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When using TypeScript 4.x, live-reload is much slower

See original GitHub issue

Some context could be found in Discord. TLDR is tsc --noEmit --watch finishes immediately, but ember serve takes a few seconds when a TS file changes. Running it with DEBUG=ember-cli-typescript* shows:

file changed helpers/create-immediate-value.ts
⠙ building...   ember-cli-typescript:typecheck-worker Typecheck starting +339ms
⠏ building...   ember-cli-typescript:typecheck-worker Typecheck complete (0 diagnostics) +5s

cc @dfreeman

Issue Analytics

State:
Created 3 years ago
Reactions:1
Comments:7 (5 by maintainers)

Top GitHub Comments

2reactions

boris-petrovcommented, Oct 27, 2020

TypeScript 4.0.5 is out and this issue is fixed. Thanks to @dfreeman for resolving it with the TS guys!

2reactions

dfreemancommented, Sep 28, 2020

I spent a little time with this this afternoon, and the performance characteristics of the compiler API we use to capture typechecking results seem to have changed in 4.0. Specifically, the version of that API that only tracks diagnostics has become much slower than the version that also tracks emitting files, which is a bit surprising to me.

I opened https://github.com/microsoft/TypeScript/issues/40808, and we’ll see if this is a bug and figure out where to go from there.