[8u] RFR: Backport of JDK-8222670: pathological case of JIT recompilation and code cache bloat

[Andrew John Hughes]

On 16/05/2019 18:23, Liu, Xin wrote:
> Hi, Reviewers,
> 
> Could you review this backport patch?
> 
> BUG: https://bugs.openjdk.java.net/browse/JDK-8222670
> Webrev: https://cr.openjdk.java.net/~xliu/8222670/webrev.8u-dev/
> 
> I can’t cleanly apply the original patch to jdk8u.  I made the following changes.
> 
>   1.  Include JDK-8223537.  It solved suspend problem in blocking mode. One line change.

I think this should be applied as a pre-requisite clean backport. Just
flag the bug with jdk8u-fix-request, no need for a separate review.

>   2.  Shorter wait period.  Otherwise, it’s easy to timeout for the  test.  It’s part of a JDK-8066770.
> https://cr.openjdk.java.net/~xliu/8222670/webrev.8u-dev/test/compiler/whitebox/CompilerWhiteBoxTest.java.udiff.html
> 

8066770 relies on a lot of WhiteBox API that is not present in 8u so I'm
ok with including just this segment.

>   1.  +1 for Tier4MinInvocationThreshold and Tier4CompileThreshold. Otherwise, we have to backport JDK-8059604, which looks like complicated.
> 
> https://cr.openjdk.java.net/~xliu/8222670/webrev.8u-dev/src/share/vm/prims/whitebox.cpp.udiff.html

JDK-8059604 looks backportable, but I'm ok with including this commented
workaround for now.

There seem to be two other changes being included here:

1. compileBroker.cpp changes

These aren't in the original JDK-8222670. In 9, the != NULL test is
added by "8144964: JVMCI compilations need to be disabled until the
module system is initialized". 8 has neither JVMCI or a module system,
so not sure why this test is being added here. Why is this included?

2. skiponTieredCompilation in CompilerWhiteBoxTest.java

This is part of "8059575: JEP-JDK-8043304: Test task: Tiered Compilation
level transition tests" which should also be backported as a pre-requisite.

> Thanks,
> --lx
> 

Thanks,
-- 
Andrew :)

Senior Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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