8338534: Shenandoah: Handle alloc failure differently when immediate garbage is available

[earthling-amzn]

This change creates separate monitors for threads waiting because of an allocation failure and threads waiting for a complete gc cycle (this is as things are on master). The respective monitors are acquired on different code paths (request_gc, handle_alloc_failure, handle_alloc_failure_full). Separating them like this avoids spurious wakeups from incomplete old marking increments (which neither free up memory nor complete a cycle). It also allows alloc failure waiters to be woken up midcycle after final mark reclaims immediate garbage without also waking up threads waiting for a complete cycle. Finally, this change consolidates several methods duplicated between ShControlThread and ShGenerationalControlThread into their ShController base class.

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Progress

• Change must not contain extraneous whitespace
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Integration blocker

 ⚠️ Dependency #31797 must be integrated first

Issue

• JDK-8338534: Shenandoah: Handle alloc failure differently when immediate garbage is available (Enhancement - P4)

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[bridgekeeper]

👋 Welcome back wkemper! A progress list of the required criteria for merging this PR into pr/31797 will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

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[openjdk]

@earthling-amzn The following labels will be automatically applied to this pull request:

• hotspot-gc
• shenandoah

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[openjdk]

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[mlbridge]

Webrevs

• 01: Full - Incremental (c55e03c3)
• 00: Full (1b23c753)