docs(clustering): correct the stale server-heartbeat interval comment

[dsolistorres]

Proposed Changes

Fixes #37015.

SERVER_HEARTBEAT_RUN_EVERY_SECONDS defaults to 60, but the trailing comment read // runs every 5 seconds.

-       final int delaySeconds = Config.getIntProperty("SERVER_HEARTBEAT_RUN_EVERY_SECONDS", 60); // runs every 5 seconds.
+       // Both default to one minute, matching the HEARTBEAT_CRON_EXPRESSION (0 0/1 * * * ?) this
+       // replaced when the schedulers were unified. The cadence bounds how quickly a node notices
+       // a cluster membership change or retries a failed cache-transport rewire.
+       final int delaySeconds = Config.getIntProperty("SERVER_HEARTBEAT_RUN_EVERY_SECONDS", 60);

Why it was wrong

Not a default that changed and left the comment behind — the comment was wrong when it was written.

999036092e (#19291, unifying the 3 quartz schedulers, Oct 2020) created this block by adapting the SystemEventsJob block ~150 lines above:

final int delaySeconds = Config.getIntProperty("SYSTEM_EVENTS_DELAY_SECONDS", 5); // runs every 5 seconds.

That one is correct — it really does default to 5. The heartbeat copy changed the property name and the default to 60 and kept the comment verbatim.

The cadence never changed either. Before that commit the heartbeat was a Quartz CronTrigger on HEARTBEAT_CRON_EXPRESSION, defaulted to 0 0/1 * * * ? in dotcms-config-cluster.properties — once a minute. The 60-second fixed delay preserved it; only the mechanism changed.

Testing

Comment only, no behaviour change — nothing to test. Found while tracing the heartbeat cadence for #36803, where this interval bounds how quickly a failed cache-transport rewire is retried.

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[claude]

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Code Review

• Read the diff and surrounding context in DotInitScheduler.java
• Verify the comment matches actual code behavior

New Issues

No issues found.

This is a comment-only change with no behavior impact. The correction is accurate:

• DotInitScheduler.java:583 — SERVER_HEARTBEAT_INITIAL_DELAY_SECONDS defaults to 60
• DotInitScheduler.java:587 — SERVER_HEARTBEAT_RUN_EVERY_SECONDS defaults to 60

Both defaults are 60 seconds, so "Both default to one minute" is correct, and the old // runs every 5 seconds. was indeed wrong. The new comment also usefully documents why the cadence matters (cluster membership detection + cache-transport rewire retry bound), which is a genuine improvement over a bare value restatement.

Nothing to test — no runtime path changed.
· fix-stale-heartbeat-interval-comment