Fastify under-pressure how to find out which routes are reasons

[meotimdihia]

Do we have a way to find out which routes are the problem?

fastify.register(underPressure, {
  maxEventLoopDelay: 1000,
  exposeStatusRoute: true,
  pressureHandler: (req, rep, type, value) => {
      if (type === underPressure.TYPE_HEAP_USED_BYTES) {
        fastify.log.warn(`too many heap bytes used: ${value}`)
      } else if (type === underPressure.TYPE_RSS_BYTES) {
        fastify.log.warn(`too many rss bytes used: ${value}`)
      } else if (type == underPressure.TYPE_EVENT_LOOP_DELAY) {
        fastify.log.warn(`reached max even loop delay: ${value}`)
        fastify.Sentry.captureMessage('reached max even loop delay');
      }

      rep.send('out of memory') // if you omit this line, the request will be handled normally
    }
  })

Please give me a tip/guide. I don't know how to do it.

[mcollina]

req should have all the information regarding the route. I'm a bit concerned about that Infinity, can you add a full reproduction?

[meotimdihia]

@mcollina thanks. This project's source code is big, I need to find out the reason first. I'll add a demo if I can reproduce it.

[meotimdihia]

@mcollina I still can't fix this problem. My server just used 33% CPU and 50% memory.

Do we have any way to utilize 100% CPU?

[mcollina]

I'm sorry but I don't understand the question. The full point of under-pressure is to prevent the server from overloading, keeping it responsive at all times.

The fact that your server "go" at 33% of CPU can mean all sorts of things. Usually you are exahusting some other limited resources, such as a connection pool or an OS buffer, or file descriptor limit.

If you remove under-pressure, could you get it to go 100%.