Comments (2)
Do I understand it right? I just want to understand the whole picture more clearly since there's a bunch of race-condition issues happened recently.
- The "frequent" leadership switch is caused by ZK session expiration.
- What caused the "frequent" ZK session expiration?
- Why the new controller didn't successfully register the callback handlers?
- Is it because the 1st new controller hasn't finished the registration and it lost leadership already then the 2nd new controller came to place?
from helix.
Do I understand it right? I just want to understand the whole picture more clearly since there's a bunch of race-condition issues happened recently.
- The "frequent" leadership switch is caused by ZK session expiration.
Yes.
- What caused the "frequent" ZK session expiration?
This is not confirmed. Maybe GC, maybe network issue. Or combined. The result is obvious though.
- Why the new controller didn't successfully register the callback handlers?
Please refer to the fix. The previous design cannot handle more than one leader node change event in a graceful way.
This use case is just not considered.
- Is it because the 1st new controller hasn't finished the registration and it lost leadership already then the 2nd new controller came to place?
The 1st controller does lose the leadership, but that does not cause the problem. The issue was in one controller always. If this one has a leftover controller change event unprocessed, it will for sure fall into this bad situation.
from helix.
Related Issues (20)
- partitionAssignment fails for resources with ANY_LIVEINSTANCE replica count
- [Failed CI Test] testDisableErrorLogByDefault(org.apache.helix.util.TestStatusUpdateUtil) HOT 18
- API simplifcation
- Documentation
- Helix Gateway Service
- New Assignment / Rebalancer
- Correctness testing
- Scale testing
- [Failed CI Test] testSwapEvacuateAdd(org.apache.helix.integration.rebalancer.TestInstanceOperation) HOT 1
- Enable logging detailed and specific error message for WAGED Rebalance failures
- Support user-defined TaskAssignmentCalculator HOT 2
- [Failed CI Test] testSessionExpiryInTransition(org.apache.helix.integration.manager.TestParticipantManager) HOT 1
- Fix packaging of missing resources in JDK 1.8 (backward compatibile) helix jars
- [Failed CI Test] testGetAllInstances(org.apache.helix.rest.server.TestInstancesAccessor) HOT 7
- [Failed CI Test] testDisconnectWhenConnectionBreak(org.apache.helix.integration.TestZkConnectionLost) HOT 1
- [Failed CI Test] testGetMessagesByStateModelDef(org.apache.helix.rest.server.TestPerInstanceAccessor) HOT 7
- [Failed CI Test] testGetAllMessages(org.apache.helix.rest.server.TestPerInstanceAccessor) HOT 4
- Accessing HelixManager ExecutorService HOT 6
- Apache Pinot facing issues with Helix version 1.4.0 HOT 1
- [Failed CI Test] testLostZkConnection(org.apache.helix.integration.TestZkConnectionLost) HOT 1
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