Node.js v8.getHeapSpaceStatistics() Method

The v8.getHeapSpaceStatistics() method is an inbuilt application programming interface of the v8 module which is used to get statistics about heap space derived from the v8 version.

Syntax:

v8.getHeapSpaceStatistics();

Parameters: This method does not have any parameters.

Return Value: This method returns an object that contains statistics about version 8 heap space. The returned object usually contains an array of multiple elements, where each element consists of following fields:

• space_name: A string represents the name of the heap space.
• space_size: A number represents the heap space size.
• space_used_size: A number represents used heap space size.
• space_available_size: A number, represents available heap space size.
• physical_space_size: A number, specifying physical heap space size.

Below examples illustrate the use of v8.getHeapSpaceStatistics() method in Node.js.

Example 1: Filename: index.js

// Accessing v8 module
const v8 = require('v8');

// Calling v8.getHeapSpaceStatistics()
console.log(v8.getHeapSpaceStatistics());

Run index.js file using the following command:

node index.js

Output:

[ { space_name: 'read_only_space',
    space_size: 524288,
    space_used_size: 35208,
    space_available_size: 480376,
    physical_space_size: 524288 },
  { space_name: 'new_space',
    space_size: 2097152,
    space_used_size: 975376,
    space_available_size: 55792,
    physical_space_size: 2097152 },
  { space_name: 'old_space',
    space_size: 2330624,
    space_used_size: 2272448,
    space_available_size: 184,
    physical_space_size: 2330624 },
  { space_name: 'code_space',
    space_size: 1048576,
    space_used_size: 571968,
    space_available_size: 0,
    physical_space_size: 1048576 },
  { space_name: 'map_space',
    space_size: 536576,
    space_used_size: 344784,
    space_available_size: 0,
    physical_space_size: 536576 },
  { space_name: 'large_object_space',
    space_size: 0,
    space_used_size: 0,
    space_available_size: 1520180736,
    physical_space_size: 0 } ]

Example 2: Filename: index.js

// Accessing v8 module
const v8 = require('v8');

// Calling v8.getHeapSpaceStatistics()
stats = v8.getHeapSpaceStatistics();

var myList = []
for (var i = 0; i < stats.length; i++){
  var element = stats[i];

  myList.push({ "Space Name": element['space_name'],
  "Space Size": element['space_size'],
  "Used Space Size": element['space_used_size'],
  "Space Available": element['space_available_size'],
  "Physical Space Size":element['physical_space_size'] },
  );
}

// Printing in tabular form
console.table(myList)

Run index.js file using the following command:

node index.js

Output:

Reference: https://nodejs.org/api/v8.html#v8_v8_getheapspacestatistics