heimdalljs

What is heimdalljs?

HeimdallJS is a lightweight performance monitoring library for JavaScript applications. It allows developers to track and measure the performance of their code by creating performance metrics and visualizing them. This can be particularly useful for identifying bottlenecks and optimizing the performance of web applications.

What are heimdalljs's main functionalities?

Creating a Monitor

This feature allows you to create a performance monitor that tracks the execution time of a specific block of code. You start the monitor before the code block and stop it after the code block.

const heimdall = require('heimdalljs');
const monitor = heimdall.start('my-monitor');
// Your code here
monitor.stop();

Tracking Performance Metrics

This feature allows you to track specific performance metrics by starting and stopping named metrics. You can then retrieve and log the statistics for these metrics.

const heimdall = require('heimdalljs');
heimdall.start('my-metric');
// Your code here
heimdall.stop('my-metric');
const stats = heimdall.statsFor('my-metric');
console.log(stats);

Visualizing Performance Data

This feature allows you to visualize the performance data collected by HeimdallJS. You can convert the performance data into a JSON format and log it for further analysis.

const heimdall = require('heimdalljs');
const monitor = heimdall.start('my-monitor');
// Your code here
monitor.stop();
const tree = heimdall.toJSON();
console.log(JSON.stringify(tree, null, 2));

Other packages similar to heimdalljs

performance-now

The 'performance-now' package provides a high-resolution timer for measuring performance in JavaScript applications. It is simpler and more lightweight compared to HeimdallJS, focusing solely on providing precise timestamps.

statsd

The 'statsd' package is a network daemon that listens for statistics, like counters and timers, sent over UDP or TCP and sends aggregates to one or more pluggable backend services. It is more comprehensive and can be used for a broader range of performance monitoring tasks compared to HeimdallJS.

node-perf

The 'node-perf' package is a performance monitoring tool for Node.js applications. It provides similar functionality to HeimdallJS, such as tracking execution time and performance metrics, but is specifically designed for Node.js environments.

README

Example Usage

Simple

var heimdall = require('heimdall');

function BroccoliNodeSchema() {
  this.builds = 0;
}


heimdall.node('broccoli', function () {
  heimdall.node('node:babel', BroccoliNodeSchema, function (h) {
    h.builds++;

    heimdall.node('node:persistent-filter', BroccoliNodeSchema, function (h) {
      h.builds++;
    });

    heimdall.node('node:caching-writer', BroccoliNodeSchema, function (h) {
      h.builds++;
    });
  });
});

{
  "nodes": [{
    "id": 0,
    "name": "broccoli",
    "stats": {
      "cpu": {
        "self": 10,
      },
    },
    "children": {
      "start": [1],
      "end": [1],
    },
  }, {
    "id": 1,
    "name": "node:babel",
    "stats": {
      "builds": 1,
      "cpu": {
        "self": 20,
      },
    },
    "children": {
      "start": [2, 3],
      "end": [2, 3],
    },
  }, {
    "id": 2,
    "name": "node:persistent-filter",
    "stats": {
      "builds": 1,
      "cpu": {
        "self": 30,
      },
    },
  }, {
    "id": 3,
    "name": "node:caching-writer",
    "stats": {
      "builds": 1,
      "cpu": {
        "self": 40,
      },
    },
  }],
}

With Monitors

var heimdall = require('heimdall');
var fs = require('fs');

var origLstatSync = fs.lstatSync;
var origMkdirSync = fs.mkdirSync;

heimdall.registerMonitor('fs', function FSSchema() {
  this.lstatCount = 0;
  this.mkdirCount = 0;
});

fs.lstatSync = function () {
  heimdall.statsFor('fs').lstatCount++;
  return origLstatSync.apply(fs, arguments);
}

fs.mkdirSync = function () {
  heimdall.statsFor('fs').mkdirCount++;
  return origMkdirSync.apply(fs, arguments);
}


function BroccoliNodeSchema() {
  this.builds = 0;
}


heimdall.node('broccoli', function () {
  heimdall.node('node:babel', BroccoliNodeSchema, function (h) {
    h.builds++;

    heimdall.node('node:persistent-filter', BroccoliNodeSchema, function (h) {
      h.builds++;
      fs.mkdirSync('./tmp');
    });

    heimdall.node('node:caching-writer', BroccoliNodeSchema, function (h) {
      h.builds++;
      fs.lstatSync('./tmp');
    });
  });
});

{
  "nodes": [{
    "id": 0,
    "name": "broccoli",
    "stats": {
      "cpu": {
        "self": 10,
      },
      "fs": {
        lstatCount: 0,
        mkdirCount: 0,
      },
    },
    "children": {
      "start": [1],
      "end": [1],
    },
  }, {
    "id": 1,
    "name": "node:babel",
    "stats": {
      "builds": 1,
      "cpu": {
        "self": 20,
      },
      "fs": {
        lstatCount: 0,
        mkdirCount: 0,
      },
    },
    "children": {
      "start": [2, 3],
      "end": [2, 3],
    },
  }, {
    "id": 2,
    "name": "node:persistent-filter",
    "stats": {
      "builds": 1,
      "cpu": {
        "self": 30,
      },
      "fs": {
        lstatCount: 0,
        mkdirCount: 1,
      },
    },
  }, {
    "id": 3,
    "name": "node:caching-writer",
    "stats": {
      "builds": 1,
      "cpu": {
        "self": 40,
      },
      "fs": {
        lstatCount: 1,
        mkdirCount: 0,
      },
    },
  }],
}