Profile node code

profile-node-code.js

// source: https://developer.ibm.com/node/2016/01/06/tips-optimizing-slow-code-in-nodejs/
// the resulting logfile can be imported into google chrome's JavaScript profiler (which seems
// to be deprecated???)

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

let  profilerRunning = false;

function toggleProfiling () {
    if (profilerRunning) {
        const profile = profiler.stopProfiling();

        // console.log('stopped profiling');
        profile.export()
            .pipe(fs.createWriteStream(`./myapp-${Date.now()}.cpuprofile`))
            .once('error',  profiler.deleteAllProfiles)
            .once('finish', profiler.deleteAllProfiles);
        profilerRunning = false;
        return;
    }
    profiler.startProfiling();
    profilerRunning = true;
    // console.log('started profiling');
}