Github user MikeThomsen commented on the issue:
https://github.com/apache/nifi/pull/2448
@mattyb149 I put it back to batch size and got rid of the configuration
option for progressive commits. The new behavior is the default and for
individual flowfiles it checks to see if the batch size was set and uses that
for when to do a commit, otherwise it uses the default of 100 flowfiles. I feel
like that's a good compromise for when batch size is not set.---
