Details
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Bug
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Status: Resolved
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Critical
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Resolution: Fixed
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1.8.0
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None
Description
Scenario
- Start a brand-new cluster with only 1 node (nifi0). Using existing multi-node clusters don't reproduce the issue.
- Create GenerateFlowFile -> LogAttribute
- Then set 'Partition by attribute' LB strategy at the connection
- Add 2nd node, nifi1
- Generate some FlowFiles. Then load-balance activity never finishes.
With a 2-node cluster, for some reason, each node ended up having different queuePartitions order at SocketLoadBalancedFlowFileQueue. By adding debug logs, I found each node has followings:
- nifi0
- queuePartitions[0} = RemoteQueuePartition[queueId=14ac9634-0166-1000-ffff-ffffd9ae7f4b, nodeId=nifi1.example.com:8080]
- queuePartitions[1} = SwappablePriorityQueueLocalPartition[queueId=14ac9634-0166-1000-ffff-ffffd9ae7f4b]
- nifi1
- queuePartitions[0} = RemoteQueuePartition[queueId=14ac9634-0166-1000-ffff-ffffd9ae7f4b, nodeId=nifi0.example.com:8080]
- queuePartitions[1} = SwappablePriorityQueueLocalPartition[queueId=14ac9634-0166-1000-ffff-ffffd9ae7f4b]
Because of this, 'Partition by attribute' LB strategy keeps re-partitioning received FlowFiles between each other in case the calculated attribute value hash points to queuePartitions[0]. Following log is written endlessly:
2018-10-05 07:09:32,372 DEBUG [Load Balance Server Thread-3] o.a.n.c.q.c.SocketLoadBalancedFlowFileQueue Received the following FlowFiles from Peer: ...offset=7452, length=180],offset=162,name=10653317458635,size=18]]. Will re-partition FlowFiles to ensure proper balancing across the cluster.
SocketLoadBalancedFlowFileQueue maintains queuePartitions by listening to cluster topology change using ClusterTopologyEventListener. SocketLoadBalancedFlowFileQueueClusterEventListener.onNodeAdded debug log shows the array was empty when the 2nd node (nifi1) is added:
ClusterEventListener.onNodeAdded. 2018-10-05 07:06:42,883 DEBUG [Process Cluster Protocol Request-10] o.a.n.c.q.c.SocketLoadBalancedFlowFileQueue Node Identifier nifi1.example.com:8080 added to cluster. Node ID's changing from [] to [nifi1.example.com:8080]
