I finally found a workaround to this problem. runspaces are not thread-safe so you have to run them out of process. You don't even have to use snapin like one guy mentions. Here's my solution in C#, you should be able to reference this to make modifications to your powershell script to create a runspace out of processes. See line: RunspaceFactory.CreateOutOfProcessRunspace()
public async Task TestPowercli(string name, string vcenterHost) {
if (string.IsNullOrWhiteSpace(name)) { return; }
if (string.IsNullOrWhiteSpace(vcenterHost)) { return; }
instanceName = name.Trim();
int timeoutMins = 5;
string script = @"c:\temp\testpowercli\testpowercli.ps1 " + instanceName + " " + vcenterHost + " -verbose";
PowerShellProcessInstance instance = new PowerShellProcessInstance(new Version(5, 0), null, null, false);
using (Runspace runspace = RunspaceFactory.CreateOutOfProcessRunspace(new TypeTable(new string[0]), instance)) {
PowerShell ps = PowerShell.Create();
runspace.Open();
ps.Runspace = runspace;
ps.AddScript(script);
outputCollection.DataAdded += outputCollection_DataAddedPowercli;
// the streams (Error, Debug, Progress, etc) are available on the PowerShell instance.
// we can review them during or after execution.
// we can also be notified when a new item is written to the stream (like this):
ps.Streams.Error.DataAdded += Error_DataAddedPowercli;
ps.Streams.Verbose.DataAdded += Verbose_DataAddedPowercli;
IAsyncResult result = ps.BeginInvoke<PSObject, PSObject>(null, outputCollection);
DateTime start = DateTime.Now;
while (result.IsCompleted == false) {
if ((DateTime.Now - start).TotalMinutes > timeoutMins) {
Clients.All.getPowercliMessage(instanceName, "ERROR: Time out exceeded after " + timeoutMins + " minutes");
break;
}
await Task.Delay(1000);
}
}
Clients.All.getPowercliMessage(instanceName, "Done");
}
