Integrated: JDK-8317987: C2 recompilations cause high memory footprint

[Thomas Stuefe]

On Thu, 12 Oct 2023 08:15:12 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> While playing with the new compiler memory statistic (https://github.com/openjdk/jdk/pull/16076), I saw that +StressRecompile causes a twofold increase in memory used during compilations. 
> 
> #### Baseline: 
> 
> highest peak during compilation is ~60 MB, caused by compilation of `java/lang/invoke/LambdaForm$Kind::<clinit>` with ~18k nodes.
> 
> `./images/jdk/bin/java -XX:CompileCommand='collectmemstat,*.*' -XX:-StressRecompilation -Xcomp -Xbatch -cp $REPROS_JAR de.stuefe.repros.Simple`
> 
> 
> total     NA        RA        #nodes  time    type  #rc thread              method
> (3/1425)
> 59063K    13406K    40025K    18345   6,174   c2    2   0x00007fdc2c28e7b0  java/lang/invoke/LambdaForm$Kind::<clinit>(()V) 
> 
> 
> #### +StressRecompile: 
> 
> highest peak during compilation is ~112 MB, same method, sameish node count.
> 
> `./images/jdk/bin/java -XX:CompileCommand='collectmemstat,*.*' -XX:+StressRecompilation -Xcomp -Xbatch -cp $REPROS_JAR de.stuefe.repros.Simple`
> 
> 
> total     NA        RA        #nodes  time    type  #rc thread              method
> (16/1434)
> 112M      13469K    94987K    18791   16,451  c2    2   0x00007f790428e7b0  java/lang/invoke/LambdaForm$Kind::<clinit>(()V) 
> 
> 
> 60M -> 112M. In both cases, a large part of the memory was allocated in resource areas. Its relative size compared to the total spike size increased. We accrue a lot of memory in ResourceArea over recompilations.
> 
> The solution is to wrap the `Compile` instantiation into a resource mark. Now we are at 61 MB, which is almost baseline:
> 
> 
> total     NA        RA        #nodes  time    type  #rc thread              method
> (3/1430)
> 61203K    13469K    40791K    18791   17,013  c2    2   0x00007fdf7428e7b0  java/lang/invoke/LambdaForm$Kind::<clinit>(()V)

This pull request has now been integrated.

Changeset: c88b3878
Author:    Thomas Stuefe <stuefe at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/c88b387881a6e9206f9804b4ca966334c65c008a
Stats:     1 line in 1 file changed: 1 ins; 0 del; 0 mod

8317987: C2 recompilations cause high memory footprint

Reviewed-by: adinn, kvn

-------------

PR: https://git.openjdk.org/jdk/pull/16161