Nifi: Flowfile stuck in front of a processor group when flowfile concurrency is set to single batch per node
Hi Cloudera
Background: We run nifi as a standalone instance in a docker container in on all our stages, the statemanagement provider used by our instance is the local WAL backed provider.
Description: We observed that the flowfiles in front of one of our processor groups stopped to be ingested once in a while and it happens on all our stages without noticeable pattern. The flowfile concurrency policy of the processor group that stopped ingesting data is set to SINGLE_BATCH_PER_NODE and the outbound policy is set to BATCH_OUTPUT. The ingestion should continue since the processor group had already send out every flowfile in it, but it stopped.
There is only one brutal solution from our side(We need to delete the processor group and restore it from nifi registry again) and the occurrence of this issue had impacted our data ingestion.
As you can see in the screenshot that the processor group 'Delete before Insert' has no more flowfile to output but still it does not ingest the data queued in the input port
In the log file I found the following:
2024-06-03 11:34:01,772 TRACE [Timer-Driven Process Thread-15] o.apache.nifi.groups.StandardDataValve Will not allow data to flow into StandardProcessGroup[identifier=5eb0ad69-e8ed-3ba0-52da-af94fb9836cd,name=Delete before Insert] because Outbound Policy is Batch Output and valve is already open to allow data to flow out of group
Also in the diagnostics, I found the following for the 'Delete before Insert' processor group:
Process Group e6510a87-aa78-3268-1b11-3c310f0ad144, Name = Search and Delete existing reports(This is the parent processor group of the Delete before Insert)
Currently Have Data Flowing In: []
Currently Have Data Flowing Out: [StandardProcessGroup[identifier=5eb0ad69-e8ed-3ba0-52da-af94fb9836cd,name=Delete before Insert]]
Reason for Not allowing data to flow in:
Data Valve is already allowing data to flow out of group:
StandardProcessGroup[identifier=5eb0ad69-e8ed-3ba0-52da-af94fb9836cd,name=Delete before Insert]
Reason for Not allowing data to flow out:
Output is Allowed:
StandardProcessGroup[identifier=5eb0ad69-e8ed-3ba0-52da-af94fb9836cd,name=Delete before Insert]
Which is clearly not correct. since there are currently not data flowing out from the 'Delete before Insert' processor group
If you have any insight regarding this issue, it would be great if you car share it with me, also I think this could possibly be a nifi internal bug so I also opened an issue in nifi's jira page Here
Thank you for your time!
