RFR: 8293020: jmod should not be treated as "small" tool for large modules

[Erik Joelsson]

On Mon, 29 Aug 2022 10:13:29 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> This is similar to [JDK-8245168](https://bugs.openjdk.org/browse/JDK-8245168), but the blanket change to allow all modules be compiled with default options is a net loss. Instead, we can hand-pick the major offenders (large modules) where running jmod with normal tool options improves performance.
> 
> I instrumented the jmod to tell me the times it needs to create individual modules, and hand-picked three top modules that take multiple seconds to run.
> 
> Motivational `make clean-images images` times:
> 
> 
> # x86_64 Server, release
> 
> # Baseline
> real	0m12.040s
> user	1m4.872s
> sys	0m10.805s
> 
> # Patched
> real	0m10.785s  ; <--- 1.2s faster
> user	1m7.031s
> sys	0m10.985s
> 
> # x86_64 Server, fastdebug
> 
> # Baseline
> real	0m19.263s
> user	2m42.317s
> sys	0m18.537s
> 
> # Patched
> real	0m17.911s ;  <--- 1.1s faster
> user	2m52.810s
> sys	0m19.092s
> 
> 
> # x86_64 Server, slowdebug
> 
> # Baseline
> real	0m44.799s
> user	10m7.106s
> sys	0m17.578s
> 
> # Patched
> real	0m46.975s   ; <--- 2.5 sec slower
> user	11m1.155s
> sys	0m17.060s
> 
> 
> I think we can accept the `slowdebug` regression in favor of improvements on `release` and `fastdebug` that most people seem to be building every day.

Marked as reviewed by erikj (Reviewer).

make/CreateJmods.gmk line 232:

> 230: JMOD_SMALL_FLAGS=
> 231: ifeq ($(findstring $(MODULE), java.base java.desktop jdk.localedata), )
> 232:     JMOD_SMALL_FLAGS += $(JAVA_TOOL_FLAGS_SMALL)

Two space indent please, otherwise looks good.

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PR: https://git.openjdk.org/jdk/pull/10062