Hang on startup when awaiting terminal PID

Working with current master, I’m getting an occasional (about 50% of the time) hang on startup in Windows PowerShell.

This is again mysterious like the last issue I opened:

However, there’s no dispose issue here.

Debugging the progress of this seems to interfere with the possibility of this deadlock occurring.

The log progresses to this point:

2020-02-24 13:57:16.584 -08:00 [DBG] Starting server, deregistering host logger and registering shutdown listener
2020-02-24 13:57:16.842 -08:00 [DBG] Creating LSP transport with endpoint InOut pipe: PSES_lffxipsq.u5q
2020-02-24 13:57:16.848 -08:00 [VRB] Writing session file
2020-02-24 13:57:16.848 -08:00 [VRB] Writing session started
2020-02-24 13:57:16.869 -08:00 [VRB] Assembly resolve event fired for Microsoft.WSMan.Management.resources, Version=3.0.0.0, Culture=en-US, PublicKeyToken=31bf3856ad364e35
2020-02-24 13:57:16.870 -08:00 [VRB] Assembly resolve event fired for Microsoft.WSMan.Management.resources, Version=3.0.0.0, Culture=en-US, PublicKeyToken=31bf3856ad364e35
2020-02-24 13:57:16.906 -08:00 [VRB] Loaded System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
2020-02-24 13:57:16.906 -08:00 [VRB] Loaded System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
2020-02-24 13:57:16.920 -08:00 [DBG] Session file written to c:\Users\roholt\Documents\Dev\vscode-PowerShell\sessions\PSES-VSCode-1088-643948 with content:
{"status":"started","languageServiceTransport":"NamedPipe","languageServicePipeName":"\\\\.\\pipe\\PSES_lffxipsq.u5q","debugServiceTransport":"NamedPipe","debugServicePipeName":"\\\\.\\pipe\\PSES_vtetuqus.ss5"}

[rjmholt]

Unfortunately there’s really not much to go on. When I next reproduce it I’ll take a full screenshot

[rjmholt]

Just to document a bit more, I can reproduce this with the following change from https://github.com/PowerShell/vscode-powershell/commit/d431617d6997c75fdce35342323e016f1bbaf271:

diff --git a/src/process.ts b/src/process.ts
index aa957b5..b70966e 100644
--- a/src/process.ts
+++ b/src/process.ts
@@ -128,7 +128,9 @@ export class PowerShellProcess {

         // Log that the PowerShell terminal process has been started
         this.log.write("Registering terminal PID log callback");
-        this.consoleTerminal.processId.then((pid) => this.logTerminalPid(pid, pwshName));
+        const pid = await this.consoleTerminal.processId;
+        this.logTerminalPid(pid, pwshName);
+        // this.consoleTerminal.processId.then((pid) => this.logTerminalPid(pid, pwshName));

         return sessionDetails;
     }

So startup pauses, since the client never opens a named pipe. The debugging the server shows it waiting on a named pipe connection.

In the client, pausing the debugger shows us stopped here:

For whatever reason we are left awaiting the processId value.

I’ve only seen reports of this on Windows.