Regression: build task does not appear to terminate until user hits return in terminal

[gwk]

• VSCode Version: Version 1.18.0-insider (1.18.0-insider) dcee220
• OS Version: macOS 10.13.2 beta 17C67b

Steps to Reproduce:

1. Create new project directory, with .vscode/tasks.json:

{
  "version": "2.0.0",
  "echoCommand": false,
  "type": "process",
  "presentation": {},
  "tasks": [
    {
      "label": "build",
      "command": "./build.sh",
      "args": ["${relativeFile}"],
      "group": {"kind": "build", "isDefault": true}
    }
  ]
}

2. Create build.sh with executable permissions and contents:

#!/bin/sh

echo $@
sleep 2
echo "DONE."

3. Run the build command on any file (running it on build.sh itself works fine).

The task will print done and presumably terminate. However the VSCode terminal window will not show it as terminated, and if I press the "build" keybinding again I get "The task 'typecheck-current (vscode-task-unterminated)' is already active. To terminate it use Terminate Task... from the Tasks menu." However if I press return in the integrated terminal then I will immediately get the expected "Terminal will be reused by tasks, press any key to close it."

If you remove the sleep 2 then the problem becomes very hard to reproduce. I have occasionally had difficulty reproducing it with the sleep, but by changing the sleep duration to a larger value I can usually trigger the bug. This makes me think that the problem is due to a change in the subprocess polling or something similar.

This regression occurred in the last few days. It is very annoying because now I have to click on the terminal and hit return after every type check.

Reproduces without extensions: Yes

[dbaeumer]

@Tyriar the task system doesn't do anything special here. I listen for corresponding events on the terminal. Does this ring a bell for you? Could there be a timing issue with listeners in the terminal so that the task runner never receives the event.

[dbaeumer]

@gwk when this happens are the corresponding processes still alive (e.g. the bash executing the build.sh). And the tasks.json file you are using looks a little wired as will since you are actually executing a shell command. It should look like this:

{
  "version": "2.0.0",
  "tasks": [
    {
      "label": "build",
	  "type": "shell",
      "command": "./build.sh ${relativeFile}",
      "group": {"kind": "build", "isDefault": true}
    }
  ]
}

[dbaeumer]

@Tyriar this sounds very similar to #32276 (comment). Can you please have a look?

[gwk]

@dbaeumer I just verified that the task process does terminate according to ps ax but the task window does not notice until I hit return.

[dbaeumer]

@gwk thanks for the info.

[floooh]

I'm running into exactly same problem since moving my build system wrapper over to Tasks 2.0, this is also on the current MacOS Beta (Windows works fine, Linux so far untested).

The tasks invoke a python script, but VSCode doesn't detect that the task has finished (ps aux shows no running python instances though). Only focusing the Terminal output panel and hitting a key (doesn't have to be Enter) finishes the task properly.

• This problem does not occur when using the old tasks (which didn't output to the Terminal panel, but the Output panel).
• On MacOS, the problem happens both in VSCode 1.18 and the 1.19 Insider Build.
• It happens both with "process" and "shell" tasks.
• The problem does not happen with very trivial tasks (like just running "echo Hello World").
• It always happens with python though, no matter how trivial the script or task description.
• The python version is the builtin 2.7.10 (if that matters)

Here's what I'm seeing when a task is done (at this point, no python process is running, but VSCode thinks the task is still running):

Then hitting a key, this message appears, only at this point, VSCode thinks the task has finished:

An example task (fips is the name of the python script, or on Windows fips.cmd a batch wrapper which calls the python script, calling the command as "python fips ..." doesn't make a difference):

  {
   "problemMatcher":[
    {
     "owner":"cpp",
     "pattern":{
      "severity":4,
      "column":3,
      "file":1,
      "regexp":"^(.*):(\\d+):(\\d+):\\s+(warning|error):\\s+(.*)$",
      "line":2,
      "message":5
     },
     "fileLocation":"absolute"
    }
   ],
   "group":"build",
   "windows":{
    "command":"fips make DDSCubeMap"
   },
   "type":"shell",
   "label":"DDSCubeMap",
   "command":"./fips make DDSCubeMap",
   "presentation":{
    "reveal":"always"
   }
  },

[floooh]

...PS: I also have the impression that I'm only seeing this problem since very recently, but I am not entirely sure.

May be it's related to the latest MacOS Beta? (I only updated about 2 days ago)

[dbaeumer]

The terminal system for some reason thinks the process didn't finish correctly. Not sure why hitting a key makes the terminal move to its final state.

@Tyriar The message Terminal will be reused by tasks, press any key to close it is printed by the terminal service (tasks set this as a onExit value). So the terminal system doesn't detect the exit correctly.

Can you please investigate and see why the terminal doesn't work as expected.

