8270870: Simplify G1ServiceThread

[kimbarrett]

Please review this simplification of the internal control structure of
G1ServiceThread, particularly around the entry and exit of monitor contexts.

In addition, the run_task logging now includes the delay between the
scheduled time to run and the actual, as that seems like useful information
to have sometimes.

I also changed the monitor rank from nonleaf to leaf. There was no reason
to use nonleaf, and leaf avoids questions about why nonleaf was used.

Testing:
mach5 tier1-3. This includes the gtest for G1ServiceThread.

Ran a test program with gc+task logging enabled and checked that the logging
output looked okay.

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JDK-8270870: Simplify G1ServiceThread

Reviewers

• Thomas Schatzl (@tschatzl - Reviewer) ⚠️ Review applies to 1a2e4e1
• Ivan Walulya (@walulyai - Committer) ⚠️ Review applies to 1a2e4e1

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/jdk pull/4868/head:pull/4868
$ git checkout pull/4868

Update a local copy of the PR:
$ git checkout pull/4868
$ git pull https://git.openjdk.java.net/jdk pull/4868/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 4868

View PR using the GUI difftool:
$ git pr show -t 4868

Using diff file

Download this PR as a diff file:
https://git.openjdk.java.net/jdk/pull/4868.diff

[bridgekeeper]

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[openjdk]

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[mlbridge]

Webrevs

• 01: Full - Incremental (bd364d33)
• 00: Full (1a2e4e18)

[tschatzl]

Lgtm.

[openjdk]

@kimbarrett This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8270870: Simplify G1ServiceThread

Reviewed-by: tschatzl, iwalulya

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 2 new commits pushed to the master branch:

• 8c8e3a0: 8271163: G1 uses wrong degree of MT processing since JDK-8270169
• 8a789b7: 8263840: PeriodicTask should declare its destructor virtual

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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[walulyai]

Lgtm!

[kimbarrett]

Thanks @tschatzl and @walulyai for reviews.

[kimbarrett]

/integrate

[openjdk]

Going to push as commit 0cc4bb7.
Since your change was applied there have been 2 commits pushed to the master branch:

• 8c8e3a0: 8271163: G1 uses wrong degree of MT processing since JDK-8270169
• 8a789b7: 8263840: PeriodicTask should declare its destructor virtual

Your commit was automatically rebased without conflicts.

[openjdk]

@kimbarrett Pushed as commit 0cc4bb7.

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