Application crashes when droplet CPU usage reaches 40%

[roeurbnavy]

I am using meteor version 2.7.1 and using mup to deploy to digital ocean. I bought a droplet with 8 core cpu and 16GB ram to deploy the application, but when deploying it to users, it crashes every time there are many users requesting the application. Every time it crashes, I check the cup droplet and container in docker, the cup droplet is up to 40%, the application is crashing, while the cup container in docker is 100%. Why is the cup droplet not up to 80% or 90%, why is the application crashing like this? What is the problem? Please help me solve this problem, thanks in advance 🙏 .

module.exports = {
  servers: {
    one: {
      host: 'xxx.xxx.xxx.xxx',
      username: 'root',
      password: 'server-password'
    },
  },

  app: {
    // TODO: change app name and path
    name: 'app',
    path: '../',
    volumes: {
      '/data/file_uploads': '/data/file_uploads',
    },

    servers: {
      one: {},
    },

    env: {
      // TODO: Change to your app's url
      ROOT_URL: 'http://xxx.xxx.xxx.xxx',
      MONGO_URL: 'mongodb://mongodb/dbName',
      MONGO_OPLOG_URL: 'mongodb://mongodb/local',
    },

    docker: {
      image: 'zodern/meteor:root',
      prepareBundle: true,
      useBuildKit: true,
    },
    deployCheckWaitTime: 120,
    enableUploadProgressBar: true,
  },

  mongo: {
    version: '5.0.5',
    servers: {
      one: {},
    },
  },
}

[zodern]

I'm not aware of an issue in Mup that would cause a container to crash when it uses 100% cpu. I have a few projects that use 100% cpu at times without issue.

It looks like Digital Ocean is showing cpu usage so 100% is using all cores at maximum, while other places might show it as 800% (using 8 cores at 100%). Node is mostly single threaded (additional threads can be used for some types of garbage collection or other things), so it should only account for ~15% of the cpu usage in Digital Ocean's graph.

Are you sure the container is crashing? Do the app's logs show it as starting again? You can also run mup meteor status on your computer, or run docker status <container name> on the server to check how many times it has crashed and restarted.

Do you use Monti APM or any other tools to monitor it?

[roeurbnavy]

I checked again, when the cup container reached 100%, the application did not crash, but it was very slow and took a long time to open.

[zodern]

You will want to find why your app using all of the cpu.

A few ways you can:

• Add Monti APM: https://docs.montiapm.com/academy/welcome. The free plan has a number of metrics that might help, but the paid plans also allow recording cpu profiles
• You can run mup meteor debug to connect your local Node dev tools to take a cpu profile. Though this might not work reliably anymore after some changes in Chrome's node dev tools.
• You can record a profile on the server, and then copy it locally to analyze it: https://docs.montiapm.com/record-cpu-profile#local-profiles. I think there are also a couple other packages to do this that upload the profile to s3.