node worker_threads in electron app fails, causing pthread usage to fail

[koush]

Emscripten attempts to use node's worker_threads module in an electron app BrowserWindow (nodeIntegration: true), which will successfully require('worker_threads') but attempting to contstruct a Worker will fail with "worker threads are not supported in this node environment".

Emscripten should either detect the electron environment and use Web workers, or prefer Web Workers in all cases.

[sbc100]

We currently don't have any direct support (or testing in) Electron. If we fix this it might be nice to add some testing for this new environment.

[koush]

I am currently patching the following files as part of my build process:
tfjs-backend-wasm-threaded-simd.js
tfjs-backend-wasm-threaded-simd.worker.js

The fix is straightforward in the hack patch I am doing:

var ENVIRONMENT_IS_NODE=typeof process=="object"&&typeof process.versions=="object"&&typeof process.versions.node=="string";

becomes:

var ENVIRONMENT_IS_NODE=typeof process=="object"&&typeof process.versions=="object"&&typeof process.versions.node=="string"&& (process.versions.electron=="undefined" || process.type === 'browser');

I think the original source is here:

emscripten/src/shell.js

Line 118 in c9d568a

var ENVIRONMENT_IS_NODE = typeof process == 'object' && typeof process.versions == 'object' && typeof process.versions.node == 'string';

---

Electron process.type docs: https://www.electronjs.org/docs/latest/api/process#processtype-readonly

// explainer on the electron process checks

// process is plain node
process.versions.electron=="undefined"
// process is electron, but is the main process, which can use worker_threads.
process.type === 'browser'