[jira] [Created] (NIFI-6905) GetTwitter processor, configured to run on primary node only, initializes connection to Twitter API from every NiFi cluster node, even on non-primary nodes

["Kourge (Jira)" <ji...@apache.org>]

Kourge created NIFI-6905:
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             Summary: GetTwitter processor, configured to run on primary node only, initializes connection to Twitter API from every NiFi cluster node, even on non-primary nodes
                 Key: NIFI-6905
                 URL: https://issues.apache.org/jira/browse/NIFI-6905
             Project: Apache NiFi
          Issue Type: Bug
          Components: Extensions
    Affects Versions: 1.0.0
            Reporter: Kourge


I have a *GetTwitter* processor running on a 3-nodes NiFi cluster and configured to be executed on the primary node only.
The symptom is that there is a too high frequency of HTTP 420 ("Enhance Your Calm") exceptions on GetTwitter processor start.

I made the following tests:
 * With only 1 NiFi node. I was able to start/stop GetTwitter processor 10 times in a raw without any errors.
 * With 2 NiFi nodes running, HTTP 420 errors occurred after a few start/stop (sometimes even after a single start).

After an analysis of the source code and knowing https://issues.apache.org/jira/browse/NIFI-2592 I came to the conclusion that the GetTwitter processor is initializing the connection to Twitter API on each node of the cluster, even to non-primary nodes.

The `*onScheduled()*` method is run on every node (see: NIFI-2592) making connections to Twitter with `*client.connect()*`. Then the `*onTrigger()*` method consumes the tweets normally from the primary node.
Issue is that having more that one node initializing connections make Twitter API raise HTTP 420 errors.
{code:java}
ERROR
org.apache.nifi.processors.twitter.GetTwitter
GetTwitter[id=XYZ] Received error HTTP_ERROR: HTTP/1.1 420 Enhance Your Calm. Will attempt to reconnect
{code}
+*Proposed solutions:*+
 # Change the behavior of `*onScheduled()*` method to run only on primary node (as proposed in NIFI-2592)
 # Update GetTwitter processor implementation to not call `*client.connect()*` anymore from the `*onScheduled()*` method but only when *PrimaryNodeState* changes to *ELECTED_PRIMARY_NODE* (And when *PrimaryNodeState* changes to *PRIMARY_NODE_REVOKED*: perform a `*client.stop()*`)



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