fix(registry-nacos): guard lazy scheduler creation in NacosRegistry with double-checked locking - #16462
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Lubaoshuai wants to merge 1 commit into
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fix(registry-nacos): guard lazy scheduler creation in NacosRegistry with double-checked locking#16462Lubaoshuai wants to merge 1 commit into
Lubaoshuai wants to merge 1 commit into
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…ith double-checked locking scheduleServiceNamesLookup performed an unsynchronized check-then-act on the scheduledExecutorService field. Concurrent admin-protocol subscribes could each create their own single-thread executor; only the last assigned reference is shut down in shutdownServiceNamesLookup, leaking non-daemon scheduler threads that keep polling Nacos forever and block JVM exit. Create the executor under double-checked locking, publish it after the task is scheduled, and use a named daemon thread factory. Fixes apache#15886
Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## 3.3 #16462 +/- ##
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+ Coverage 60.91% 60.97% +0.05%
- Complexity 15 11774 +11759
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Files 1953 1953
Lines 89271 89275 +4
Branches 13473 13474 +1
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+ Hits 54383 54436 +53
+ Misses 29309 29256 -53
- Partials 5579 5583 +4
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What is the purpose of the change
Concurrent admin-protocol subscriptions can leak non-daemon scheduler threads in NacosRegistry.
scheduleServiceNamesLookupperforms an unsynchronized check-then-act on thescheduledExecutorServicefield: two concurrentsubscribecalls withprotocol=admin(e.g. multiple Dubbo Admin/ops clients) can both observenulland each create their own single-thread scheduled executor.shutdownServiceNamesLookup()only shuts down the last assigned reference, so every racing duplicate executor keeps pollinggetAllServiceNames()forever. The default thread factory also creates non-daemon threads, so the leaked schedulers block JVM exit.Brief changelog
Dubbo-Nacos-Registry-Scheduler) so leaks, if any, are identifiable in thread dumps and cannot block shutdown.Verifying this change
NacosRegistryTest.testConcurrentAdminSubscribeCreatesSingleDaemonScheduler: 8 concurrent admin-protocol subscribes against a mock NamingService assert exactly one scheduler thread exists, it is a daemon, and it terminates afterunsubscribe.mvn -pl dubbo-registry/dubbo-registry-nacos -am test -Dtest=NacosRegistryTestpasses (6/6).Fixes #15886