[jdk17u-dev] RFR: 8274753: ZGC: SEGV in MetaspaceShared::link_shared_classes

[Rui Li]

On Wed, 26 Jan 2022 07:40:03 GMT, Goetz Lindenmaier <goetz at openjdk.org> wrote:

>> Hi all,
>> 
>> not a clean backport. I had to fix up classLoaderData.cpp a bit because `SystemDictionaryShared::handle_class_unloading(ik);` does not yet exist in jdk17 and I did not want to bring the dependent cleanup change into jdk17 too (among other things because Oracle seems not to have done it either in their closed backport as far as I can glean from the JBS tags).
>> 
>> Tested in SAP nightlies for about a week now.
>> 
>> Thanks!
>
> src/hotspot/share/classfile/classLoaderData.cpp line 893:
> 
>> 891:       if (Arguments::is_dumping_archive()) {
>> 892:         SystemDictionaryShared::remove_dumptime_info(ik);
>> 893:       }
> 
> This is a part of handle_class_unloading(). I.e., you basically "undo" '8267189: Remove duplicated unregistered classes from dynamic archive'. That change replaced remove_dumptime_info() by handle_class_unloading() which calls remove_dumptime_info().
> And you add the check for is_dumping_archive() that was 
> added to handle_class_unloading() in 
> '8265602: -XX:DumpLoadedClassList should support custom loaders'.
> 
> LGTM

@GoeLin I'm backporting https://bugs.openjdk.org/browse/JDK-8267189 to 17 and found this comment. Having trouble understanding it. Is it still safe / recommended to backport JDK-8267189 with this unclean 8274753 backport? Thanks.

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PR: https://git.openjdk.org/jdk17u-dev/pull/118