I vote for ack=1. It is a reasonable tradeoff between performance and reliability.
On 03/05/2013 08:13 AM, Jun Rao wrote:
Chris, Joe, Yes, the default ack is currently 0. Let me explain the ack mode a bit more so that we are on the same page (details are covered in my ApachCon presentation http://www.slideshare.net/junrao/kafka-replication-apachecon2013) . There are only 3 ack modes that make sense. ack=0: producer waits until the message is in the producer's socket buffer ack=1: producer waits until the message is received by the leader ack=-1: producer waits until the message is committed The tradeoffs are: ack=0: lowest latency; some data loss during broker failure ack=1: lower latency; a few data loss during broker failure ack=-1: low latency; no data loss during broker failure All cases work with replication factor 1, which is the default setting out of box. With ack=1/-1, the producer may see some error when the leader hasn't been being elected. However, the number of errors should be small since typically leaders are elected very quickly. The argument for making the default ack 0 is that (1) this is the same behavior you get in 0.7 and (2) the producer runs fastest in this mode. The argument for making the default ack 1 or -1 is that they gave you better reliability. I am not sure what's the best thing to do that here since correct setting really depends on the application. What do people feel? Thanks, Jun
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