RFC: Performance after upgrading from 25.2.1 to 25.3.0

[MykytaKryvenko]

Issue :

25.3.0 version is extremely slow compared to 25.2.x.
E.g. my previous test runs were 17s, and 135s after update.

[ahnpnl]

can you please provide more information ? Do you run with or without cache ? Did you clear cache after upgrading to 25.3.0 ?

[MykytaKryvenko]

I tried to run jest with --clearCache, did not help.

[ahnpnl]

from what I can see is, before upgrading probably your tests ran with cache. After upgrading, old cache becomes invalid so tests will need to cache again. That's why you saw a big difference. Several steps that you can help us to verify is:

• Clear cache
• Run tests with --no-cache for 25.2.1
• Clear cache again
• Run tests with --no-cache for 25.3.0

If the amount of time tests take is the same for these above steps, it means no downgrade

[MykytaKryvenko]

Thank you for the suggestion, but it did not help as well :(
After all steps and running with no-cache it takes ~270s to finish.

[ahnpnl]

Hmm I don’t see any issues on my side. Also confirmed from #1450 (comment)

[ahnpnl]

Any chances to have your repo to try out ?

[MykytaKryvenko]

Unfortunately no.
We have pinned version for now. Maybe someone else will face this issue too.

[bmesuere]

Maybe it's related but moving to 25.3.0, it seems that a lot more files are getting compiled. We use this in a rails project and are now getting a bunch of errors like error TS5055: Cannot write file '/<<path>>/config/webpack/development.js' because it would overwrite input file. which suggests it now handles every js file in repository.

[ahnpnl]

Maybe it's related but moving to 25.3.0, it seems that a lot more files are getting compiled. We use this in a rails project and are now getting a bunch of errors like error TS5055: Cannot write file '/<<path>>/config/webpack/development.js' because it would overwrite input file. which suggests it now handles every js file in repository.

thanks for your feedback. Do you use allowJs in your repo ?

[bmesuere]

yes, I do. After checking the other issues, I think #1472 will probably resolve the error for me.

[ahnpnl]

Thanks. Probably the issue is bigger than just the fix #1472 as you mentioned that there are more files getting compile. That is a useful hint to solve this issue.

Up til now, imo #1472 is just a workaround and there should be a proper fix.

[MykytaKryvenko]

I want to add that we are using allowJs too, without it compilation fails for 25.3.0, but works for 25.2.1