helpServer.R processes leaking in code-server

[tjpalanca]

Also posted on the code-server repo in case the fix needs to be with them: coder/code-server#4580

Describe the bug

Orphaned helpServer.R processes are leaking when opening and closing multiple R terminals in code-server.

> ps aux | grep helpServer.R
  565 ?        S      0:00 /bin/sh -c /usr/local/bin/R --silent --slave --no-save --no-restore -f /home/tjpalanca/.local/share/code-server/extensions/ikuyadeu.r-2.3.4/R/help/helpServer.R
  566 ?        Sl     0:23 /usr/local/lib/R/bin/exec/R --no-save --no-restore --silent --slave --no-save --no-restore -f /home/tjpalanca/.local/share/code-server/extensions/ikuyadeu.r-2.3.4/R/help/helpServer.R
  723 ?        S      0:00 /bin/sh -c /usr/local/bin/R --silent --slave --no-save --no-restore -f /home/tjpalanca/.local/share/code-server/extensions/ikuyadeu.r-2.3.4/R/help/helpServer.R
  724 ?        Sl     0:22 /usr/local/lib/R/bin/exec/R --no-save --no-restore --silent --slave --no-save --no-restore -f /home/tjpalanca/.local/share/code-server/extensions/ikuyadeu.r-2.3.4/R/help/helpServer.R
 1464 ?        S      0:00 /bin/sh -c /usr/local/bin/R --silent --slave --no-save --no-restore -f /home/tjpalanca/.local/share/code-server/extensions/ikuyadeu.r-2.3.4/R/help/helpServer.R
 1465 ?        Sl     0:05 /usr/local/lib/R/bin/exec/R --no-save --no-restore --silent --slave --no-save --no-restore -f /home/tjpalanca/.local/share/code-server/extensions/ikuyadeu.r-2.3.4/R/help/helpServer.R

Inspecting the tree for one of the orphaned processes, it's clear that they are orphaned and no longer connected to the original code-server process.

> pstree -psa 566
s6-svscan,1 -t0 /var/run/s6/services
  └─sh,565 -c /usr/local/bin/R --silent --slave --no-save --no-restore -f /home/tjpalanca/.local/share/code-server/extensions/ikuyadeu.r-2.3.4/R/help/helpServer.R
      └─R,566 --no-save --no-restore --silent --slave --no-save --no-restore -f /home/tjpalanca/.local/share/code-server/extensions/ikuyadeu.r-2.3.4/R/help/helpServer.R
         ├─{R},574
         ├─{R},575
         └─{R},576

As opposed to a newly created R terminal:

> pstree -psa 2056
s6-svscan,1 -t0 /var/run/s6/services
  └─s6-supervise,414 vscode
      └─node,1672 /usr/lib/code-server --auth none --disable-telemetry --bind-addr 0.0.0.0:8788
          └─node,1706 /usr/lib/code-server --auth none --disable-telemetry --bind-addr 0.0.0.0:8788
              └─node,1724 /usr/lib/code-server/vendor/modules/code-oss-dev/out/vs/server/fork
                  └─node,1935 /usr/lib/code-server/vendor/modules/code-oss-dev/out/bootstrap-fork --type=extensionHost
                      └─sh,2055 -c /usr/local/bin/R --silent --slave --no-save --no-restore -f /home/tjpalanca/.local/share/code-server/extensions/ikuyadeu.r-2.3.4/R/help/helpServer.R
                          └─R,2056 --no-save --no-restore --silent --slave --no-save --no-restore -f /home/tjpalanca/.local/share/code-server/extensions/ikuyadeu.r-2.3.4/R/help/helpServer.R
                             ├─{R},2064
                             ├─{R},2065
                             └─{R},2066

To Reproduce

**This bug does not exist in local Visual Studio Code.

1. Use code-server 3.12.0, vscode-R version 2.3.4
2. Create an R terminal
3. Close the R terminal
4. Start another R terminal
5. helpServer.R instances will keep piling up even if the original extensionHost was already killed.

Do you want to fix by self? (We hope your help!)

Yes, but I'm not exactly sure how to fix this.

(If yes,) what kind of help do you want? (e.g. Which file should I fix, Survey (related documents)

Need help to determine what could be causing it, and implementation?

Expected behavior

1. Expect only one helpServer.R child process to persist for the whole session.

Screenshots
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Environment (please complete the following information):

• OS: Linux
• VSCode Version: code-server 3.12.0, vs code 1.60.0
• R Version: 4.1.2
• vscode-R version: 2.3.4

Additional context

I think it is because the child process is not killed when the extensionhost is killed? In regular vs code, there is only 1 extensionhost whereas code-server spawns new ones for different windows.

[renkun-ken]

Does the latest development build still has this problem? I thought this should be fixed via #893 unless it is a different issue.

[tjpalanca]

Gave it a check. Installed the development build, and then spun up multiple R sessions. There are still orphaned helpServer.R processes running under PID 1.

[tjpalanca]

Here's the workaround I have running in the background for now:

while true
do
    pkill --full --parent=1 helpServer\.R$
    pkill --full --parent=1 helpServer\.R$
    sleep 10
done

[renkun-ken]

@ManuelHentschel Do you have any idea why would opening new terminals have anything to do with starting help server? They should be independent to my knowledge.

[ManuelHentschel]

If the extension activation runs again for each new window/extensionHost, this would cause new help servers to start each time. However, they should be killed when the extension is deactivated, and not be orphaned. Maybe the treekill package does not work properly here?

[renkun-ken]

@ManuelHentschel I tried using cp.kill() and everything works nicely. Looks like treekill package does not work here.

[renkun-ken]

@tjpalanca Would you like to try the build from #912?

[tjpalanca]

Will give it a try today!

[renkun-ken]

The build actually is not really working as expected in Linux and macOS, buy only in debug mode. I'm trying to figure it out a way that works on all platforms.