Space: Cache isSubspace for a 3000% speedup

[dwijnand]

No description provided.

[dwijnand]

Who's interested and/or good at performance? I've seen commits and hears @odersky speak about doing some. Also @liufengyun might have some feedback specific to the space engine in general. Review feedback welcome.

[liufengyun]

It's nice to improve performance 👍 I'd suggest adding the test to benchmarks, and also run a bench test to see how it helps existing bench tests related to exhaustivity.

[dwijnand]

I'd suggest adding the test to benchmarks

I've not looked at the benchmarks? What am I adding and how? And is that instead of the existing test or in addtion?

also run a bench test to see how it helps existing bench tests related to exhaustivity

Do I need to have write access to the staging repo to create a branch there to do that still? And what's the next step after that? Sorry... this would be my first time playing the benchmarking game in the dotty repo.

[liufengyun]

I'd suggest adding the test to benchmarks

I've not looked at the benchmarks? What am I adding and how? And is that instead of the existing test or in addtion?

also run a bench test to see how it helps existing bench tests related to exhaustivity

Do I need to have write access to the staging repo to create a branch there to do that still? And what's the next step after that? Sorry... this would be my first time playing the benchmarking game in the dotty repo.

You can add a new exhaustivity check benchmark in the following file:

https://github.com/lampepfl/dotty/blob/master/bench/profiles/exhaustivity.yml

And then tell the bot to run the bench test with a comment like test performance with #exhaustivity please. When the test finishes, the bot will send a link to the test result.

I'm not sure if you need to push to staging repo (you can first try without doing that). You will definitely need to add yourself to be known to the bot here:

https://github.com/lampepfl/bench/blob/master/bin/process#L22

[bishabosha]

test performance with #exhaustivity please

[liufengyun]

It seems the Bot is not running, the same in #13715

[anatoliykmetyuk]

test performance with #exhaustivity please

[dottybot]

performance test scheduled: 1 job(s) in queue, 1 running.

[dottybot]

Performance test finished successfully:

Visit https://dotty-bench.epfl.ch/13637/ to see the changes.

Benchmarks is based on merging with master (1ed25ce)

[liufengyun]

The numbers look nice 👍

Regarding the implementation, I'd suggest trying caching the subtyping --- if the numbers are similar, caching for subtyping is better.

[dwijnand]

Regarding the implementation, I'd suggest trying caching the subtyping --- if the numbers are similar, caching for subtyping is better.

Caching the subtyping seems to be much worst:

$ qsc3 tests/pos/i13565.scala
[info] entering *experimental* thin client - BEEP WHIRR
[info] terminate the server with `shutdown`
> scalac -pagewidth 207  tests/pos/i13565.scala
[info] compiling 1 Scala source to /d/scala3/compiler/target/scala-3.1.1-RC1/classes ...
[info] running (fork) dotty.tools.dotc.Main -classpath /Users/dnw/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.6/scala-library-2.13.6.jar:/d/scala3/library/../out/bootstrap/scala3-library-bootstrapped/scala-3.1.2-RC1-bin-SNAPSHOT-nonbootstrapped/scala3-library_3-3.1.2-RC1-bin-SNAPSHOT.jar -pagewidth 207 tests/pos/i13565.scala
[success] Total time: 153 s (02:33), completed Dec 2, 2021 9:13:37 AM
$ git co .
Updated 1 path from the index
$ qsc3 tests/pos/i13565.scala
[info] entering *experimental* thin client - BEEP WHIRR
[info] terminate the server with `shutdown`
> scalac -pagewidth 207  tests/pos/i13565.scala
[info] compiling 1 Scala source to /d/scala3/compiler/target/scala-3.1.1-RC1/classes ...
[info] running (fork) dotty.tools.dotc.Main -classpath /Users/dnw/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.6/scala-library-2.13.6.jar:/d/scala3/library/../out/bootstrap/scala3-library-bootstrapped/scala-3.1.2-RC1-bin-SNAPSHOT-nonbootstrapped/scala3-library_3-3.1.2-RC1-bin-SNAPSHOT.jar -pagewidth 207 tests/pos/i13565.scala
[success] Total time: 7 s, completed Dec 2, 2021 9:14:56 AM

Happy to approve this?

[liufengyun]

LGTM 👍