Remoting: Wait-RemoteScriptSession throws exception when remote script is done

[GlennvG]

When using Wait-RemoteScriptSession it is polling the remote script every 5 seconds. But when the remote script is finished it throws an error that the script session cannot be found.

Code:

Wait-RemoteScriptSession -Session $session -Id $jobId -Delay 5 -Verbose

Logging:

2017-12-19T12:48:06.5154815Z VERBOSE: Polling job b7668a0c-421a-4703-b94a-e111af7e30c7. Status : Busy.
2017-12-19T12:48:11.5207123Z VERBOSE: Checking the Runspace for the variable id.
2017-12-19T12:49:20.6055452Z ##[error]The script session with Id 'b7668a0c-421a-4703-b94a-e111af7e30c7' cannot be found.
2017-12-19T12:49:20.6057975Z VERBOSE: Polling job . Status : .
2017-12-19T12:49:20.6059073Z VERBOSE: Finished polling job b7668a0c-421a-4703-b94a-e111af7e30c7.
2017-12-19T12:49:20.6061579Z VERBOSE: Checking the Runspace for the variable id.
2017-12-19T12:49:20.9194256Z Get-ScriptSession : The script session with Id 'b7668a0c-421a-4703-b94a-e111af7e30c7' cannot be found.
2017-12-19T12:49:20.9195444Z At line:2 char:36
2017-12-19T12:49:20.9195935Z + $backgroundScriptSession = Get-ScriptSession -Id $params.__using_id
2017-12-19T12:49:20.9196430Z + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2017-12-19T12:49:20.9196997Z + CategoryInfo : ResourceUnavailable: (b7668a0c-421a-4703-b94a-e111af7e30c7:String) [Get-ScriptSession],
2017-12-19T12:49:20.9197511Z ObjectNotFoundException
2017-12-19T12:49:20.9198138Z + FullyQualifiedErrorId : ScriptSessionNotFound,Cognifide.PowerShell.Commandlets.ScriptSessions.GetScriptSessionCo
2017-12-19T12:49:20.9198805Z mmand

[michaellwest]

Hi @GlennvG, what version of Sitecore, SPE, and the SPE Remoting module are you using?

[GlennvG]

Hi @michaellwest

Sitecore: 8.2.5
SPE: 4.7
Remoting: 4.7

[michaellwest]

Would it be possible to provide a sample script for me to test with? Otherwise can you provide details about what your script is doing?

If the application pool recycles then that may lead to the session disappearing.

[GlennvG]

This is the script, we are installing 2 tds packages with only items:

$jobId = Invoke-RemoteScript -Session $session -ScriptBlock { Install-UpdatePackage -Path "$Package1" -UpgradeAction Upgrade -InstallMode Install Install-UpdatePackage -Path "$Package2" -UpgradeAction Upgrade -InstallMode Install Publish-Item -Id {11111111-1111-1111-1111-111111111111} -Recurse -PublishMode Smart -Database master } -AsJob -Verbose

[BIGANDYT]

Hey did anyone find a workaround or fix for this?

[winklermat]

Hi @michaellwest

We are using the remoting feature to execute index rebuilds and migration scripts in our CI/CD pipeline.
We regulary encounter the following error - especially when executing long running scripts:

The script session with Id '{SOME-GUID-HERE}' cannot be found.
At C:\Windows\system32\WindowsPowerShell\v1.0\Modules\SPE\Wait-RemoteScriptSession.ps1:73 char:21

We set the Cognifide.PowerShell.PersistentSessionExpirationMinutes setting to 120 minutes but that didn't solve the problem completely. After some digging in the source code I found out, that the script session is stored in the HttpRuntimeCache.

Console/Cognifide.PowerShell/Commandlets/ScriptSessions/BaseScriptSessionCommand.cs

Line 39 in bf1e23d

$"The script session with Id '{sessionId}' cannot be found.",

Console/Cognifide.PowerShell/Core/Host/ScriptSessionManager.cs

Line 128 in 0f33533

HttpRuntime.Cache.Add(sessionKey, session, null, Cache.NoAbsoluteExpiration,

Although the cache is configured with NoAbsoluteExpiration, there is no guarantee that the cache can not be cleared while running a script in a remote session and therefore losing the remoting connection to the server. A reason can be low memory on the web server. See: https://social.msdn.microsoft.com/Forums/vstudio/en-US/e9c0d73f-f2e7-476d-9a78-d6f65501190a/httpruntime-cache-value-automatically-cleares?forum=wcf

Shouldn't the implementation be changed so that the script sessions are stored in a more persistent and reliable storage instead of using the HttpRuntimeCache?

We are using:

• Sitecore 8.2
• SPE 4.7

[AlexKasaku]

We should be able to address this by altering the CacheItemPriority to CacheItemPriority.NotRemovable, which will prevent items being cleared due to low memory. I think this should probably be configurable so it's a setting you would need to enable.

Whilst we could look at a different storage mechanism, the sessions would need to be serializable which is unlikely to be easily achievable.

@winklermat - Though any changes would go into the next release. I could provide you with a 4.7 build of a patched assembly with that change in for you to test with, if you like?

[winklermat]

@AlexKasaku: Yes, I would like to test the patched version :)

[AlexKasaku]

@winklermat - Please drop the following into your Sitecore instance, backing up the existing assembly first. Note this is for 4.7 only

https://www.dropbox.com/s/xirxy4k3uj2n31k/Cognifide.PowerShell.dll?dl=0

Let me know if that works. It doesn't require a configuration change, I've just made the change directly.

If you need any further assistance with getting this working, it's best to join the Sitecore Slack and message me on there or join #module-spe. You can register via https://sitecore.chat/

[AlexKasaku]

@winklermat - Any luck with this?

[winklermat]

@AlexKasaku: Thank you for the patch. I didn't have the time yet to test your change. I will post my feedback here as soon as we tested. I hope to be able to do it in our next sprint.

[winklermat]

@AlexKasaku: We applied the patch to our codebase and our nightly deployments are now running without any problems since one week :)
I think your change solved the problem with the failing remoting connection.
Thank you! 👍😁