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Docs on improving compilation speed #10878
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It would be nice to know what types of things can cause a project to compile slowly. For example, if certain language features (large unions?? or generics?? or something else) will result in compilation slow-down, then developers can make decide if trade off is worth it.
Also, if some 3rd party libs are known to cause major slow downs, that would be good to know also.
At present, my #1 problem with TypeScript is the slow compile times. And the fact that the IDE is so slow to respond.
I just made a simple script that creates a typescript project, so I can parametrize certain characteristics. Then run tsc.
The only factor I found so far is file count and line count. Generics didn't do anything. Unions don't do anything.
Any idea that what else can I test?
- Interesting. The file count thing. I tend to prefer lots of small files. Might that be killing my perf?…On Sat, Jul 27, 2019 at 2:45 PM WEREMSOFT ***@***.***> wrote: I just made a simple script that creates a typescript project, so I can parametrize certain characteristics. Then run tsc. The only factor I found so far is file count and line count. Generics didn't do anything. Unions don't do anything. Any idea that what else can I test? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#10878?email_source=notifications&email_token=AAA6DVIKHE3IY5JQLECIGHTQBS6W3A5CNFSM4CPMJMU2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD26TEEI#issuecomment-515715601>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAA6DVM2ONWPOIZW3657IILQBS6W3ANCNFSM4CPMJMUQ> .-- Dave Ford Developer and Trainer Smart Soft https://smart-soft.com <http://www.smart-soft.com> https://twitter.com/@daveford https://medium.com/@daveford
WEREMSOFT I recommend adding in tests for
this["foo"], in particular like this:class Foo { private _foo: number = 1; } class Bar extends Foo { private _bar: number = 2; } class Qux { public _qux!: Foo; public get qux(): this["_qux"] { return this._qux; } } class Corge extends Qux { public _qux!: Bar; } const x1: Foo = new Qux().qux; const x2: Bar = new Corge().qux;
We use this pattern a lot. The things to parameterize are how deeply nested the class hierarchy is, how many methods use the
this["foo"]type, and how big the classes are (e.g. number of methods/properties).One interesting example is this change to the styled-components types, which increased compile time by 20x. Background discussion here: #30663.
It would be interesting to explore why; I'd love some principles to avoid issues like that in my own code, and tools to find problematic types in general in large codebases. Issues aren't always going to be caused by an obvious dependency upgrade like this.
#31612 might also be interesting, as another catastrophic performance case that docs/tooling should warn you about, and show you how to avoid.
With the
--watchflag on, a recompile of an existing file generally takes 4 seconds now in our project. This isn't terrible at all, but the wait time has grown since we started using it.I was wondering what factors affect incremental compilation speed? With TypeScript gaining widespread adoption, I think it'll be very important to developer experience to have a doc page detailing the main contributors to incremental compilation time and ways to improve it.
P.S. Note I meant incremental compilation speed with
--watch, not a full recompile.