> On July 15, 2014, 5:51 p.m., Guozhang Wang wrote: > > core/src/main/scala/kafka/server/ReplicaManager.scala, line 484 > > <https://reviews.apache.org/r/23474/diff/1/?file=631878#file631878line484> > > > > I am wondering if this function will introduce more lock contention on > > leaderIsrUpdateLock? Every leaderReplicaIfLocal call will need to hold on > > its read lock while other requests at the same time may try to modify the > > leader option? > > Sriharsha Chintalapani wrote: > It might increase lock contention but writes to change the leadership > occurs not so frequently so using readLock wouldn't be much of an issue I > think. I also considered comparing ReplicaManager.localBrokerId with > Partition.leaderReplicaIdOpt without a lock this will present an issue where > the leader is changed and we might be comparing against old leader value. > Instead of using leaderReplicaIfLocal I can create another method > "checkLeader" in Partition which will return a boolean after obtaining a > readLock on leaderIsrUpdateLock. Right now there is unnecessary call going to > getReplica. > > Guozhang Wang wrote: > I think one optimization we can try at least is to grab the read lock > before the iteration to avoid grab/release on each partition during the > iteration.
The intention of maintaining a separate leaderPartitions is to make LeaderCount check an O(1) operation, instead of O(n). However, UnderReplicatedPartitions is still an O(n) operation and it's already paying the readLock overhead. So, making LeaderCount an O(n) operation with the readLock overhead probably won't be too bad. - Jun ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/23474/#review47785 ----------------------------------------------------------- On July 15, 2014, 1:18 a.m., Sriharsha Chintalapani wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/23474/ > ----------------------------------------------------------- > > (Updated July 15, 2014, 1:18 a.m.) > > > Review request for kafka. > > > Bugs: KAFKA-1483 > https://issues.apache.org/jira/browse/KAFKA-1483 > > > Repository: kafka > > > Description > ------- > > KAFKA-1483. Split Brain about Leader Partitions. > > > Diffs > ----- > > core/src/main/scala/kafka/server/ReplicaManager.scala > 6a56a772c134dbf1e70c1bfe067223009bfdbac8 > > Diff: https://reviews.apache.org/r/23474/diff/ > > > Testing > ------- > > > Thanks, > > Sriharsha Chintalapani > >
