Some UV_THREADPOOL_SIZE count does not affect zlib.gzip method performance

[jeongsik-woo]

Details

When I run zlib.gzip, I expect the gzip to be handled by threads in a UV_THREADPOOL with the number of threads set by UV_THREADPOOL_SIZE.

So, I thought that increasing the UV_THREADPOOL_SIZE would naturally result in more threads running concurrently, which would improve performance, but this was not the case.

I experimented with UV_THREADPOOL_SIZE values of 4, 8, 16 and 32. The modification from 4 to 8 resulted in a nearly 2x performance increase, while the modification from 8 to 16 resulted in almost no performance difference. I thought that setting UV_THREADPOOL_SIZE to 16 would make the job faster by having 16 UV_THREADs running at the same time to do 32 gzips, but it didn't.

Do you have any idea why?

test results is below.

UV_THREADPOOL_SIZE 32
3531

UV_THREADPOOL_SIZE 16
3615

UV_THREADPOOL_SIZE 8
3634

UV_THREADPOOL_SIZE 4
5185

Node.js version

v18.17.0

Example code

const zlib = require('zlib');
const jsonData = require('./large-file.json'); // large size file. 28MB byte.

console.log('UV_THREADPOOL_SIZE', process.env.UV_THREADPOOL_SIZE);

const stringData = JSON.stringify(jsonData);

const length = 32;
const result = [];
const begin = new Date();
let end = null;
for (let i = 1; i <= length; i++) {
  zlib.gzip(stringData, {level: 9}, () => {
    result.push(1);
    if (result.length === length) {
      end = new Date();
    }
  });
}

setTimeout(() => {
    console.log(end.getTime() - begin.getTime());

}, 1000 * 120);

Operating system

Darwin 21.6.0 Darwin Kernel Version 21.6.0: Sat Jun 18 17:07:22 PDT 2022; root:xnu-8020.140.41~1/RELEASE_ARM64_T6000 arm64

Scope

runtime

Module and version

Not applicable.

[jeongsik-woo]

large size file exmple: https://github.com/json-iterator/test-data/blob/master/large-file.json

[preveen-stack]

cc @nodejs/libuv

[github-actions[bot]]

It seems there has been no activity on this issue for a while, and it is being closed in 30 days. If you believe this issue should remain open, please leave a comment. If you need further assistance or have questions, you can also search for similar issues on Stack Overflow. Make sure to look at the README file for the most updated links.

[github-actions[bot]]

It seems there has been no activity on this issue for a while, and it is being closed. If you believe this issue should remain open, please leave a comment. If you need further assistance or have questions, you can also search for similar issues on Stack Overflow. Make sure to look at the README file for the most updated links.