[BUG] Cluster master election scheduler can stop after one renewal exception

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
78/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Quiet
Tech stack
java
Domain
backend, distributed-systems

Research direction

Start by reading shenyu-admin/src/main/java/org/apache/shenyu/admin/mode/cluster/service/ShenyuClusterService.java, focusing on startSelectMasterTask() and doSelectMaster(). Trace how the scheduled task handles renewal exceptions; done means errors are logged without terminating future scheduled election attempts.

Written by the indexing model from the issue text.

Description

Current Behavior

Cluster master election/renewal can stop permanently after one exception escapes the scheduled task.

ShenyuClusterService.startSelectMasterTask() schedules master selection with scheduleAtFixedRate(...):

executorService.scheduleAtFixedRate(() -> doSelectMaster(host, port, contextPath), ...);

doSelectMaster() catches exceptions, closes the check services, and then throws a new ShenyuException:

} catch (Exception e) {
    LOG.error("select master error", e);
    upstreamCheckService.close();
    instanceCheckService.close();
    throw new ShenyuException(...);
}

For ScheduledThreadPoolExecutor, an exception escaping a fixed-rate task suppresses later executions of that periodic task. A transient lock/renewal failure can therefore stop future master selection attempts in that process.

Expected Behavior

Master election/renewal errors should be logged and the next scheduled election attempt should still run. Exceptions should not escape the periodic scheduler task.

Impact

After a transient cluster backend failure, the admin node may stop participating in master election until it is restarted.

Code Location
  • shenyu-admin/src/main/java/org/apache/shenyu/admin/mode/cluster/service/ShenyuClusterService.java
    • startSelectMasterTask() schedules the periodic task.
    • doSelectMaster() rethrows from the catch block.
Dominant language
Java
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