Iterate on DLM Transition service

[lukewhiting]

This makes a few improvements to the DLM transition service:

• Add a queue to the executor to allow more indices than worker threads to be submitted for conversion, preventing wasted time between threads becoming available and the next loop through the marked indices
• Switches to using the ESExecutors daemon thread factory, removing the need to declare thread management capabilities in this plugin
• Wraps the executor's thread factory so the index name is appended to the thread name
• Tracks running transitions in a map (Currently just a bool for is running or is queued) but could later be expanded to be an enum or alike to track more detailed progress / state.
• Fixes relevant tests in both the executor and service to account for the new queue

[lukewhiting]

@coderabbitai review

[coderabbitai]

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[elasticsearchmachine]

Pinging @elastic/es-storage-engine (Team:StorageEngine)

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR refactors the DLM frozen transition executor to implement bounded-queue task scheduling. It replaces set-based running-state tracking with a concurrent map that tracks both queued and active transitions by index name, adds a configurable maxQueueSize setting (default 500), and configures the thread pool with a bounded queue matching that size. Capacity checks now account for both active concurrency and queue depth. The executor constructor signature changes to accept maxQueueSize, and transition tracking methods are renamed from isTransitionRunning to transitionSubmitted. The entitlement policy is simplified by removing an unnecessary permission entry.

Possibly related PRs

• Add new DLM Frozen Tier Transition execution plugin and service #144595: Modifies the same dlm-frozen-transition components including executor task tracking, constructor signatures, service-level queue and thread-pool configuration, and corresponding test updates.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

• 🛠️ Update Documentation: Commit on current branch
• 🛠️ Update Documentation: Create PR

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[coderabbitai]

🧹 Nitpick comments (1)

x-pack/plugin/dlm-frozen-transition/src/main/java/org/elasticsearch/xpack/dlm/frozen/DlmFrozenTransitionExecutor.java (1)

50-56: Thread name customization won't work as intended.

The r instanceof DlmFrozenTransitionRunnable check will always be false—by the time the thread factory receives r, it's wrapped in executor infrastructure (e.g., FutureTask), not the original task.

Not a merge blocker—functionality is correct, just thread names won't include the index.

Alternative: Pass index name via ThreadLocal or remove the dead code

If index-specific thread names are important, consider a ThreadLocal<String> set in wrapRunnable() and read in the thread factory. Otherwise, this block can be removed since it never executes.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In
`@x-pack/plugin/dlm-frozen-transition/src/main/java/org/elasticsearch/xpack/dlm/frozen/DlmFrozenTransitionExecutor.java`
around lines 50 - 56, The thread-name customization block inside the
EsExecutors.newFixed factory doesn't work because the runnable handed to the
thread factory is wrapped (e.g., FutureTask), so the `r instanceof
DlmFrozenTransitionRunnable` check never matches; either remove that dead branch
or implement the suggested ThreadLocal approach: set a ThreadLocal<String>
(e.g., in DlmFrozenTransitionExecutor.wrapRunnable or where
DlmFrozenTransitionRunnable is wrapped) with dftr.getIndexName() before wrapping
and clear it after, then read that ThreadLocal in the thread factory used by
EsExecutors.newFixed (EXECUTOR_NAME) to append the index to thread.getName();
reference DlmFrozenTransitionRunnable, wrapRunnable(),
EsExecutors.newFixed/EXECUTOR_NAME and the thread factory to locate the change.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In
`@x-pack/plugin/dlm-frozen-transition/src/main/java/org/elasticsearch/xpack/dlm/frozen/DlmFrozenTransitionExecutor.java`:
- Around line 50-56: The thread-name customization block inside the
EsExecutors.newFixed factory doesn't work because the runnable handed to the
thread factory is wrapped (e.g., FutureTask), so the `r instanceof
DlmFrozenTransitionRunnable` check never matches; either remove that dead branch
or implement the suggested ThreadLocal approach: set a ThreadLocal<String>
(e.g., in DlmFrozenTransitionExecutor.wrapRunnable or where
DlmFrozenTransitionRunnable is wrapped) with dftr.getIndexName() before wrapping
and clear it after, then read that ThreadLocal in the thread factory used by
EsExecutors.newFixed (EXECUTOR_NAME) to append the index to thread.getName();
reference DlmFrozenTransitionRunnable, wrapRunnable(),
EsExecutors.newFixed/EXECUTOR_NAME and the thread factory to locate the change.

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ℹ️ Review info

⚙️ Run configuration

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Run ID: ef209135-e37f-45a3-b4ce-0ba669b69dcd

📥 Commits

Reviewing files that changed from the base of the PR and between a7e2068 and 953b929.

📒 Files selected for processing (6)

• x-pack/plugin/dlm-frozen-transition/src/main/java/org/elasticsearch/xpack/dlm/frozen/DlmFrozenTransitionExecutor.java
• x-pack/plugin/dlm-frozen-transition/src/main/java/org/elasticsearch/xpack/dlm/frozen/DlmFrozenTransitionPlugin.java
• x-pack/plugin/dlm-frozen-transition/src/main/java/org/elasticsearch/xpack/dlm/frozen/DlmFrozenTransitionService.java
• x-pack/plugin/dlm-frozen-transition/src/main/plugin-metadata/entitlement-policy.yaml
• x-pack/plugin/dlm-frozen-transition/src/test/java/org/elasticsearch/xpack/dlm/frozen/DlmFrozenTransitionExecutorTests.java
• x-pack/plugin/dlm-frozen-transition/src/test/java/org/elasticsearch/xpack/dlm/frozen/DlmFrozenTransitionServiceTests.java

💤 Files with no reviewable changes (1)

• x-pack/plugin/dlm-frozen-transition/src/main/plugin-metadata/entitlement-policy.yaml

[dakrone]

LGTM, I left some minor comments, but nothing blocking. Thanks for working on this Luke!

[seanzatzdev]

LGTM, thanks!