The features of the new version of node.js lead to an increase in the memory usage of the process

[longG4]

Details

Our business process has an upper limit baseline requirement，currently switching to a new version of node.js results in an increase in memory.node version v18.14.1 vs v14.21.3, the memory of the same sample code increased by about 10mb. Why did this happen, and what factors？

Node.js version

18.14.1

Example code

The sample code indexTest.js as follows:

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
  res.send('Hello World!')
})

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`);
  console.info(`process info: rss ${(pro.rss / 1048576).toFixed(2)}MB heapTotal ${(pro.heapTotal / 1048576).toFixed(2)}MB heapUsed ${(pro.heapUsed / 1048576).toFixed(2)}MB external ${(pro.external / 1048576).toFixed(2)}MB`);
})

With express 4.18.1 we use the command: ./node indexTest.js we can see memory performance information is as follows: node v14.21.3

root@DESKTOP-TKJT03L:/opt/nodejsTest/node-14# ./node indexTest.js
Example app listening on port 3000
process info: rss 42.95MB heapTotal 10.33MB heapUsed 6.70MB external 1.47MB
process info: rss 42.95MB heapTotal 10.33MB heapUsed 6.71MB external 1.47MB
process info: rss 42.95MB heapTotal 10.33MB heapUsed 6.71MB external 1.47MB
process info: rss 42.95MB heapTotal 10.33MB heapUsed 6.71MB external 1.47MB
process info: rss 39.43MB heapTotal 6.70MB heapUsed 4.83MB external 1.39MB
process info: rss 39.43MB heapTotal 6.70MB heapUsed 4.85MB external 1.39MB
process info: rss 39.43MB heapTotal 6.70MB heapUsed 4.85MB external 1.39MB
process info: rss 39.43MB heapTotal 6.70MB heapUsed 4.86MB external 1.39MB

node v18.14.1

root@DESKTOP-TKJT03L:/opt/nodejsTest/node-14# ./node indexTest.js
Example app listening on port 3000
root@DESKTOP-TKJT03L:/opt/nodejsTest/node-18# ./node indexTest.js
Example app listening on port 3000
process info: rss 54.73MB heapTotal 11.84MB heapUsed 8.70MB external 0.75MB
process info: rss 54.73MB heapTotal 11.84MB heapUsed 8.71MB external 0.75MB
process info: rss 54.73MB heapTotal 11.84MB heapUsed 8.71MB external 0.75MB
process info: rss 54.73MB heapTotal 11.84MB heapUsed 8.71MB external 0.75MB
process info: rss 51.95MB heapTotal 9.09MB heapUsed 7.17MB external 0.72MB
process info: rss 51.95MB heapTotal 9.09MB heapUsed 7.37MB external 0.72MB
process info: rss 51.95MB heapTotal 9.09MB heapUsed 7.43MB external 0.72MB
process info: rss 51.95MB heapTotal 9.09MB heapUsed 7.44MB external 0.72MB
process info: rss 51.95MB heapTotal 9.09MB heapUsed 7.44MB external 0.72MB

Operating system

Ubuntu 18.04.5 kernel version is 5.10.16.3

Scope

other

Module and version

Not applicable.

[preveen-stack]

cc @nodejs/performance PTAL

[mcollina]

@longG4 if your business has such a tight dependency on Node.js, I recommend you to join the team that maintains it. In this way you can analyze and fix those situations when they arises. We are always looking for more companies that are willing to contribute back.

So many things has changed from Node.js v14 and v18, and some of those could be controlled via ./configure options. I'd recommend you to explore them.

[longG4]

@mcollina the ./configure options. you mean the configure.py in the source directory?

[tniessen]

You can also try bisecting (e.g., just by testing various Node.js versions) to find out if any particular release caused the increase in memory usage. There are thousands of changes between Node.js 14 and Node.js 18, so we cannot possibly say which of them contribute to this.

[Aghassi]

For us, we went from Node 16 to Node 18 and saw a 30% increase in memory usage across all apps. We haven't done a git bisect yet given that that would require us to build every commit of Node to find the exact commit that introduced the regression. It's a shame that upgrading to be on LTS causes us to have to use more memory.

What information or profiling would be helpful to maintainers to help narrow this down? We'd love to work with the community to find the root cause if possible.

