@MaarufB You must have a lot of logging enabled that you expect multiple 10MB app.log files per minute. Was NiFi ever rolling files? Check your NiFi app.log for any Out of Memory (OOM) exceptions. Does not matter what class is throwing the OOM(s), once the NiFi process is having memory issues, it impacts everything within that service. If this is the case, you'll need to make changes to your dataflow(s) or increase the NiFi heap memory.
Secondly, check to make sure you have sufficient file handles for your NiFi process user. For example; - If your NiFi service is owned by the "nifi" user, make sure the open file limit is set to a very large value for this user (999999). A restart of the NiFi service before the change to file handles will be applied.
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