RFR: 8237567: Refactor G1-specific code in shared VM_CollectForMetadataAllocation

[Thomas Schatzl]

On Fri, 27 Aug 2021 15:48:50 GMT, Ivan Walulya <iwalulya at openjdk.org> wrote:

> Hi all,
> 
> Please review this refactoring change to move G1 specific code out of VM_CollectForMetadataAllocation. 
> 
> Testing: Tier 1-3.

While not completely satisfying - maybe adding a predicate to `CollectedHeap` for this to completely remove the G1 dependency? - it's a step in the right direction. Adding more methods that are really specific to one GC are not really satisfying either, so lgtm from me.

Please fix the  method name `concurrent` vs. `conc` before pushing.

src/hotspot/share/gc/g1/g1CollectedHeap.hpp line 1137:

> 1135:   bool try_collect(GCCause::Cause cause, const G1GCCounters& counters_before);
> 1136: 
> 1137:   void initiate_conc_gc_for_metadata_allocation(GCCause::Cause gc_cause);

Please type out `concurrent` as other identifiers here do.

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Marked as reviewed by tschatzl (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5282