been using SQL Server since SQL Server 2000 and I love it. I also enjoy DevOps, release management, and PowerShell.