Building performance is slowdown

[thekiba]

TypeScript Version: 3.2.0-dev.201xxxxx

Search Terms:
performance, slowdown, degradation

Code:
After upgrading to typescript 3.1.3, our application has been building for a very long time. The total time has increased tenfold. By profiling the build, I found the reason for the slowdown in performance.

The screenshot shows a call to this method:
https://github.com/Microsoft/TypeScript/pull/26192/files#diff-08a3cc4f1f9a51dbb468c2810f5229d3R968

oldProgramState.program.getSourceFiles().find(...)

When I rolled back the commit changes, the performance problem was solved. But I don’t know how to fix that and so that the PR assertion pass:
https://github.com/Microsoft/TypeScript/pull/26192/files#diff-6f2ace9c4058a2bb2afe0560f9990e33R402

Expected behavior:
Performance improvement

Actual behavior:
Performance is slowdown

Related Issues:
#26192

[ajafff]

Looking at that code again, I don't know how it could cause a noticeable slowdown. That would probably require thousands or millions of files in your program.

How are you running tsc to hit that path of the code? tsc -w or some custom build tool?
How many files are in your program? You can find out using --diagnostics flag of tsc.

[thekiba]

The count of files in the project ~10k.

I am using @angular/cli. And I tried to set the compilerOptions.diagnostics flag in tsconfig.json, but I don't receive any information.

[ajafff]

After investigating further, it turns out this code may be executed for each import (or type reference directive) in every file of the project (depending on the kind of change).
I have a fix up in #28028 to avoid iterating every file.

[thekiba]

I build typescript from your pull request, and used it to build my application. Now the build time is the same as before.

👍Thanks for the quick response.

[zorrme]

Can we release this please ?

[DanielRosenwasser]

This should be available in TypeScript 3.1.6. Thanks @ajafff!

[Manish3177]

Could we get updated VS installer for 3.1.6: https://www.microsoft.com/en-us/download/details.aspx?id=55258?

[Manish3177]

Pinging again. It's not obvious how to apply the contents of 3.1.6 source on top of the installer linked above. Is it just a matter of copying over and overriding tsc.js+tsc.exe? Is there anything else that needs to be copied over? At the very least, I'd like to hear from one of the devs that it won't break anything. A diff of tsc.js between the two version really lights up because the source contains comments.