@openprofiling/trigger-signal

OpenProfiling NodeJS - Signal Trigger

This trigger is most probably the easier to use because you just need to send a signal to the process (which is generally straightforward even with containers).

Advantages

• No specific setup, one CLI command away

Drawbacks

• Limited list of signal to listen on (see official doc)
  • I advise to use the SIGUSR1 and SIGUSR2 signal since they are reserved for user-space behavior.
• Behavior on Windows might be a little more complicated since there a no concept of signals on it (see official doc at the end of the previous link)

How to use

In the following example, when the profile will be done it will be written on disk:

import { ProfilingAgent } from '@openprofiling/nodejs'
import { FileExporter } from '@openprofiling/exporter-file'
import { InspectorCPUProfiler } from '@openprofiling/inspector-cpu-profiler'
import { SignalTrigger } from '@openprofiling/trigger-signal'

const profilingAgent = new ProfilingAgent()
// you just need to precise which signal the trigger need to listen
// little advise: only use SIGUSR1 or SIGUSR2
profilingAgent.register(new SignalTrigger({ signal: 'SIGUSR2' }), new InspectorCPUProfiler())
profilingAgent.start({ exporter: new FileExporter() })

Then to initiate the trigger, just send a signal to the desirated process:

linux/macos:

kill -s USR1 <pid>

You can find the PID via htop, ps aux or just log your process pid with console.log('Process pid is ' + process.pid)` when your application start.