'threads' doesn't compatiable with webpack multi-compiler

[fangbinwei]

• Operating System: macOS
• Node Version: 12.14.0
• NPM Version: 6.13.4 (yarn 1.22.10)
• webpack Version: 4.44.2/webpack@5
• eslint-webpack-plugin Version: 2.4.1

Thanks to the contributors of this plugin, it solves many pain points of eslint-loader.

We are using webpack to output different type of bundle through multi-compiler. If setting threads of eslint-webpack-plugin, the output will be incomplete. So it's not recommended to use this option with webpack multi-compiler?
Or it can be fixed in webpack? The result of webpack@4 and webpack@5 is similar.

Expected Behavior

bundle output should be

dist
├── desktop.js
└── mobile.js

Actual Behavior

bundle output is incomplete

dist
├── desktop.js

[email protected] and [email protected] with threads

bundle output: incomplete
console output

[webpack-cli] Compilation finished
✨  Done in 2.93s.

Some of our project's tests are based on the output of webpack. So the incomplete console output let the tests fail after bumping the version of eslint-webpack-plugin to 2.4.1.

[email protected] and [email protected] with threads

bundle output: High probability incomplete, Small probability complete(according to the test of reproducible repo)
console output

[webpack-cli] Compilation finished
[webpack-cli] Compilation finished
Hash: d3616dbfeab31a03f79ed3616dbfeab31a03f79e
Version: webpack 4.44.2
Child mobile:
    Hash: d3616dbfeab31a03f79e
    Time: 508ms
    Built at: 12/02/2020 5:04:22 AM
        Asset        Size  Chunks             Chunk Names
    mobile.js  1010 bytes       0  [emitted]  main
    Entrypoint main = mobile.js
    [0] ./src/index.js 38 bytes {0} [built]
Child desktop:
    Hash: d3616dbfeab31a03f79e
    Time: 537ms
    Built at: 12/02/2020 5:04:22 AM
         Asset        Size  Chunks             Chunk Names
    desktop.js  1010 bytes       0  [emitted]  main
    Entrypoint main = desktop.js
    [0] ./src/index.js 38 bytes {0} [built]
✨  Done in 2.12s.

How Do We Reproduce?

Reproducible repo