> > > Than how it achieve zookeeper-based load balance on per-request basis?
You are asking two related but different questions. One is how does load balancing work and the other is how does broker discovery works. Jun explained how load balancing works and how requests are routed to partitons. In 0.7, there were 2 options for broker discovery - zookeeper and hardware load balancer (VIP). The zookeeper based producer got notified by zookeeper whenever a new broker came up or an existing broker went down. In 0.8, we got rid of zookeeper from the producer and replaced it with a metadata API. On startup and whenever a request fails, the producer refreshes its view of the cluster by sending a metadata request to any of the brokers. So if a broker goes down or a new broker comes up, the leader for some partitions might change and the producer will know since its requests to the older leaders will fail. Hope that helps, Neha On Mon, Jan 14, 2013 at 9:52 PM, Jun Rao <jun...@gmail.com> wrote: > Basically, we spread partitions among multiple brokers. If a message is > sent without a key, the producer picks a random partition to balance the > load. If a message has a key, the default partitioner hashes the key to one > of the partitions deterministically. Then, the load may not always be > balanced. > > Thanks, > > Jun > > On Mon, Jan 14, 2013 at 9:35 PM, Jun Guo -X (jungu - CIIC at Cisco) < > ju...@cisco.com> wrote: > > > Hi, > > We know, in kafka 0.8, producer connect to broker directly, it without > > connecting to zookeeper. Than how it achieve zookeeper-based load balance > > on per-request basis? > > Actually, when a topic be created, its partition will distributed in one > > or more brokers. When a message be sent, it will be delivered to a > certain > > partition according to its key word. That is to say ,a certain must be > sent > > to a fixed partition on a fixed broker. How the so called load balancing > > works? > > > > Best Regards > > >
