Hello, I'm calling a powershell script from C#. The script is pretty small and is "gps;$host.SetShouldExit(9)", which list process, and then send back an exit code to be captured by the PSHost object.

The problem I have is when the pipeline has been stopped and disposed, the output reader PSHost collection still seems to be written to, and is filling up. So when I try and copy it to my own output object, it craps out with a OutOfMemoryException when I try to iterate over it. Sometimes it will except with a Collection was modified message. Here is the code.

 private void ProcessAndExecuteBlock(ScriptBlock Block)
   {
       Collection<PSObject> PSCollection = new Collection<PSObject>();
       Collection<Object> PSErrorCollection = new Collection<Object>();
       Boolean Error = false;
       int ExitCode=0;

       //Send for exection. 
       ExecuteScript(Block.Script);

       // Process the waithandles. 
       while (PExecutor.PLine.PipelineStateInfo.State  == PipelineState.Running)
       {
           // Wait for either error or data waithandle. 
           switch (WaitHandle.WaitAny(PExecutor.Hand))
           {
               // Data
               case 0:
                   Collection<PSObject> data =   PExecutor.PLine.Output.NonBlockingRead();
                   if (data.Count  > 0)
                   {
                       for (int cnt = 0; cnt <= (data.Count-1); cnt++)
                       {
                           PSCollection.Add(data[cnt]); 
                       }
                   }

                   // Check to see if the pipeline has been closed. 
                   if (PExecutor.PLine.Output.EndOfPipeline)
                   { 
                       // Bring back the exit code. 
                       ExitCode = RHost.ExitCode; 
                   }
                   break;
               case 1:
                   Collection<object> Errordata = PExecutor.PLine.Error.NonBlockingRead();
                   if (Errordata.Count > 0)
                   {
                       Error = true;
                       for (int count = 0; count <= (Errordata.Count - 1); count++)
                       {
                           PSErrorCollection.Add(Errordata[count]);
                       }
                   }
                   break;
           }
       }

       PExecutor.Stop();

       // Create the Execution Return block
       ExecutionResults ER = new ExecutionResults(Block.RuleGuid,Block.SubRuleGuid, Block.MessageIdentfier);
       ER.ExitCode = ExitCode;

       // Add in the data results.
       lock (ReadSync)
       {
           if (PSCollection.Count > 0)
           {
               ER.DataAdd(PSCollection);
           }
       }

       // Add in the error data if any.
       if (Error)
       {
           if (PSErrorCollection.Count > 0)
           {
               ER.ErrorAdd(PSErrorCollection);
           }
           else
           {
               ER.InError = true;
           }
       }

       // We have finished, so enque the block back. 
       EnQueueOutput(ER);
   }

and this is the PipelineExecutor class which setups the pipeline for execution.

public class PipelineExecutor
{
    private Pipeline pipeline;
    private WaitHandle[] Handles;

    public Pipeline PLine
    {
        get { return pipeline; }
    }

    public WaitHandle[] Hand 
    {
        get { return Handles; }
    }

    public PipelineExecutor(Runspace runSpace, string command)
    {       
        pipeline = runSpace.CreatePipeline(command);
        Handles = new WaitHandle[2];
        Handles[0] = pipeline.Output.WaitHandle;
        Handles[1] = pipeline.Error.WaitHandle;
    }

    public void Start()
    {
        if (pipeline.PipelineStateInfo.State == PipelineState.NotStarted)
        {
            pipeline.Input.Close();
            pipeline.InvokeAsync();
        }
    }

    public void Stop()
    {
        pipeline.StopAsync();
    }
}

An this is the DataAdd method, where the exception arises.

    public void DataAdd(Collection<PSObject> Data)
    {
        foreach (PSObject Ps in Data)
        {
            Data.Add(Ps);
        }
    }

I put a for loop around the Data.Add, and the Collection filled up with 600k+ so feels like the gps command is still running, but why. Any ideas.

Thanks in advance.