8000 Fix NullReferenceException in DSC ClearCache() by anmenaga · Pull Request #15373 · PowerShell/PowerShell · GitHub
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Fix NullReferenceException in DSC ClearCache() #15373

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Merged
merged 3 commits into from
May 12, 2021
Merged

Fix NullReferenceException in DSC ClearCache() #15373

merged 3 commits into from
May 12, 2021

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anmenaga
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@anmenaga anmenaga commented May 10, 2021 •
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PR Summary

In a multi-threaded environment there is a NullReferenceException in DSC ClearCache().
This fix is needed for GuestConfig.

PR Context

Initial values for fields marked with ThreadStaticAttribute should not be used, because such initialization occurs only once, when the class constructor executes, and therefore affects only one thread. Sometimes in a multi-threaded GuestConfig environment this was causing NullReferenceException in ClearCache() methods where the ThreadStatic filed t_currentImportDscResourceInvocations was accessed.

GuestConfig verified this fix on private binaries.

Side note: the entire section of code, where current fix is, will be removed soon by DSC as a subsystem PR.

PR Checklist

@anmenaga anmenaga added the CL-General Indicates that a PR should be marked as a general cmdlet change in the Change Log label May 10, 2021
@ghost ghost assigned iSazonov May 10, 2021
@daxian-dbw
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Good catch, @anmenaga! Quoted from docs:

Do not specify initial values for fields marked with ThreadStaticAttribute, because such initialization occurs only once, when the class constructor executes, and therefore affects only one thread. If you do not specify an initial value, you can rely on the field being initialized to its default value if it is a value type, or to null if it is a reference type.

@anmenaga
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This is needed for GC release in a couple of days, so merging.

@anmenaga anmenaga merged commit ae77246 into PowerShell:master May 12, 2021
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ghost commented May 27, 2021

🎉v7.2.0-preview.6 has been released which incorporates this pull request.:tada:

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@daxian-dbw daxian-dbw daxian-dbw approved these changes

@iSazonov iSazonov iSazonov approved these changes

@adityapatwardhan adityapatwardhan Awaiting requested review from adityapatwardhan

@SteveL-MSFT SteveL-MSFT Awaiting requested review from SteveL-MSFT

@TravisEz13 TravisEz13 Awaiting requested review from TravisEz13

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@iSazonov iSazonov

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