map.remove() doesn’t clean up data inside Worker class -> memory leak

[pasieronen]

maplibre-gl-js version: 4.0.2

browser: Chrome 122.0.6261.57

DEMO: https://jsbin.com/moburomadu/edit?html,output

The Worker class has several caches (layerIndexes, availableImages, workerSources, demWorkerSources) that use mapId as a key. It looks like they won’t get cleaned up by map.remove() (or anything else except terminating the worker), and thus leak memory if you remove and create new maps often (e.g. inside a single-page app).

You can observe this in Chrome DevTools "Memory" tab (memory usage for the worker keeps growing), or directly by looking at the data (select the worker in "Console" tab and print Object.keys(worker.layerIndexes)).

I guess the way to fix this would be to send a removeMap message to the Worker? I can do a PR for that next...