Loading multiple spritesheet JSONs with related_multi_packs linking to each other can cause PIXI.Assets.load() to deadlock and never resolve

Expected Behavior

When loading multiple spritesheets that link to each other with related_multi_packs, it should be able to load them all without deadlocking.

Current Behavior

If you try to load multiple spritesheets that use TexturePacker’s related_multi_packs in its JSON file and that link to each other, it will attempt to load them even if they are already being loaded by another spritesheet, causing a deadlock.

{"frames": {

...

"meta": {
	"app": "https://www.codeandweb.com/texturepacker",
	"version": "1.0",
	"image": "my-numbers-0.png",
	"format": "RGBA8888",
	"size": {"w":512,"h":512},
	"scale": "1",
	"related_multi_packs": [ "my-numbers-1.json", "my-numbers-2.json" ],
	"smartupdate": "$TexturePacker:SmartUpdate:ea7b985de3af11d8d7e7bff73b074569:80778496bccc42d13437c459447a7090:06d8674a9e41fa7741f7530a3f8cb3c3$"
}
}

    const spritesheets: string[] = [
        "assets/my-numbers-0.json",
        "assets/my-numbers-1.json",
        "assets/my-numbers-2.json",
    ]
    console.log("Trying to load spritesheets all in a single load()...");
    await Assets.load(spritesheets);
    console.log("Never reached!");

Possible Solution

Either the user has to carefully make sure to load multi-pack spritesheets one by one, in case it links to another spritesheet and loads it automatically, or the asset loader should implement a check to make sure it is not already loading that spritesheet so it doesn’t deadlock itself.

Steps to Reproduce

1. Download, extract and run the barebones demo project linked below (“npm i”, “npm run local:buildRun”)
2. Open the webpage and check the console to see that “Never reached!” is never printed.
3. Comment out test_one() and uncomment test_two() to see that the promises never resolve even when loading spritesheets individually all at once.

Environment

• pixi.js version: 7.0.3 & also affecting 6.5.8
• Browser & Version: Edge Version 107.0.1418.35, Chrome Version 107.0.5304.88 (Official Build) (64-bit), Firefox 106.0.4 (64-bit)
• OS & Version: Windows 11
• Running Example: related_multi_packs_bug_demo.zip

[SuperSodaSea]

I’m trying to solve this problem 😃

[bigtimebuddy]

Animations across multiple spritesheets is an open issue see #7000.

Concatenating multiple spritesheets into a single Spritesheet object would likely solve this, we could then merge animations with the same key.