Hosting powershell runspace in web application

Question

I'm writing a web service that executes powershell scripts (active directory, directory management, etc).

Right now, Runspace instance is created per web request. As Runspace initialization is time consuming operation, plus often I have to import modules, like ActiveDirectory, which are also slow operations.

In this blog post Managing Exchange 2007 Recipients with C# , the Runspace instance is kept in a static field.

I wander what if I keep Runspace instance in static field, would it be thread safe? Maybe there are other drawbacks of doing it this way?

Thanks

x0n · Accepted Answer · 2011-09-28 01:13:36Z

12

Runspaces are not thread-safe, nor can they guarantee that the scripts they are running are either.

I would suggest you create a RunspacePool and have your web service queue work to it. This is actually pretty easy to do. I blogged about it for v2 ctp3, but the API has not changed for RTM.

http://www.nivot.org/2009/01/22/CTP3TheRunspaceFactoryAndPowerShellAccelerators.aspx

update:

If you want to preload each runspace in the pool with one or more modules, use the RunspaceFactory.CreateRunspacePool(InitialSessionState) overload. To see how to create and initialize this, see:

http://www.nivot.org/2010/05/03/PowerShell20DeveloperEssentials1InitializingARunspaceWithAModule.aspx

Every time you create a PowerShell instance, assign the pool to its RunspacePool property.

edited Sep 28, 2011 at 1:13

user142162

answered Feb 11, 2011 at 15:28

x0n

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3 Comments

Misha N. Over a year ago

Aha, great! So I should create static field RunspacePool and then pass it to every Powershell instance executed in every web request. Is there a way to preload modules to Runspaces in the pool? Maybe I don't even need to do that?

Misha N. Over a year ago

tnx, x0n. I wish I could give you two upvotes to this answer :)

x0n Over a year ago

np - btw, I fixed a typo. you assign the pool the powershell's runspacepool property, not runspace (but you would have spotted that pretty quickly.)

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