I have been using the logstash-kafka-input plugin for a while now, on logstash version 2.1.0. We recently just upgraded out logstash instances from 2.1.0 to 5.1.2, and we have started seeing errors of this type rather freequently:
[2017-01-20T18:25:32,085][WARN ][org.apache.kafka.clients.consumer.internals.ConsumerCoordinator] Auto offset commit failed for group logstash: Commit cannot be completed since the group has already rebalanced and assigned the partitions to another member. This means that the time between subsequent calls to poll() was longer than the configured session.timeout.ms, which typically implies that the poll loop is spending too much time message processing. You can address this either by increasing the session timeout or by reducing the maximum size of batches returned in poll() with max.poll.records.
We've been able to fix this by increasing the configurations:
max_partition_fetch_bytes => "100000" session_timeout_ms => "90000" request_timeout_ms => "100000"
But why would this start happening in 5.0?