Child processes are not killed when stopping the debugger

[DonJayamanne]

Debug a python program that launches child processes.
Stop debugging, and confirm the child processes are killed.
This works in the old debugger, confirm this works as expected on the experimental debugger as well.

[DonJayamanne]

Flashing as a bug even though it hasn't been confirmed, hence the needs verification flag.
Either way, it needs to be verified as this need to be looked into.

[DonJayamanne]

• Confirmed
• Debug following code:

import subprocess

p = subprocess.Popen(['python', '-c', 'import time; time.sleep(10000)'])
print(p.pid)
p = subprocess.Popen(['python', '-c', 'import time; time.sleep(10000)'])
print(p.pid)
p = subprocess.Popen(['python', '-c', 'import time; time.sleep(10000)'])
print(p.pid)
p.wait()

• Stop the debugger
• The above processes are not killed.
  Code from old debugger https://github.com/Microsoft/vscode-python/blob/master/src/client/debugger/PythonProcess.ts#L69

[DonJayamanne]

Upstream bug microsoft/ptvsd#503

[hjalmarlucius]

Hi, I still have this issue. It does not occur for every file I run and am not sure how to trigger it but if I do heavy debugging using Pytorch and Visdom as main addins, I eventually run out of memory.

[bersbersbers]

@DonJayamanne microsoft/ptvsd#503 was fixed and closed in November, but I am still seeing this issue (on Windows).

Interestingly, the above-mentioned fix involves a couple of atexits, such as atexit.register(kill_subprocesses). I myself have noticed that a workaround for killing processes called by subprocess which I came up with, using atexit too, was completely ineffective in VS Code on Windows. In particular, what I have noticed was that atexit works fine when running Python code in a terminal and closing it with Ctrl-C; but apparently, this is not what VS Code (Python) does, as atexit is not triggered when stopping debugging. (I had found the code that kills the Python process, and I believe it involves taskkill - so I am not surprised atexit does not work. I have to take this back, that was in https://github.com/Microsoft/vscode/blob/master/src/vs/workbench/contrib/debug/node/debugAdapter.ts)

So would one solution on Windows be to send a Ctrl-C to the Python process instead of killing it, so that at least a user's workaround to end processes might work?

[gramster]

Closed on debugger side in March.