microsoft
Cache FS in LS
I think this is right; within a Project, cache the FS accesses and clear them out on graph update for safety. Then, things get faster in load time in module resolution and so on.
Not a mega fan of the whole host wrapping but I don't see a better way.
We did this in Strada too (though we did it before creating program in service) this is known to help perf.
Unfortunately this method doesn't really work, the project test system replaces the FS out from under the cache, but the cache FS grabs the FS on creation.
I've been able to change the tests to not do that, but I'm not clearing the cache in places that seemingly we need it. So this will need more work.
CI fails because the new ATA code runs before updateGraph and therefore reads from the cached FS before it's cleared.