Hi , I am trying to understand the Kafka log flush behavior. My understanding is when the broker specifies broker config param "log.flush.interval.ms", it will specify log config param "flush.ms" internally. In logManager logic, when the log exceed flush.ms, it will call Log.flush which will call FileChannel.force(true) and MappedByteBuffer.flush() .
Couple of questions: 1. I am wondering if the fsync operation is called by the last two routines internally? 2. If log.flush.interval.ms is not specified, is it true that Kafka let OS to handle pagecache flush in background? 3. If we specify ack=1 and ack=-1 in new producer, do those request only persist in pagecache or actual disk? Thanks, -Tao
