Guidance on reducing heap usage of large typings?

I maintain google/schema-dts which generates typings for schema.org JSON-LD. The generated typings are ~10k loc and involves a lot of type unions (e.g. Thing can be Organization or CreativeWork or Person or …), and these can get pretty nested.

Compiling these works for me and the vast majority of users. But I get constant reports of JavaScript heap OOM errors from users consuming the typings. See google/schema-dts#34. I haven’t been able to repro this at all, but I’m still hoping for some guidance on getting a better memory footprint for the type checker.

FYI, the .d.ts file looks something like this: https://unpkg.com/schema-dts@0.5.1/schema.d.ts

Questions (I’d take answers to any of these):

1. Are there better strategies for writing these in a more memory friendly way? e.g. naming intermediate types, or declaring all properties in one huge object and defining respective types in terms of Pick<>?
2. Are there any profiling tools that anyone would recommend using to track this down?
3. any other advice is appreciated.

Unfortunately splitting the types up isn’t an option (at least not obviously) because the types are deeply self referential.

[amcasey]

I ran #37785 on your example and it revealed precisely nothing. So either this is a different class of slowdown than we were expecting or the tool is useless on .d.ts files. I’ll have to investigate more to figure out which.

[Eyas]

@amcasey if it helps/narrows anything down, some users are reporting that TypeDoc is also OOMing with the linked library. Not sure if TypeDoc uses any of the typescript lib when running through types.