Powershell endinvoke function gets stuck under heavy load

My application is written in c# and uses Powershell class of .net library. It is multi-threaded and can execute a bunch of powershell scripts simultaneously on a runspacepool. I use a runspacepool size of 100. Before the execution of each script I create a session to the target computer, by using the code below. I use BeginInvoke to start execution in a pipeline and end-invoke to get the results, which include the session.

ps = PowerShell.Create() var sessionScript = new PSCommand(); sessionScript.AddCommand(New-PSSession); sessionScript.AddParameter("ConnectionUri", "http://192.xxx.x.xxx:5985";); sessionScript.AddParameter("AllowRedirection"); var sessOpt = new System.Management.Automation.Remoting.PSSessionOption(); sessOpt.OpenTimeout = new TimeSpan(0,0,0,0, 120000); sessOpt.CancelTimeout = new TimeSpan(0, 0, 0, 0,120000); sessionScript.AddParameter("SessionOption", sessOpt); var cred = new PSCredential(uName, password); sessionScript.AddParameter("Credential", cred); ps.Commands = sessionScript ps.RunSpacePool = mypool ## size 100 created earlier asyncResult = ps.BeginInvoke(); resultsOut = ps.EndInvoke(asyncResult); All is fine when I keep my number of parallel executing sessions below 100. Once in a while when I hit 100 and above, I notice one or two threads (.net tasks) just getting stuck. I did some debugging and realized that the thread was getting stuck for EndInvoke. Even after a week the call just didn't return and the thread was still alive.

So, I replaced execution code by adding a Timer to this operation

Timer taskTimer = new Timer(TaskHitTimeout, null , 120000, System.Threading.Timeout.Infinite);
asyncResult = ps.BeginInvoke();
while (true)
if (asyncResult.IsCompleted || this.isCancelled)

if (!this.isCancelled)
     resultsOut = ps.EndInvoke(asyncResult);

and in the TimerHandler I set isCancelled to True

private void TaskHitTimeout(Object statusCode) { this.isCancelled = True;}

This did fix my problem. But I would like to understand why the call to EndInvoke just doesn’t return. Is there anything else I can do to improve this. And If anyone else has seen a similar issue.

Most of us here are using PowerShell itself, rather than coding in in C#, unfortunately. Sorry that we haven’t been able to help you to this point.