Terminate quarto preview programmatically

[iot49]

Description

I start quarto preview programmatically with Python's subprocess.Popen. How can I terminate the process?

Apparently quarto preview spans deno run with a pid that differs from the one returned by subprocess.Popen: killing that process does not stop the previewer.

As a work-around I am currently using grep to find the pid of the deno process. Is there a more elegant solution?

[cderv]

Can you share a reproducible example of your script ? How are you terminating process ?

I believe this Python question about managing subprocess. Without using Python closing ending quarto preview in Terminal does close everything.

I think subprocess has some argument like start_new_session and process_group which would allow you to group everything under one PID (or GID) and be sure to terminate all at once.

That is just some memory from what I may have done in the past. unsure if this will solve.

Having a reproducible example of your current scripting will help anyone help you here.

---

@gordonwoodhull as we discussed reviving the package: running quarto preview from python feels something we should make easier with the quarto package: https://github.com/quarto-dev/quarto-python

[iot49]

This works (sort of):

import subprocess

# start previewer
proc = subprocess.Popen("quarto preview ...")

# stop previewer (including deno child)
subprocess.run(f"pgrep -P {proc.pid} | xargs kill", shell=True)
proc.kill()

Unlike quarto preview, which apparently uses a lock file to determine if a process is running already and terminate it as necessary, this code does not. Resulting error trace:

Terminating existing preview server....DONE

ERROR: Requested port 3838 is already in use.

Stack trace:
    at resolvePreviewOptions (file:///Applications/quarto/bin/quarto.js:83817:19)
    at eventLoopTick (ext:core/01_core.js:168:9)
    at async serveProject (file:///Applications/quarto/bin/quarto.js:100090:12)
    at async Command.actionHandler (file:///Applications/quarto/bin/quarto.js:100815:9)
    at async Command.execute (file:///Applications/quarto/bin/quarto.js:8017:13)
    at async Command.parseCommand (file:///Applications/quarto/bin/quarto.js:7907:20)
    at async quarto (file:///Applications/quarto/bin/quarto.js:118224:9)
    at async file:///Applications/quarto/bin/quarto.js:118244:9
    at async mainRunner (file:///Applications/quarto/bin/quarto.js:118128:9)
    at async file:///Applications/quarto/bin/quarto.js:118235:5

Although quarto (I assume) reports terminating the existing server, it apparently does not.

A workaround would be to search for the process with ps and kill it if found. Pretty hacky.

[cderv]

Is there a reason not to use terminate() method ?
https://docs.python.org/fr/dev/library/subprocess.html#subprocess.Popen.terminate

[iot49]

Apparently there are issues with terminate for processes started with Popen and shell=True:

https://stackoverflow.com/questions/4084322/killing-a-process-created-with-pythons-subprocess-popen

Haven't looked into it yet, I agree the solution is not robust at all.