RFR: 8255235: ZGC: Allocate and initialize forwarding data structures in parallel [v4]

[Erik Österlund]

On Wed, 28 Oct 2020 10:40:33 GMT, Per Liden <pliden at openjdk.org> wrote:

>> As a continuation of JDK-8255234, we can speed things up even more by allocating/initializing forwarding data structures in parallel. For example, testing using BigRamTester shows the time for "Concurrent Select Relocation Set" phase drop by ~50% when using 4 threads.
>> 
>> This PR depends on "8255234: ZGC: Bulk allocate forwarding data structures", which is a separate PR (https://github.com/openjdk/jdk/pull/804).
>
> Per Liden has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:
> 
>  - Merge master
>  - Add assert
>  - Merge
>  - Assert that all allocated memory is used
>  - Merge
>  - Assert that allocations never fail
>  - 8255235: ZGC: Allocate and initialize forwarding data structures in parallel
>  - 8255234: ZGC: Bulk allocate forwarding data structures

Looks good.

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Marked as reviewed by eosterlund (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/805