[floooh]

Btw, I just noticed that the official Microsoft C# extension has the same problem on MacOS with the automatically created tasks.json. When running a build with Cmd+Shift+B, VSCode does not detect that the build has finished until a key is pressed. This is on the latest MacOS beta (10.13.2 Beta 17C76a).

[chrmarti]

@dbaeumer I can't reproduce this with the tasks.jsons and build.sh provided and invoking it on Cmd+Shift+B. Is there anything in addition I need to do / set up?

[floooh]

@gwk and I are both on the MacOS 10.13.2 Beta, may be that's the culprit? Since it also happens with .NET Core development and the official C# plugin on the normal 1.18.0 VSCode version I would expect many more bug reports otherwise...

I just tested with Typescript and get the same behaviour, even without a task.json file (just a tsconfig.json). On Cmd+Shift+B I get the dropdown with tsc: build - tsconfig.json and tsc: watch - tsconfig.json.

I select "build", and only this line is printed in the terminal panel:

> Executing task: tsc -p "/Users/floh/projects/altai/tsconfig.json" <

Starting another build gives me the dropdown that the task is already active.

Pressing a key in the terminal panel prints this:

Terminal will be reused by tasks, press any key to close it.

...and the task is detected as finished only then.

[chrmarti]

Thanks, I can reproduce it on MacOS 10.13.2 Beta (17C76a).

In the failure case: node-pty is waiting for 'close' on the terminal object, but that only comes after a key press triggered an 'error' event on the socket.

• Waiting for 'close': https://github.com/Tyriar/node-pty/blob/master/src/unixTerminal.ts#L79
• Emitting it after pressing a key: https://github.com/Tyriar/node-pty/blob/master/src/unixTerminal.ts#L107

In the success case: node-pty also waits for 'close' at the same location and in this case that is triggered through the socket's 'close'.

• Socket's close: https://github.com/Tyriar/node-pty/blob/master/src/unixTerminal.ts#L142

Not sure what could cause this.

[dbaeumer]

@chrmarti thanks for the investigation. Given that this only happens on a Beta of the Mac OS I would not do anything for a recovery build given the above analysis.

[gwk]

Curious, have we verified that this does not happen anywhere except the recent betas? I don't have that ability at the moment.

[dbaeumer]

Yes, @chrmarti was not able to reproduce it on a non beta release but was on the beta 10.13.2. Since we only got reports on the Beta it is plausible to assume it doesn't exist on non beta version.

[gwk]

OK. Just checked and the problem remains for macOS beta 4 (17C79a).

[deisner]

I'm experiencing the same problem, macOS 10.13.2 (now released), VS Code 1.18.1.

[dbaeumer]

@Tyriar can you please have a look. @chrmarti did quite some investigation already

[SolanumVexus]

I can confirm and localize the issue to macOS 10.13.2. Upon installing that update I immediately began to experience this issue.

[Tyriar]

Aaaand I'm back! Starting to look into it now, I upgraded to 10.13.2 and can reproduce.

[ZZYSonny]

I got the same problem on 10.13.2.

[Tyriar]

While I can consistent repro in VS Code, I'm having a bit of trouble reproducing in just node-pty. I had it happening a few times in a row (socket not closing), but then it just started working consistently again 😕

[Tyriar]

Got debugging on the terminal process working, when the keystroke happens the socket is perfectly fine according to nodejs:

So far it looks like this is either an issue with NodeJS or macOS.

[Tyriar]

Here's the error when enter is pressed:

[Tyriar]

Here's a summary of what's happening. libuv fires this callback when the process has an exit code, the callback is set here. That callback is called onexit and looks like this:

https://github.com/chjj/pty.js/blob/fe63a412574f45ee6bb6d8fab4a5c102107b5201/lib/pty.js#L108-L117

The problem occurs because it goes into the !self._emittedClose condition as the socket isn't closed yet and waits for it to fire before proceeding with killing the terminal. The problem is, under the latest macOS this just doesn't fire sometimes. I haven't been able to nail down exactly when it happens as it seems very inconsistent.

It's also interesting to note that often (not always) when the socket is closed properly it will close before the onexit callback is called.

My proposed solution is to add a 1 second timeout for the close event to fire, if it doesn't happen then assume something at a lower level went wrong and proceed with killing the terminal.

[Tyriar]

As reported in #39883 it can also happen when running exit from your shell, at which point the terminal's title becomes "kernal_task":

[Tyriar]

Upstream issue: microsoft/node-pty#163
Upstream PR: microsoft/node-pty#164

[Tyriar]

Cherry picked to release/1.19

[dbaeumer]

@Tyriar thanks for looking into this!

[floooh]

The fix appears to work in the current insider build, many thanks :)

[sstaub]

Also for me. Thank's