Nishil Patel
May 1, 2024
7 min read
In this article, you’ll learn how to fix the “JavaScript heap out of memory” error. You’ll also learn what happens behind the scenes when you encounter this error, what causes it, and what you can do to identify and prevent memory-related errors in your JS applications.
1.
Introduction
2.
Understanding JavaScript V8 Engine
3.
What is the “JavaScript heap out of memory” Error?
4.
What Causes the “JavaScript heap out of memory” Error?
5.
How to Identify the Error?
6.
How to Fix the “JavaScript heap out of memory” Error?
7.
How to Prevent Memory Issues?
8.
FAQs
You may come across the ‘JavaScript heap out of memory’ error when running medium to large-scale JavaScript projects in your Node.js environment. The JavaScript V8 engine commonly throws this error, but you can resolve it swiftly with a few straightforward adjustments. In this article, we will explore the causes of the error and demonstrate how to fix it.
Developed by Google, the JavaScript V8 engine is a program that executes your JS code. It powers Chrome and also the Node.js runtime. The V8 engine comprises:
All three of them work together to execute your application code on the server.
JavaScript uses the heap space for garbage collection to manage memory and smoothly run your application code. The heap memory is dynamically allocated by the V8 engine based on a certain memory limit.
When the default memory allocation for the heap space in JavaScript is not enough to run your application, your program crashes throwing the “FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory” error.
This error may sometimes look different in your JS stacktrace, but they are largely caused by similar reasons. Here are some variations of the heap out of memory error in JavaScript:
Insufficient memory space allocation can occur due to several reasons. Here are some notable ones:
Complex applications typically handle large data processing tasks, datasets, and data structures by running billions of calculations behind the scenes. This could quickly gobble default allocated memory for the program causing the error.
If your program has any unknown infinite/non-terminating loops or contains inefficient or loosely written recursive functions, it triggers the heap out of memory error. Both these operations are memory guzzlers.
Poorly written or inefficient algorithms can sometimes exceed the expected space complexity — that’s the amount of memory an algorithm needs relative to the size of its input. This can lead to memory allocation issues in your application, potentially causing an error if the program attempts to use more memory than is available in the heap.
Memory leaks in your JS application can cause erroneous code runs. Memory leaks happen when the V8 engine’s garbage collector cannot release allocated (that’s actually unused) memory for your app to use. In such cases, the JS heap runs out of memory — leading to the error.
Here are some common scenarios where memory leaks happen in your JS application:
Also Read: How to Fix “Objects are not Valid as a React Child” Error
There are several methods and tools to identify memory-related errors in your JS code. You can use:
Let’s briefly cover some top ways to identify the error with these two:
Chrome provides a host of tools to analyze and monitor memory-related issues. Here are some:
You can also use Chrome Task Manager (hit Shift + Esc to open) to monitor a page’s memory use in real time, aiding in the initial analysis of memory problems.
Also Read: How to Clear DNS Cache on Chrome [Updated] with Chrome://Net-Internals/#DNS
There are a bunch of Node.js techniques that you can use to identify memory errors in your code.
Here’s what the code and output looks like:
You get the memory info in KBs by default. You can convert the values to MB for better readability like below:
Fixing the out of memory error is super simple. Here’s how:
Increasing the allocated heap memory for the Node.js V8 engine is the quick and dirty solution to resolve the issue. However, proper memory profiling and analysis are recommended before applying this fix to ensure it’s the only way around.
Here’s how it works:
For Windows
It allocates 4GB of memory to the memory heap and should fix the error.
You can also allocate more memory to the node global variable in Windows OS. This will allocate memory for all your Node.js apps. Here’s how:
The error should be gone now when you run your Node.js app.
For Linux and MacOS
Open the MacOS/Linux terminal and run this command to allocate 4GB for the heap memory for your node app:
node --max-old-space-size=4096 main.js
While increasing the heap size can provide a quick fix, it’s crucial to identify and resolve the root cause of the memory issue for a long-term solution.
Here are some ways to keep the heap out of memory error at bay:
Keep track of the unwanted global variables, closures, and inefficient code logic in your applications. Using streams and buffers while handling large amounts of data can also help keep your code optimized and prevent out of memory errors.
Ensure that your code is thoroughly tested with relevant testing methods and in a production-like environment. Real-world conditions push your application to its limits and memory leaks are often identified in these test runs.
Writing efficient code with the best coding practices can help prevent memory leaks in your application. Refer to the official language documentation if you find yourself stuck with memory-related issues.
Newer Node.js versions are pretty solid in memory management. There’s a good chance that such underlying or unknown issues have already been identified and fixed in recent Node.js packages. However, if you have constraints to using older versions for your project needs, you can always use suitable fixes like those mentioned above.
Nishil is a successful serial entrepreneur. He has more than a decade of experience in the software industry. He advocates for a culture of excellence in every software product.
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