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PHP in a worker

createPhp() runs PHP in the main thread of the page: the page freezes while PHP runs, for 80 ms when Symfony answers a request, for example. The build for the web runs it in a Web Worker too, with createPhpInWorker():

import { createPhpInWorker } from './php-web.mjs';

const php = await createPhpInWorker({ persist: '/my-page' });
const { stdout } = await php.runFile('/app/page.php');

await php.FS.writeFile('/tmp/input.json', data);

It starts php-web.mjs in a worker, that runs createPhp(). runFile(), runCode() and request() are the same, persist too: a worker has IndexedDB and the Web Locks. The differences:

  • the methods of php.FS return a promise, of what the method returns, and what they are given, or return, is copied. The node of FS.mkdir() or FS.symlink() can not be, the promise gives nothing. An FS.lookupPath() or an FS.analyzePath() can not be either, the promise is rejected;
  • the options are copied to the worker: no function, as locateFile. The .wasm file is the one next to php-web.mjs, that must be on the origin of the page, as any worker;
  • the stack of the JavaScript engine is smaller in a worker of Chrome: a recursion goes about 1,000 callbacks deep, instead of 2,000 (see Limitations);
  • php.terminate() stops the worker, and frees its memory: once PHP aborted, before creating another one.