memory-visualizer v1.0.4

Package for Node.js.

Table Of Contents

• Installation
• Examples
• Usage
• Tip
• Specs
• Important Notes
• Error Reporting

Installation

npm i --save-dev memory-visualizer

Examples

First example:
And the second example where user logs are stacked above the memory meter:

Usage

This is a simple library with which you can display memory usage in the termianl window. You can include it in your root file and either start it programatically with parameters or pass the parameters in the cli options and then trigger the toggle in the terminal with CTRL + S on your keyboard. Programatic usage:

const memoryVisualizer = require('memory-visualizer')
const stop = memoryVisualizer.start(13, 'rss')
setTimeout(() => stop(), 1e4) // Stop in 10 seconds.

Terminal usage (in my-root-file.js memory-visualizer must be included):

OR node my-root-file.js --memoryVisualizerFps=13 --memoryVisualizerMemoryName=rss
OR node my-root-file.js --memoryVisualizerFps=13
OR node my-root-file.js --memoryVisualizerMemoryName=rss

Tip

This utility may be useful, during the memory leak(s) detection process.

Tests

Works on the following Node.js versions: 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0, 12.7.0. Tested on the following OSs: Ubuntu 18.04.2 LTS, MacOS 10.11 "El Capitan" & Windows 10 Pro.

Specs

• {Function} start(fps, memoryName, memoryCapacityForDisplay): Function - starts the visualization process.
  • param {number} fps- (Frames Per Second) is the paramter which specifies how many times per second must the process reprint the memory usage. Defaults to 30. If a value type will not be a number it will throw a TypeError; Maximum threshold is 60, passing more then that will throw an Error.
  • param {string} memoryName - this can be set to rss, heapTotal, heapUsed or external (defaults to rss). Passing other value will throw an Error.
  • param {number} memoryCapacityForDisplay - after a lot of search, I wasn't able to find the default value of --max-old-space-size anywhere, so I set the approximation (1200 MB) based on my observations (but still - on different operating systems, when I tried to reach the maximum memory capacity it showed more less diferent results, so this value is not precise). Because of that you can set this value as a third parameter of start function and also you can pass it as a CLI option.
  • return {Function} stop(): void - this function is used to stop the printing process.

• CTRL + S - turns on and off the megabyte meter on both programtic stratup and by only requiring the package into the root file. When it is only included and not start()ed, it won't be shown by default.

• Starting using CLI node my-root-file.js
  • {number} --memoryVisualizerFps - same definition as start method's fps param.
  • {string} --memoryVisualizerMemoryName - same definition as start method's memoryName param.
  • {number} --memoryVisualizerMemoryCapacityForDisplay - same definition as start method's memoryCapacityForDisplay param.

Important Notes

• Node.js API returns used memory in bytes. Then it is converted to megabytes. Bytes are converted into megabytes not in mebibytes.
• Some terminals may not support ANSI colors, so the megabyte meter pipes will have white or the color you have set as a default option for the text.

Error Reporting

For any issue, feel free to create the GitHub issue.