When to use Apache Kafka log roll jitter?

Question

There are two log roll jitter related parameters in config doc, i.e., log.roll.jitter.ms/log.roll.jitter.hours. Both of them are marked as high importance, but I have no idea when to use it.

What's the scenario to set log roll jitter?

Answer 1

Roll checks are performed on message appends. So if you want to roll out log segments every 10 hours, you might want to set an buffer interval (i.e jitter), let's say 1 hour before in which this rolling can take place in case a message is appended in that period.

More specifically, a time-trigged segment rollout will take place when:

timeWaitedForRoll > log.roll.ms - log.roll.jitter.ms

The log.roll.jitter.hours parameter is converted into the correspoinding milliseconds.