How to Solve "Process out of Memory Exception" in Node.js ?

A "Process out of Memory Exception" in Node.js typically occurs when your application consumes more memory than is available, causing the Node.js process to crash. This issue is critical in applications that handle large datasets, process intensive tasks, or have memory leaks. Here’s a comprehensive guide to solving this problem:

Understanding the Problem

Causes

• Large Data Handling: Processing large files or datasets in memory.
• Memory Leaks: Unintentionally retaining objects in memory longer than necessary.
• Inefficient Code: Suboptimal algorithms or operations that use excessive memory.
• Excessive Concurrent Operations: Running too many processes or threads concurrently.

Indication

• Frequent crashes with error messages like FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory.

Step to Run Application: Run the application using the following command from the root directory of the project

node app.js

Output: We will get a FATAL ERROR saying FatalProcessOutOfMemory as shown below.

Note: The default memory allocated to a node.js program is 512MB on 32-bit systems and 1024MB on 64-bit systems (Above program was run on a 64-bit system).

Installation Steps

Step 1: Make a folder structure for the project.

mkdir myapp

Step 2: Navigate to the project directory

cd myapp

Step 3: Initialize the NodeJs project inside the myapp folder.

npm init -y

Project Structure

Solution

To solve the "Process out of Memory Exception" in Node.js, increase memory limit with --max-old-space-size, optimize memory usage, monitor memory consumption, and refactor code to handle large data efficiently.

Syntax

node --max-old-space-size=<SPACE_REQD> app.js

Parameters:

• SPACE_REQD: Pass the increased memory space (in Megabytes).

Example 1:

In the following example, we increase the memory space requirements to 2048MB (2GB). Use the command below to run the JS file (app.js in this case)

Syntax:

node --max-old-space-size=2048 app.js

With this command, our program runs perfectly without any exceptions. If you use the standard node index.js command, it will throw a FatalProcessOutOfMemory exception because the program exceeds the default allocated memory space. By using the --max-old-space-size option, we increase the allocated memory space, preventing the program from running out of memory.

Step to Run Application: Run the application using the following command from the root directory of the project

node app.js

Example 2:

In the following example, we increase the memory space requirements to 3072MB (3GB). Use the command below to run the JS file (app.js in this case):

Syntax: 

node --max-old-space-size=3072 app.js

If you use the standard node index.js command, it will throw a FatalProcessOutOfMemory exception because the program exceeds the default allocated memory space. By using the --max-old-space-size option, we increase the allocated memory space, preventing the program from running out of memory.

Step to Run Application: Run the application using the following command from the root directory of the project

node app.js