RFR: 8280041: Retry loop issues in java.io.ClassCache [v3]

[Peter Levart]

On Wed, 19 Jan 2022 08:25:55 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> JDK-8277072 introduced java.io.ClassCache, but there seem to be at least two issues with it:
>>   - The cache cannot disambiguate between cleared SoftReference and the accidental passing of `null` value; in that case, the retry loop would spin indefinitely;
>>   - If retry loop would spin several times, every time discovering a cleared SoftReference, it would create and register new SoftReference on the ReferenceQueue. However, it would not *drain* the RQ in the loop; in that case, we might have the unbounded garbage accumulating in RQ; 
>> 
>> Attention @rkennke, @plevart.
>> 
>> Additional testing:
>>   - [x] Linux x86_64 fastdebug `java/io/ObjectStreamClass`
>>   - [x] Linux x86_64 fastdebug `tier1`
>>   - [x] Linux x86_64 fastdebug `tier2`
>>   - [x] Linux x86_64 fastdebug `tier3`
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Test summary

Hi,
Sorry for late join. I'm monitoring core-libs-dev mailing list and didn't see the message there. I stumbled on this PR accidentally...

I just have one comment.

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Changes requested by plevart (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/7092