What are the use cases for Yarn `enableGlobalCache`?

Question

The Yarn package manager has an option called enableGlobalCache which makes yarn store its package cache in a global folder. Yarn's normal mode is to store its cache in <cacheFolder> which is in the project folder by default (.yarn/cache).

What is the reason to use enableGlobalCache? Is it just for saving disk space? Are there any downsides?

I am asking because I'm puzzled — if it has a use case and there are no downsides, then why is it not the default?

Answer 1

Yarn V4 answer

Doc says:

Define whether the cache should be shared between all local projects.

If true (the default), Yarn will store the cache files into a folder located within globalFolder instead of respecting cacheFolder.

So you were right, there is no downside, but as it was a complete new feature (app local cache and global cache), the precautionary principle was to disable globalCache by default. Now it's enabled by default in Yarn v4.