RFR: 8074101: Add verification that all tasks are actually claimed during roots processing [v4]

[Kim Barrett]

On Wed, 13 Jan 2021 10:20:12 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> The first commit removes some obsolete enum items, while the second commit adds the verification logic. Commit 2 introduces some "empty" task claims for the verification logic, explicitly marked in the comments.
>> 
>> Test: hotspot_gc
>
> Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   review

Marked as reviewed by kbarrett (Reviewer).

src/hotspot/share/gc/shared/workgroup.hpp line 331:

> 329: 
> 330:   // The calling thread asserts that it has attempted to claim all the tasks
> 331:   // that it will try to claim.  Tasks that is meant to be skipped must be

s/is meant/are meant/

src/hotspot/share/gc/shared/workgroup.hpp line 332:

> 330:   // The calling thread asserts that it has attempted to claim all the tasks
> 331:   // that it will try to claim.  Tasks that is meant to be skipped must be
> 332:   // explicitly passed as extra arguments using the variadic version below.

I would drop "using the variadic version below".  I think of this as a function that takes some optional "these are expected to be skipped" task designators, and the non-variadic overload is just an implementation detail to handle the base case of there being none of those.

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PR: https://git.openjdk.java.net/jdk/pull/2046