hi: recently we tried to upgrade our kafka cluster 0.10.0.1 to 2.3.0. we know kafka upgrade should: 1.use 2.3.0.jar and restart all brokers 2.unset inter.broker.protocol.version=0.10.0.1 and restart all brokers 3.unset log.message.format.version=0.10.0.1 and restart all brokers we have 15 clusters and most of them have already complete step 1,2. but there are 2 custers left will decrease message produce speed when all brokers unset inter.broker.protocol.version=0.10.0.1 and restart. this cluster has 5 brokers, we unset inter.broker.protocol.version=0.10.0.1 and restart all brokers, then it seems after several minutes , auto leader rebalance triggered, then some topics' producer decrease their produce speed. when this happened: 1.both client & brokers cpu usage down,memory usage not change 2.we found ioutil and io bandwidth is very slow ,so it almost impossible that io has any performance issue. 3.we found some consumer group that has large lag before will keep consume message without consume speed change,so it seems that consumer speed not be affected 4.we found not all topics' produce speed are down. the topic has higest message produce speed will decrease certainly and others are random. we have tried to upgrade many times,every time has different topics decrease produce speed. 5.we only fonud NOT_LEADER_FOR_PARTITION error in producers' log,but it should be ok when brokers restart. and there are no any error in brokers' log. 6. our producer will execute produce.flush() immediately after every producer.send() executed. i doubt whether its a big performace effect after we upgrade to 2.3.0? 7.we have open producers' trace log, we found brokers' response didn't has very large latency but send and request num reduce.
we hope some hint ,thx...