Immediately Output Runspace Results to the Pipeline

In my previous post, I presented the template I use anytime I need to add multithreading to my scripts.

Recently, I had a request to add multi-threading to Read-DbaBackupHeader. This was the first runspace in which I had to output the results from the runspace to the host — usually I just needed commands to run in the background, like with bulk-inserts to SQL Server.

So two interesting things came out of this particular change. First, I made use of the time that was spent waiting for runspaces to finish.

Now, I’m basically doing this

Ultimately, though, this is what I had to do to get the output right to screen.

Now, I came upon an issue with the $restore sometimes not returning anything. I’m not sure why; perhaps it has something to do with pooling. SQL Server didn’t return an error reading the backup header, it just returned nothing. To handle this issue, I basically restarted the runspace if the result came back as null. The code is here if you’d like to see how I handled it.

Copy/Pastable Code

I generally like to provide code that actually does something useful but in this case, it just complicated things. So this outputs text — but it does it directly to the pipeline without waiting until all runspaces have finished.

If you’d like to see this with a couple more comments, check out the gist.

Hmm, I wonder if this runspace will be easier for others to understand. Looks like I’ll be linking this blog post in my previous one. Hope this helped!

Chrissy is a PowerShell MVP who has worked in IT for nearly 20 years, and currently serves as a Sr. Database Engineer in Belgium. Always an avid scripter, she attended the Monad session at Microsoft’s Professional Developers Conference in Los Angeles back in 2005 and has worked and played with PowerShell ever since. Chrissy is currently pursuing an MS in Systems Engineering at Regis University and helps maintain in her spare time. She holds a number of certifications, including those relating to SQL Server, SuSE Linux, SharePoint and network security. She recently became co-lead of the SQL PASS PowerShell Virtual Chapter. You can follow her on Twitter at @cl.

Posted in PowerShell, SQL Server

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