[BUG] Clearing selector logging configuration leaves the previous sampler active #7750

Current behavior

AbstractLogPluginDataHandler.handlerSelector() returns immediately for an empty or {} selector handle, leaving the previous SELECT_API_CONFIG_MAP entry intact. LogCollectConfigUtils.isSampled() prefers that entry's sampler, so clearing the override does not restore global/default sampling.

Locations / trigger

• AbstractLogPluginDataHandler.java:124–138
• LogCollectConfigUtils.java:106–114

Set global sampling to 0, configure selector sampling to 1, then update the selector handle to {}. The old always-sample entry remains. The reverse transition can also leave logging suppressed when operators expect fallback to a nonzero global rate.

Reproduction / validation

A Java probe compiled the current abstract logging handler and configuration utility. A concrete no-I/O subclass exercised actual handlerSelector()/isSampled() calls, with a global never-sample control:

SELECTOR_1_GLOBAL_0 sampled=true
AFTER_CLEAR sampled=true selectorEntry=true
REMOVE_CONTROL sampled=false

removeSelector() is the passing control demonstrating that removal restores global sampling. A separate reviewer independently confirmed the stale-map path. No backend log delivery or provider credentials were involved.

Impact / expected behavior

Runtime logging can continue at a stale selector rate indefinitely after a configuration clear, producing unexpected volume or missing expected records. Clearing a selector override should remove it or otherwise resolve sampling from the current global configuration.

Suggested fix

Remove the selector-specific config on empty/{} updates and audit overrides that bypass this generic handler. Preserve applicable backend-client teardown without conflating sampling-map cleanup with client resource ownership.

Related existing work

#7455 concerns re-enabling a stopped collector; #7454 concerns RabbitMQ selector-client recreation; #7686 concerns JVM-shutdown cleanup; #7687 concerns queue-drop metrics. This issue reproduces stale selector sampling after clearing configuration, independently of collector start/stop or queue behavior. Complete-title, open-PR and live sampling searches found no matching report.

Reviewed revision

Apache ShenYu 2.7.2-SNAPSHOT, master@66d7d954ca37d651a5ad916f988a8081157a7ab4. P2 / Medium, high confidence. Unit-test and CI issue categories excluded.