RFR: 8274033: Some tier-4 CDS EpsilonGC tests throw OOM

[David Holmes]

On Wed, 22 Sep 2021 05:44:44 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> Problem:
> 
> In Oracle hs-tier4, in order to test the support of archived heap objects in EpsilonGC, we run all test cases under open/test/hotspot/jtreg/runtime/cds with `-Dtest.cds.runtime.options=-XX:+UnlockExperimentalVMOptions,-XX:+UseEpsilonGC`. Some of those tests may create a lot of objects, some of those will eventually become unreferenced. Because EpsilonGC cannot collect garbage, the tests will fail with OOM.
> 
> Fix:
> 
> Limit the set of tests to be executed by introducing a test group `hotspot_cds_epsilongc`. This reduces the number of tests from 200+ to about 50. The problematic `runtime/cds/appcds/methodHandles` cases are excluded.

Hi Ioi,

The changes to the test files seem unrelated to the current issue. ??

The group change seems okay but please add a comment.

Thanks,
David

test/hotspot/jtreg/TEST.groups line 402:

> 400:   runtime/cds/appcds/sharedStrings/SharedStringsBasic.java
> 401: 
> 402: hotspot_cds_epsilongc = \

I don't know why we don't comment groups in this file but please add a comment here that these are low-memory using tests that won't fail (with a reasonable heap size) when run with a fake GC.

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Changes requested by dholmes (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5626