Where do I set 'NODE_OPTIONS="--max-old-space-size=2048"'

Question

When I run "npm start" in application I get the following error - FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory

Most of the solutions posted online are about increasing memory with NODE_OPTIONS="--max-old-space-size=2048". But I have no idea where to set this. Some posts talked about a .bashrc file which my project does not have. I'm also on a windows system. The "npm start" command runs "npm run build-semantic && react-scripts start" as set up in package.json.

Solution 1

There could be multiple ways to use this flag. I'm using 8GB as an example to allocate the amount of memory but you could select as per your project.

First option

What OP was originally looking for was a way to set an Environment Variable. The NODE_OPTIONS --max-old-space-size environment variable allows to increase Node's max heap size. Setting an environmental variable allows Node to read this value from your environment and so we don't need to pass this value as an argument every time we run Node command. This is set as a global value and can be utilized by every Node process.

The process of setting an environment variable depends on the OS. Here are two SO posts on this:

• Linux: Setting environment variables in Linux using Bash
• Windows: How to set Environment variables from Windows

In summary, set NODE_OPTIONS.

export NODE_OPTIONS="--max-old-space-size=8192"

If you put this command in the terminal session, you will need to do it in every new session. To avoid that, you can put that in the shell script file and the terminal will load it automatically for you.

The .bashrc file OP mentioned exists on Linux environment and most comments refer to reload the bash as a quick way like source ~/.bashrc which loads the env vars in the current session. One can always restart the terminal to reload but the former is mostly preferred! Again, ignore this if using Windows.

Second option

Now, if setting environment variable is not a preferred option, one can always use --max-old-space-size either while running the node command. Example from Nodejs.org documentation

$ node --max-old-space-size=8192 index.js

Third option

Alternatively, as the OP has already answered, we can set this per project basis but the implementation might vary depending on the project.

For npmscripts this Git comments answers it Best way to set --max-old-space-size when running npm (I reckon it's hyphens not underscore):

"scripts": 
{
    "start": "cross-env NODE_OPTIONS=--max-old-space-size=8192 webpack"
}

In Angular projects, you could define it like:

"scripts":
{
    "build-prod": "node --max-old-space-size=8192 ./node_modules/@angular/cli/bin/ng build --configuration=production"
}

Solution 2

If you are on Unix then type

export NODE_OPTIONS=--max-old-space-size=<size in bits>

in the terminal.

If you are on windows then run

set NODE_OPTIONS=--max-old-space-size=<size in bits>

Solution 3

In your terminal type this:

export NODE_OPTIONS="--max-old-space-size=8192"

Solution 4

@Zephyr You can set the max value in your package.json

scripts": {
"start": "node  --max-old-space-size=1024 ./bin/www"
}

Also, you can even set the max size while starting you node application on through command line

node --max-old-space-size=1024 <path of your main file(For example server.js)>

Hope it helps :)

Solution 5

The tricky thing here, is that you couldn't know how much memory will have on the production server, and limit the memory with a fixed value could be not the best option.

I wrote a code, to get the total memory on a linux machine, deduct 400mb (to other server resources), and assign it as node memory limit.

  FREE=$(free -m);
  echo "FREE: ${FREE}"
  FREE_FINAL=$(echo "$FREE" | grep -F Mem:  | grep -o "[0-9]*" | grep -o -m1 "^[0-9]*")
  echo "FREE_FINAL: ${FREE_FINAL}"
  MEM_LIMIT=$(($FREE_FINAL-400))
  echo "MEM_LIMIT: ${MEM_LIMIT}"
  echo " - "

  export MEMORY_LIMIT="${MEM_LIMIT:=3500}";

  export NODE_OPTIONS="--max-old-space-size=${MEMORY_LIMIT}"
  echo "NODE_OPTIONS: ${NODE_OPTIONS}"

You can create a build.sh or start.sh file, that will be called on package.json, to set the right limit.

If you use docker, it can be added to a entrypoint.sh file (that will run on build time, but on each docker start as well).

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Comments

[Zephyr]

My start script needs to have "npm run build-semantic && react-scripts start" so do I just add "--max-old-space-size=1024 ./bin/www" to it?

[Zephyr]

index.js inside client/src/

[Gurpinder]

In your package.json under scripts use the following code scripts": { "start": "node --max-old-space-size=1024 <start point of your node application>" }

[Gurpinder]

let me know if you are still facing an issue

[kernal_lora]

Is there anyway to get the old space param dynamically in package.json? I mean template like placeholder if we place in package.json automatic evaluation, is that possible and how ?

[d2207]

didnt work, I got error: unknown option '--max-old-space-size=6144'

[anevaude]

@d2207 - If you're on Windows, change the word "export" to "set".

[Molomby]

max-old-space-size is specified in megabytes, not bits, fyi

[Steven J]

the first option i would NOT recommand if this is on your main windows installation. I had side effects with other apps not opening like postman or whatsapp for instance. Better to set it at project level and not windows env level github.com/postmanlabs/postman-app-support/issues/6035

[sandiejat]

There are some cases where env vars could be a preferred (better) choice. Examples of such cases are - creating private base layer for containers or dedicated production build nodes. Keeping settings to the project level has its advantages obviously.

[Dilip Kumar Yadav]

With second option I am getting error: <--- Last few GCs ---> <--- JS stacktrace ---> # # Fatal process OOM in insufficient memory to create an Isolate #

[sandiejat]

@DilipKumarYadav Two things to note - did you use hyphens? For quite some time I used underscores mistakenly and never worked. Also, if the project is bigger, as in my case, I had to assign 10240 (10GB) for my build to succeed. There was no way around it. We had to upgrade to Angular13 and let go of some large libraries where tree shaking wasn't possible.