[RafaelGSS]

For us, we went from Node 16 to Node 18 and saw a 30% increase in memory usage across all apps. We haven't done a git bisect yet given that that would require us to build every commit of Node to find the exact commit that introduced the regression. It's a shame that upgrading to be on LTS causes us to have to use more memory.

What information or profiling would be helpful to maintainers to help narrow this down? We'd love to work with the community to find the root cause if possible.

Was it noticed from the major update or some semver-minors? You can check it by comparing v18.0.0 against v16.15.0

[Aghassi]

For us we went from 16.18 to 18.12 and that's when we noticed it. We did not attempt any versions in between. From 18.12 to 18.18.2 we did not see the memory usage change. So the increase was between majors. Granted, we didn't test any of version 17 when we made the jump. I know that's less than helpful, but given we are in a larger organization coordinating a node upgrade is a bit costly so it's hard to jump between versions at the moment. I can maybe see if I have spare cycles to show a meaningful reproduction publicly, but I make no guarantees.

To answer your question, it was noticed in the major jump

[Boardtale]

I did not put much attention into it, but I can concur here. Migrated from Node 16 to Node 18 and started to see my Google Cloud Functions getting OOM errors, so I've started digging and found this thread.

[Lewiscowles1986]

So just to collate what was written here:

16.18 -> 20 seems to result in RSS increase 14.21.3 -> 20 seems to result in RSS increase

I'm not sure which patch version, so I've just gone with whatever nvm install 16.18 does.

The original code didn't quite work from copy -> paste and doesn't lend itself to analysis IMO

Re-jigged copy-paste-able index.js

const process = require('process');
const express = require('express');
const app = express();
const port = 3000;

app.get('/', (req, res) => {
  res.send('Hello World!');
})

app.listen(port, () => {
  const processMemory = process.memoryUsage();
  console.info(JSON.stringify(processMemory));
});

NOTE: I am not, and have no intention of logging twice or trying to format as MB

Then I wrote a little script to test an arbitrary node version and run the index.js script...

kill -15 $(pgrep node); rm -f $(node --version).log && for run in {1..100}; do; node index.js >> $(node --version).log & sleep 1 && kill -15 $(pgrep node) >/dev/null; done;

NOTE This script is greedy and lazy, and should be run on an isolated machine, not one with other nodeJS instances that might be killed. I did switch from sigkill to sigterm to try to be a bit more polite.

I then after an initial npm init and npm install express in the lowest version of node, just used nvm use {version} and then ran the above script.

I'm honestly not bothered by increased RAM for newer features of Node. While I suspect some of this can be compiled away; I'd likely not use Node for something where 128MB ram or less wasn't available. None of the examples even take up 64MB RAM, and there is a lot of overhead to do cool work in that memory set. I think the trade-off for NodeJS is good, but also wonder if profile guided optimization, or something of that direction (including custom compiled nodejs) might be more your bag at that small size of RAM

Here are the outputs for lts versions:

lts/fermium -> v14.21.3
lts/gallium -> v16.20.2
lts/hydrogen -> v18.20.4
lts/iron -> v20.17.0

nodejs-express-minimal-rss-logs.zip

[Lewiscowles1986]

Also I just wrote another script because as I looked at the results, I thought. This isn't NodeJS alone.

Here's a 3-liner

const process = require('process');
const processMemory = process.memoryUsage();
console.info(JSON.stringify(processMemory));

Same node versions

NOTE: 16.18 is also in there, as it was in the last set of logs because it's listed in this thread.

Less than 32MB is the summary across all nodeJS version. 🎩 to the team, who really are doing an amazing job at maintaining and creating such a powerful expressive tool, which I often tell people is the most successful C++ API

really-minimal-nodejs-logs.zip

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[joyeecheung]

Given that this can be reproduced with various completely different snippets this looks more like a V8 issue than a Node.js issue. Each major version of Node.js typically gets a substantial amount of V8 changes and the V8 GC strategy is constantly moving.

[Lewiscowles1986]

@joyeecheung it's not been proven an issue with any minimally reproducible example https://github.com/nodejs/help/issues/4228#issuecomment-2303829392 has a base v8 script.

It's more likely that the memory and performance trade-offs between versions exist, as is the case with C++, Java and every other language or framework. Please only post if you have a minimal example of NodeJS using more RAM, with quantification of exact version and memory usage, platform etc.