Helper to record node CPU profiles, which can be easily viewed as CPU flame graphs using Chrome debugger

cpu-profile-trigger.js

// Helper to record CPU profiles
// https://github.com/node-inspector/v8-profiler#cpu-profile-api
//
// Usage:
//   1. npm install v8-profiler
//   2. require('./cpu-profile-trigger') once in your app code
//   3. Start CPU profiling with kill -PIPE <pid>. Instructions will be logged to stdout.
//   4. Stop CPU profiling with running again kill -PIPE <pid>
//   5. Go to Chrome debugger, open Profiles tab. Click Load and 
//      open the <timestamp>.cpuprofile. It was saved to the same dir
//      where you started your app.
//   6. Open the CPU profile. You might want to change the view to "Chart". 
//      Default view is usually "Heavy (Bottom Up)" or "Tree (Top Down)".


var fs = require('fs');
var profiler = require('v8-profiler');

console.log('\n\n-----------------------------------------------------------');
console.log('CPU PROFILE RECORD TRIGGER LISTENING ..\n');
console.log('\nStart profiling with "kill -PIPE ' + process.pid + '"');
console.log('Stop profiling with the same command.');
console.log('-----------------------------------------------------------\n\n');

var callCount = 0;
process.on('SIGPIPE', function() {
  console.log('Received SIGPIPE signal.');

  var startTimestamp = timestamp();
  if (callCount % 2 === 0) {
    console.log('Start profiling ..');
    profiler.startProfiling(startTimestamp, true);
  } else {
    console.log('Stop profiling ..');
    var profile1 = profiler.stopProfiling();
    profile1.export(function(error, result) {
      const fileName = startTimestamp + '.cpuprofile';
      fs.writeFileSync(fileName, result);
      console.log('Saved CPU profile as ' + fileName);
      profile1.delete();
    });
  }

  ++callCount;
});

function timestamp() {
  return (new Date()).toISOString().split('.')[0].replace(/:/g, '-');
}