JMX Profiling with VisualVM

[Tidsuo]

I have been try for the past two days to get VisualVM to connect and monitor the Java process within the Docker container. Any help or troubleshooting steps would be greatly appreciated!

Docker Compose

version: "3"

services:
gtnh:
  image: itzg/minecraft-server:java19
  container_name: gregtechNH
  hostname: gregtechNH
  env_file:
    - ./.env

  ports:
  - "25565:25565"
  - "7091:7091/tcp"

  environment:
    TZ: ${TZ}
    TYPE: FORGE
    VERSION: 1.7.10
    FORGE_VERSION: 10.13.4.1614
    JVM_OPTS: -Dfml.readTimeout=180 @java9args.txt
    GENERIC_PACK: http://downloads.gtnewhorizons.com/ServerPacks/GT_New_Horizons_2.3.0_Server_Java_17-19.zip
    MEMORY: 4G
    ENABLE_ROLLING_LOGS: true
    GUI: false
    LOG_TIMESTAMP: true
    
    OVERRIDE_SERVER_PROPERTIES: false
    SKIP_GENERIC_PACK_UPDATE_CHECK: true
    ENABLE_JMX: true
    JMX_HOST: 10.70.24.10
    
    EULA: "TRUE"
    
  volumes:
    - '/shares/games/gtnh230:/data'

  tty: true
  stdin_open: true
  restart: unless-stopped

In VisualVM I entered the same IP address appended with the port 7091 under the "Add JMX connection" option that I set for the JMX_HOST environment variable.

[itzg]

The JMX connectivity is very particular and I haven't tried it lately. The only concern I can see with what you're trying is that you didn't quote the "true" and "false" values. I'm surprised compose didn't give an error about schema validation.

[Tidsuo]

I've enclosed the true and false values in quotes but it doesn't seem to have done anything.

I will outline everything I did to attempt a connection:

1. Enable the JMX environment variables in the docker compose and set port 7091:7091
2. On the Windows machine open putty > connections > tunnel set source port to 7091 and destination localhost:7091
3. VisualVM: Local > Add JMX connection, enter localhost:7091

I did the above steps as well when JMX_HOST was set to the Docker Host IP address and used the Remote tab in VisualVM.

Both attempts did not work. I don't want to take up a lot of your time with this but could some pointers be provided as to what I should look at to provide more information about what is going on.

[itzg]

One thing you could try is setting JMX_HOST to "localhost". I seem to remember that it was more about it matching what the JMX console thinks it is connecting to.

Otherwise, I my only other advice is researching JMX remote connectivity in general. To help with that research, you can set DEBUG_EXEC to see exactly the command line that is used to kick off the Java process.