lsp-devtools inspect hangs upon quiting

[castedo]

VERSION 0.3

REPO STEPS:

• start lsp-devtools inspect
• quit, either by CTRL-Q or clicking "palette" and then "Quit"
• wait a few seconds or 5 minutes
• CTRL-C (twice if you don't wait 5 minutes)

RESULT
Hanging program, if you wait 5 minutes then:

/usr/lib64/python3.14/asyncio/events.py:94: RuntimeWarning: The executor did not finishing joining its threads within 300 seconds.

or if you hit CTRL-C earlier then:

^CTraceback (most recent call last):
  File "/usr/local/bin/lsp-devtools", line 8, in <module>
    sys.exit(main())
             ~~~~^^
  File "/usr/local/lib/python3.14/site-packages/lsp_devtools/cli/__init__.py", line 65, in main
    return parsed_args.run(parsed_args, extra)
           ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.14/site-packages/lsp_devtools/cli/inspector.py", line 98, in inspector
    app.run()
    ~~~~~~~^^
  File "/usr/local/lib/python3.14/site-packages/textual/app.py", line 2277, in run
    return asyncio.run(run_app())
           ~~~~~~~~~~~^^^^^^^^^^^
  File "/usr/lib64/python3.14/asyncio/runners.py", line 203, in run
    with Runner(debug=debug, loop_factory=loop_factory) as runner:
         ~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.14/asyncio/runners.py", line 63, in __exit__
    self.close()
    ~~~~~~~~~~^^
  File "/usr/lib64/python3.14/asyncio/runners.py", line 73, in close
    loop.run_until_complete(
    ~~~~~~~~~~~~~~~~~~~~~~~^
        loop.shutdown_default_executor(constants.THREAD_JOIN_TIMEOUT))
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.14/asyncio/base_events.py", line 706, in run_until_complete
    self.run_forever()
    ~~~~~~~~~~~~~~~~^^
  File "/usr/lib64/python3.14/asyncio/base_events.py", line 677, in run_forever
    self._run_once()
    ~~~~~~~~~~~~~~^^
  File "/usr/lib64/python3.14/asyncio/base_events.py", line 2008, in _run_once
    event_list = self._selector.select(timeout)
  File "/usr/lib64/python3.14/selectors.py", line 452, in select
    fd_event_list = self._selector.poll(timeout, max_ev)

and for the final CTRL+C:

^CException ignored on threading shutdown:
Traceback (most recent call last):
  File "/usr/lib64/python3.14/threading.py", line 1576, in _shutdown
    atexit_call()
  File "/usr/lib64/python3.14/threading.py", line 1547, in <lambda>
    _threading_atexits.append(lambda: func(*arg, **kwargs))
  File "/usr/lib64/python3.14/concurrent/futures/thread.py", line 31, in _python_exit
    t.join()
  File "/usr/lib64/python3.14/threading.py", line 1132, in join
    self._os_thread_handle.join(timeout)
KeyboardInterrupt: 

[alcarney]

Thanks, I think this is similar to #131, I haven't yet managed to figure out how to get these commands to exit cleanly :/
Especially if there is an active connection to a server.

[castedo]

Note: the above is without starting any lsp-devtools agent session.

Likely useful observation: if I

1. start both an lsp-devtools agent session and lsp-devtools inspect in any order, let them connect,
2. quit lsp-devtools inspect

Then lsp-devtools inspect will "wait" (cough, hangs 😉) until the lsp-devtools agent session ends, but otherwise exit gracefully.

[castedo]

But if the lsp-devtools agent session ends first, then lsp-devtools inspect will hang and need a CTRL-C.

[castedo]

I haven't yet managed to figure out how to get these commands to exit cleanly :/
Especially if there is an active connection to a server.

The following approach of reading stdio not the main thread is going to cause headaches (maybe not this one).

lsp-devtools/lib/lsp-devtools/lsp_devtools/agent/io_.py

Line 32 in a22568f

class StdinAsyncReader:

I can recommend running the read loop on stdin in the main thread and then run you main async loop in a separate thread like this:
https://gitlab.com/castedo/leanylsp/-/blob/8d3de885db2460c4ccf064b72c1c88815d81cd55/leanylsp.py#L347
and
https://gitlab.com/castedo/leanylsp/-/blob/8d3de885db2460c4ccf064b72c1c88815d81cd55/leanylsp.py#L319

This way hitting CTRL-C will interrupt just the main thread where blocking stdio IO is blocking and free it with a KeyboardInterupt out the stdin loop. The async loop will be unaffected and "safe".

[alcarney]

Note: the above is without starting any lsp-devtools agent session.

Thanks, I'd skipped over that detail.

The textual docs suggest that as long as you use async you don't need a separate thread. Since the agent communication is done over asyncio, I removed the background thread in the lsp-devtools inspect command (#230) which appears to fix it for me.

Could you try it and see if it also works for you?
Not sure if you use uv but this command should allow you to try it straight from my branch

uvx --with git+https://github.com/alcarney/lsp-devtools/@push-nysnlvrvtzks#subdirectory=lib/lsp-devtools lsp-devtools inspect

[castedo]

Nice! That branch fixes the hang on quit. (I installed it in a new container).

[alcarney]

Glad to hear it, I'll merge #230 then :)