Nifi problem access UI

[#1]

Hello,

We have configured Nifi via Ambari HDF. Its a 3 node cluster. It was working since last 2 weeks but suddenly now we are facing issues while accessing Web UI.

Currently i am getting below error while access the UI.

Cannot replicate request to Node ip-*******.eu-central-1.compute.internal:8080 because the node is not connected

At times, i am able to access the UI but than after few seconds it refresh and pops up with this error. I have tried starting and stopping all components but the problem still persists.

Anyone who has faced similar issue? What is the solution?

Thanks in advance.

Laeeq -

[#2]

@Laeeq Ahmad

NiFi uses zookeeper when clustered for election of both Cluster Coordinator and Primary node. Once a Cluster coordinator has been elected, all nodes in your cluster will start sending heartbeats to that node. If heartbeats are not received in a timely manor, the node may become disconnected. Should the heartbeat from a disconnected node come in later, the node will go through the process of connection to the cluster again.

There are a couple common reason that may cause issues with heartbeats.

1. Network issues (latency/packet loss) between NiFi nodes and/or zookeeper.

2. Excessive Java garbage collection (stop-the-world events) occurring on your NiFi node(s). During GC heartbeats will not be sent.

To see if it is just a small latency issue, try adjusting the following timeout settings in NiFi:

Try changing the "nifi.cluster.node.xxx" timeouts from 5 to 30 seconds. Try changing the "nifi.zookeeper.xxx" timeouts from 3 to 10 seconds.

These changes will require a NiFi restart to take affect.

Thanks,

Matt