Use timed wait to sleep control thread

[earthling-amzn]

Using a timed wait rather than a naked sleep allows the control thread to be more responsive to requests from mutators and the regulator thread to start GC cycles. The sleep time is also changed from ShenandoahControlIntervalMin to ShenandoahControlIntervalMax to reduce unnecessary polling cycles. We could use a plain wait, but the control thread is responsible for periodically sending allocation metrics to the pacer.

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Progress

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Reviewers

• Aleksey Shipilev (@shipilev - Reviewer) ⚠️ Review applies to f4b5090

Reviewing

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[mlbridge]

Webrevs

• 02: Full - Incremental (16d39268)
• 01: Full - Incremental (f4b50907)
• 00: Full (69650c28)

[rkennke]

This looks like something that @shipilev has touched a few times before.

[shipilev]

I don't mind this going into sandbox, but honestly, we need to fix it in the mainline. The awkwardness of control loop sleep-looping gets very tedious.

[openjdk]

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Use timed wait to sleep control thread

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[shipilev]

I shall try and do this in mainline with this: https://bugs.openjdk.java.net/browse/JDK-8264851 -- probably next week, though.

[shipilev]

Oh wait, questions...

[earthling-amzn]

I'm not sure we can fix this so easily on mainline. The control thread on mainline needs to periodically evaluate the heuristics. To support the generational changes, heuristic evaluation was moved to a separate thread (so that it can initiate a young collection while the control thread is busy handling an old collection). A timed wait would still work on mainline, but an infinite wait would keep the heuristics from being evaluated.

[shipilev]

OK then, with one minor stylistic nit.

[shipilev]

Good to go.

[earthling-amzn]

/integrate

[shipilev]

/sponsor

[shipilev]

OpenJDK infra seems to be at maintenance. Bots would hopefully integrate as infra is online again.

[openjdk]

@earthling-amzn
Your change (at version 16d3926) is now ready to be sponsored by a Committer.

[openjdk]

@shipilev @earthling-amzn Pushed as commit 84bb2c3.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

[earthling-amzn]

OpenJDK infra seems to be at maintenance. Bots would hopefully integrate as infra is online again.

Yay bots!