Workflow 1 - PowerShell script modifies the activities contained in the SR.
Workflow 2 - PowerShell script modifies the SR itself.
Intermittently, both workflows will fail. This appears to happen when both workflows execute concurrently.
Outputting the error from both we see:
__$error[0] | Format-List -Force | Out-String__
```
Exception : System.ArgumentException: Item has already been added. Key in dictionary: 'localhost' Key being added: 'localhost' at System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add) at SMLets.ConnectionHelper.GetMG(String computerName, PSCredential credential) in c:\Users\Administrator\Documents\WindowsPowerShell\CodePlex\smlets\Main\Source\SMLets\SMLets\Helper.cs:line 301 at SMLets.SMCmdletBase.BeginProcessing() in c:\Users\Administrator\Documents\WindowsPowerShell\CodePlex\smlets\Main\Source\SMLets\SMLets\Helper.cs:line 69
TargetObject : localhost
CategoryInfo : InvalidOperation: (localhost:String) [Get-SCSMClass], ArgumentException
FullyQualifiedErrorId : GenericMessage,SMLets.GetSMClassCommand
ErrorDetails :
InvocationInfo : System.Management.Automation.InvocationInfo
PipelineIterationInfo : {0, 0}
PSMessageDetails :
```
__$error[0].exception | format-list -force | Out-String__
```
Message : Item has already been added. Key in dictionary: 'localhost' Key being added: 'localhost'
ParamName :
Data : {}
InnerException :
TargetSite : Void Insert(System.Object, System.Object, Boolean)
StackTrace : at System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add) at SMLets.ConnectionHelper.GetMG(String computerName, PSCredential credential) in c:\Users\Administrator\Documents\WindowsPowerShell\CodePlex\smlets\Main\Source\SMLets\SMLets\Helper.cs:line 301 at SMLets.SMCmdletBase.BeginProcessing() in c:\Users\Administrator\Documents\WindowsPowerShell\CodePlex\smlets\Main\Source\SMLets\SMLets\Helper.cs:line 69
HelpLink :
Source : mscorlib
```
__$error[0].exception.stacktrace | Out-String__
```
at System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add)
at SMLets.ConnectionHelper.GetMG(String computerName, PSCredential credential) in c:\Users\Administrator\Documents\WindowsPowerShell\CodePlex\smlets\Main\Source\SMLets\SMLets\Helper.cs:line 301
at SMLets.SMCmdletBase.BeginProcessing() in c:\Users\Administrator\Documents\WindowsPowerShell\CodePlex\smlets\Main\Source\SMLets\SMLets\Helper.cs:line 69
```
Comments: ** Comment from web user: psikic **
After looking at the source code, I notice we have these lines:
if ( ! ht.ContainsKey(emg.ConnectionSettings.ServerName))
{
ht.Add(emg.ConnectionSettings.ServerName,emg);
}
I think SMLets was just never written to be explicitly thread-safe. I'm assuming what is happening is multiple runbooks are doing the "ContainsKey" check at the same time and then both proceeding to run the ht.Add. Sometimes one of the runbooks is able to do the Add and the other one gets this error. Sometimes both of them get the error. There could be locking added around this block of code to make the operation atomic, but there might be a better way to seperate the data structure so the multiple threads don't share it?