[v1.0.1] `options.parallel` on windows doesn't speed up compression (windows)

[matuscongrady]

Hello,

Parallel option doesn't seem to work on windows.

uglifyjs-webpack-plugin version: 1.0.1
webpack: 3.8.1
Windows: 10 (Version 1703, build 15063.674)

Tried using parallel option (both as a top-level argument to UglifyJSPlugin({ parallel: true }) and as a uglifyOptions: { parallel: true }
Tried both using true and specific number of threads.

Tried doing 50+ tests, and I didn't see any performance improvement.

[alexander-akait]

@mcongy please provide information about you node and computer information (count core CPU, memory and etc)

[matuscongrady]

Node: 8.7.0 (default installation using https://chocolatey.org/ )
CPU: Core i9 7900X (10 cores, 20 threads), 3.3Ghz
RAM: 32GB
64bit Win 10 Pro

Edit: I can run some test on other PC (that uses Win 10 aswell) when I return home. Will post results.

[alexander-akait]

@mcongy good, I will wait

[michael-ciniawsky]

@mcongy Please include your webpack.config.js aswell. Maybe related to #118

How many entries does your application have?
Could you check all running processes via the Task Manager while running webpack (#118)
Do you use caching { cache: true } or just parallel` ?

Caching brought the most benefits in my case, parallel aswell but not that much tbh

[matuscongrady]

Hello, I tried it on other Windows PC.

Node: 8.8.0
Windows 10 Education N
Core i3 7100 (2 cores, 4 threads, 3.7 GHz)
16 GB RAM

Uglify config:

new UglifyJSPlugin({
  parallel: false,
  uglifyOptions: {
    parallel: true,
    sourceMap: process.env.APP_ENV === 'production',
    output: {
      comments: false
    }
  }
})

App have only 1 entrypoint

Results:
No performance improvement. (All test did vary from 15.4 to 15.6 seconds no matter the parallel option).

[michael-ciniawsky]

How many assets (bundles) do you get ? 2 Cores === 1 Possibility to process of the main 'thread'.
When you run webpack could you inspect how many node.exe processes are spawned? (Task Manager)

[michael-ciniawsky]

Besides that fact and after some experimentation, please use { cache: true } 😛

[joshwiens]

The vast majority of the performance improvements are going to come from caching not parallel execution though you will see performance improvements in cache generation with parallel enabled.

[matuscongrady]

Ok, thanks for the explanation. Consider adding it to the docs, so it won't confuse other people.

I have one more question. Does cache options has some downfalls (e.g. having to manually invalidate the cache in certain cases)?

Thanks!