Wrong pid on windows: Error: kill ESRCH

[coderaiser]

Every new started process gets wrong pid which is different from ones shown in task manager.
Could be reproduced with the demo of xterm.js.
Related to xterm.js issue.

> [email protected] start C:\Users\coderaiser\Documents\GitHub\xterm.js
> node demo/app

App listening to http://127.0.0.1:3000
Created terminal with PID: 928
Connected to terminal 928
internal/process.js:173
      throw errnoException(err, 'kill');
      ^

Error: kill ESRCH
    at exports._errnoException (util.js:1022:11)
    at process.kill (internal/process.js:173:13)
    at WebSocket.<anonymous> (C:\Users\coderaiser\Documents\GitHub\xterm.js\demo\app.js:72:13)
    at emitTwo (events.js:111:20)
    at WebSocket.emit (events.js:191:7)
    at WebSocket.cleanupWebsocketResources (C:\Users\coderaiser\Documents\GitHub\xterm.js\node_modules\ws\lib\WebSocket.js:950:8)
    at emitOne (events.js:101:20)
    at Socket.emit (events.js:188:7)
    at emitErrorNT (net.js:1281:8)
    at _combinedTickCallback (internal/process/next_tick.js:74:11)

npm ERR! Windows_NT 10.0.14393
npm ERR! argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "start"
npm ERR! node v7.2.0
npm ERR! npm  v3.10.9
npm ERR! code ELIFECYCLE
npm ERR! [email protected] start: `node demo/app`
npm ERR! Exit status 1

[Tyriar]

This is also probably the root cause of microsoft/vscode#14286

It's related to winpty, currently it's being set to (int)winpty_agent_process(pc) here, which points at the winpty agent process. Perhaps the handle is not being cast correctly?

[Tyriar]

@rprichard is there an easy way to get the winpty agent process ID from winpty_agent_process? I see it being set here but not sure if this is surfaced through the API?

[rprichard]

Yes, you'd call GetProcessId on the winpty_agent_process handle. Don't close the agent process handle afterwards -- libwinpty does that itself.

Do you want the PID of the winpty agent or the PID of the process running inside winpty (e.g. powershell.exe)? If you want the latter, then you need to get a process handle from winpty_spawn and pass that to GetProcessId.

The code is currently getting the spawned child process' handle and putting it into handle:

HANDLE handle = nullptr;
BOOL spawnSuccess = winpty_spawn(pc, config, &handle, nullptr, nullptr, nullptr);

The code doesn't do anything with handle, though. It doesn't even close the handle, so the handle is leaked (until the node process exits). (The PID is also leaked and can't be reused until the node process exits).

I'd guess you actually want to use GetProcessId(handle), then call CloseHandle on the spawned handle when the pty object is cleaned up.

Alternatively, if you really do want the agent PID, then you can fix the handle leak by passing nullptr to winpty_spawn:

BOOL spawnSuccess = winpty_spawn(pc, config, nullptr, nullptr, nullptr, nullptr);

[Tyriar]

Thanks @rprichard, I do want the inner process from winpty_spawn (powershell).

[Tyriar]

Managed to get this working pretty easily thanks to your help @rprichard 👍