VSCode leaves several running processes after exit

Issue Type: Bug

Steps to reproduce:

1. Launch vscode.
2. Open or create a Jupyter Notebook.
3. Do some work on it.
4. Close vscode.
5. Optional: Rinse and repeat.

Expected behavior:

Any processes started by vscode are closed.

Actual behavior:

After launching and closing vscode a few times (and realizing I am starting to run out of memory) I notice this:

user@laptop:~$ ps aux | grep -v networkd-dispatcher | grep -v unattended | grep -v grep | grep python
user   344513  0.2  0.6 4115828 102040 ?      Sl   May19   3:19 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   345452  0.4  5.3 5162548 858400 ?      Sl   May19   5:46 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   345607  0.2  0.6 4443632 102484 ?      Sl   May19   3:01 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   353204  0.2  0.6 3788220 105468 ?      Sl   May19   1:55 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   353605  0.0  0.2 117072 46508 ?        S    May19   0:01 /usr/bin/python3 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/pythonFiles/pyvsc-run-isolated.py vscode_datascience_helpers.daemon --daemon-module=vscode_datascience_helpers.jupyter_daemon -v
user   353771  0.3  0.6 3796468 105576 ?      Sl   May19   2:29 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   353933  0.2  0.2 3722708 39000 ?       Sl   May19   1:31 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   354840  0.2  0.2 3796424 35728 ?       Sl   00:35   1:34 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   355331  0.9  5.4 6179224 869260 ?      Sl   00:39   6:06 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   356104  0.3  0.6 3862044 111216 ?      Sl   00:52   1:52 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   366116  1.6  0.4 3796252 76032 ?       Sl   10:27   0:35 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   366803  2.3  0.4 1007044 69596 ?       Sl   10:32   0:44 /usr/bin/python3 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/pythonFiles/pyvsc-run-isolated.py vscode_datascience_helpers.daemon --daemon-module=vscode_datascience_helpers.jupyter_daemon -v
user   366808 10.1  5.4 5509256 871684 ?      Sl   10:32   3:16 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/languageServer.0.5.50/Microsoft.Python.LanguageServer
user   366831  0.0  0.2 551048 35328 ?        Ssl  10:32   0:01 /usr/bin/python3 -m ipykernel_launcher -f /home/user/.local/share/jupyter/runtime/kernel-33b1ca6c-b09c-41dd-b2fc-c466b2511581.json
user   366855  0.0  0.2 550640 35408 ?        Ssl  10:32   0:01 /usr/bin/python3 -m ipykernel_launcher -f /home/user/.local/share/jupyter/runtime/kernel-a5a7d55e-0ebc-4b4b-aac4-4d1dddff8450.json
user   368190  7.6  1.2 2471816 200372 ?      Ssl  10:45   1:27 /usr/bin/python3 -m ipykernel_launcher -f /home/user/.local/share/jupyter/runtime/kernel-b00685be-189e-4f07-80e0-237ab6772827.json
user   368212  0.0  0.2 550648 43728 ?        Ssl  10:45   0:00 /usr/bin/python3 -m ipykernel_launcher -f /home/user/.local/share/jupyter/runtime/kernel-918a11e0-f81e-4740-a3c1-e5d5ca074570.json
user   369055  4.4  1.3 2076996 219232 pts/0  Sl+  10:57   0:19 /usr/bin/python3 /home/user/.local/bin/ipython
user   369168  2.0  0.3 709300 62112 ?        Sl   10:58   0:08 /usr/bin/python3 /home/user/.vscode-oss/extensions/ms-python.python-2020.5.80290/pythonFiles/pyvsc-run-isolated.py vscode_datascience_helpers.daemon --daemon-module=vscode_datascience_helpers.jupyter_daemon -v
user@laptop:~$ 

Extension version: 2020.5.80290 VS Code version: Code - OSS 1.46.0 (3984852b33bd6897dd83108ac305c567d49e8fda, 2020-05-15T14:46:12.527Z) OS version: Linux x64 5.4.0-29-generic

System Info

Item	Value
CPUs	Intel® Core™ i7-1065G7 CPU @ 1.30GHz (8 x 1137)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: disabled_software skia_renderer: disabled_off_ok video_decode: unavailable_off viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off_ok webgl: enabled webgl2: enabled
Load (avg)	1, 2, 2
Memory (System)	15.23GB (0.93GB free)
Process Argv	–no-sandbox --unity-launch
Screen Reader	no
VM	0%
DESKTOP_SESSION	ubuntu
XDG_CURRENT_DESKTOP	Unity
XDG_SESSION_DESKTOP	ubuntu
XDG_SESSION_TYPE	x11

[rchiodo]

Perhaps if we change the daemon to start as a process group, it should kill the child process automatically.

[rchiodo]

The root cause of this bug is the daemon’s we spin up to make kernel’s launch faster.

I believe you can workaround the problem by eliminating these files here (copy them elsewhere first in case that breaks something else):

<extension dir>/pythonFiles/lib/python/pyls_jsonrpc