RFR: 8263108: Class initialization deadlock in java.lang.constant [v2]

[Chris Hegarty]

On Fri, 12 Mar 2021 13:23:39 GMT, Peter Levart <plevart at openjdk.org> wrote:

>> Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Follow Peter Levart's review suggestion - remove volatile
>
> This looks good to me. Maybe if you wanted the previous performance back (when the `cannonicalMap` field was static final and therefore JIT could constant-fold the Map instance), you could now annotate the field with `@Stable` annotation to allow JIT to produce similar code. I would also move the `Map.ofEntries(...)` expression into a separate private static method since I believe it has substantial bytecode size. `tryCanonicalize()` method bytecode size would then more likely fall below the inlining threshold.

What you have is probably fine, but has any consideration been given to using the initialization-on-demand holder idiom? e.g.

     static private class CanonicalMapHolder {
        static final Map<MethodHandleDesc, Function<DynamicConstantDesc<?>, ConstantDesc>> CANONICAL_MAP
              = Map.ofEntries(..);
     }

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PR: https://git.openjdk.java.net/jdk/pull/2893