Bug : Leftover Child Processes

[NaiveInvestigator]

Whenever after watching a vid, some child processes are always left around, tho i don't know why.

This is a big problem for me as like it interferes with other scripts i have. Sorry for disturbing again :<

[husudosu]

No worries.
I'll look into it.

[husudosu]

I've checked on Windows machine and it seems MPV launches only "Node.JS" and "Console Windows Host" that should be expected. Node.JS runs the Remote server and Console Windows Host runs the console process for Node JS.
What other plugins not working? Maybe there's a port, socket issue.

[NaiveInvestigator]

I've checked on Windows machine and it seems MPV launches only "Node.JS" and "Console Windows Host" that should be expected. Node.JS runs the Remote server and Console Windows Host runs the console process for Node JS. What other plugins not working? Maybe there's a port, socket issue.

Not that one there should be other mpv processes open too but with a different PID. Easiest way to find that is to close mpv then search for the child process. If it doesn't show up at your machine then probably there is something weird on my enviroment then. If that was the case, sorry for bother you. But this doesn't happen tho if i don't run the server script.

[AgentConDier]

This occasionally happens on my linux machine as well. I haven't been able to track down the exact circumstances yet. There shouldn't be any MPV instances open right now, but some are showing up in the task manager:

system info

mpv-remote-node version is git commit 1209b0a

$ mpv -v
[cplayer] Command line options: '-v'
[cplayer] mpv 0.35.1 Copyright © 2000-2023 mpv/MPlayer/mplayer2 projects
[cplayer]  built on UNKNOWN
[cplayer] FFmpeg library versions:
[cplayer]    libavutil       57.28.100
[cplayer]    libavcodec      59.37.100
[cplayer]    libavformat     59.27.100
[cplayer]    libswscale      6.7.100
[cplayer]    libavfilter     8.44.100
[cplayer]    libswresample   4.7.100
[cplayer] FFmpeg version: 5.1.4-0+deb12u1
[cplayer] 
[cplayer] Configuration: meson configure build -Dprefix=/usr -Dbuildtype=plain -Doptimization=plain
[cplayer] List of enabled features: alsa av-channel-layout caca cdda cplayer cplugins cuda-hwaccel cuda-interop dmabuf-interop-gl dmabuf-interop-pl dmabuf-wayland drm drm-is-kms dvbin dvdnav egl egl-drm egl-helpers egl-x11 ffmpeg ffnvcodec gbm gl gl-wayland glibc-thread-name glob glob-posix gpl iconv jack javascript jpeg jpegxl lcms2 libarchive libass libavdevice libbluray libdl libm libmpv-shared libplacebo libplacebo-next librt linux-fstatfs lua52 manpage-build memfd_create noexecstack pipewire plain-gl posix pulse rubberband rubberband-3 sdl2 sdl2-audio sdl2-gamepad sdl2-video sixel spirv-cross stdatomic threads uchardet vaapi vaapi-drm vaapi-egl vaapi-libplacebo vaapi-wayland vaapi-x-egl vaapi-x11 vdpau vector vt.h vulkan wayland wayland_protocols_1_24 x11 xv zimg zlib
[cplayer] Reading config file /etc/mpv/encoding-profiles.conf
[cplayer] Applying profile 'default'...
[cplayer] Reading config file /home/me/.config/mpv/mpv.conf
[cplayer] Applying profile 'default'...
[cplayer] Setting option 'slang' = 'jpn,eng' (flags = 4)
[cplayer] Setting option 'alang' = 'jpn,ger,eng' (flags = 4)
[cplayer] Setting option 'save-position-on-quit' = '' (flags = 4)
[cplayer] Setting option 'ignore-path-in-watch-later-config' = '' (flags = 4)
[cplayer] Setting option 'write-filename-in-watch-later-config' = '' (flags = 4)
[cplayer] Setting option 'sub-file-paths' = '/home/me/Downloads' (flags = 4)
[cplayer] Setting option 'screen' = '0' (flags = 4)
[cplayer] Setting option 'v' = '' (flags = 8)
[ifo_dvdnav] Opening /home/me/.config/mpv/input.conf
[bdmv/bluray] Opening /home/me/.config/mpv/input.conf
[file] Opening /home/me/.config/mpv/input.conf
[input] Parsing input config file /home/me/.config/mpv/input.conf
[input] Input config file /home/me/.config/mpv/input.conf parsed: 1 binds
[cplayer] mpv 0.35.1 Copyright © 2000-2023 mpv/MPlayer/mplayer2 projects
[cplayer]  built on UNKNOWN
[cplayer] FFmpeg library versions:
[cplayer]    libavutil       57.28.100
[cplayer]    libavcodec      59.37.100
[cplayer]    libavformat     59.27.100
[cplayer]    libswscale      6.7.100
[cplayer]    libavfilter     8.44.100
[cplayer]    libswresample   4.7.100
[cplayer] FFmpeg version: 5.1.4-0+deb12u1
[cplayer] 
[cplayer] Usage:   mpv [options] [url|path/]filename
[cplayer] 
[cplayer] Basic options:
[cplayer]  --start=<time>    seek to given (percent, seconds, or hh:mm:ss) position
[cplayer]  --no-audio        do not play sound
[cplayer]  --no-video        do not play video
[cplayer]  --fs              fullscreen playback
[cplayer]  --sub-file=<file> specify subtitle file to use
[cplayer]  --playlist=<file> specify playlist file
[cplayer] 
[cplayer]  --list-options    list all mpv options
[cplayer]  --h=<string>      print options which contain the given string in their name
[cplayer] 
[auto_profiles] Re-evaluating auto profile livestream 
[auto_profiles] Profile condition did not return a boolean, but nil. 
[cplayer] Set property: shared-script-properties -> 1
[cplayer] Set property: shared-script-properties -> 1
[cplayer] Set property: shared-script-properties -> 1

$ node -v
v18.19.0

$ npm -v
9.2.0

$ uname -a
Linux 6.6.9-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.6.9-1~mx23ahs (2024-01-02) x86_64 GNU/Linux

[WhoMI7]

Same issue here for for a long time

[AgentConDier]

I finally tracked down the cause for this. As far as I can tell, there is a race condition where remoteServer.js is started before the parent MPV process is ready to accept IPC connections.
The code in node_modules/node-mpv/lib/mpv/_startStop.js, called by

mpv-remote-node/remoteServer.js

Line 841 in 31dd6b5

await mpv.start();

will start a new MPV instance with the arguments we observed when there is any error communicating with the provided IPC socket.
I added a delay to try and fix this, but maybe a more elegant solution exists.

[stax76]

I struggled a lot with this bug, thanks @AgentConDier to find something that works.

function sleep(ms) {
  return new Promise((resolve) => {
    setTimeout(resolve, ms);
  });
}

async function main() {
  try {
    // Creates/clears file local options file.
    await sleep(2000);
    await mpv.start();

    // Create file-local-options if not exists.
    if (!fs.existsSync(FILE_LOCAL_OPTIONS_PATH)) writeFileLocalOptions({});
    if (settings.uselocaldb) await initDB();

    await showOSDMessage(
      `Remote access on: ${settings.serverIP}:${settings.serverPort}`,
      5000
    );
  } catch (error) {
    // handle errors here
    console.log(error);
  }
}