RFR: 8300926: Several startup regressions ~6-70% in 21-b6 all platforms [v4]

[Daniel D. Daugherty]

On Wed, 22 Feb 2023 06:26:55 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Robbin Ehn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Coleen fix
>
> src/hotspot/share/classfile/systemDictionary.cpp line 1620:
> 
>> 1618:     assert(k != nullptr, "just checking");
>> 1619:     if (Universe::is_fully_initialized()) {
>> 1620:       assert_locked_or_safepoint(Compile_lock);
> 
> This serves no purpose given you just took out the lock. But it does raise the question as to whether the lock can/should always be taken out if called at a safepoint, or if the Universe is not yet fully initialized?

I found one call to `add_to_hierarchy()` where we previously did not
grab in `Compile_lock` in `vmClasses::resolve_shared_class()` and
that call is made with this assert in place:
```assert(!Universe::is_fully_initialized(), "We can make short cuts only during VM initialization");```

so it looks to me like we have a locking issue there (as in too early for locks).

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PR: https://git.openjdk.org/jdk/pull/12585