How hard would it be to fix this issue, where we have a topic filter that matches multiple topics, for the load to be distributed over multiple threads, and over multiple consumers? For some reason, I had thought this issue was fixed in 0.8, but I guess not?
I am currently using a single partition, for multiple topics. I worry that it won't scale ultimately to only ever have one thread on one consumer doing all the work......We could move to multiple partitions, but for ordering reasons in some use cases, this is not always ideal. Perhaps I can come up with some sort of dynamic topic sniffer, and have it evenly divide the available topics between the available consumers (and threads per consumer)! Is there a simple api within the kafka client code, for getting the list of topics? Jason On Fri, Aug 30, 2013 at 11:41 PM, Jun Rao <[email protected]> wrote: > It seems to me option 1) is easer. Option 2) has the same issue as option > 1) since you have to manage different while lists. > > A more general solution is probably to change the consumer distribution > model to divide partitions across topics. That way, one can create as many > streams as total # partitions for all topics. We can look into that in the > future. > > Thanks, > > Jun > > > On Fri, Aug 30, 2013 at 8:24 AM, Rajasekar Elango <[email protected] > >wrote: > > > Yeah. The actual bottleneck is actually number of topics that match the > > topic filter. Num of streams is going be shared between all topics it's > > consuming from. I thought about following ideas to work around this. (I > am > > basically referring to mirrormaker consumer in examples). > > > > Option 1). Instead of running one mirrormaker process with topic filter > > ".+", We can start multiple mirrormaker process with topic filter > matching > > each topic (Eg: mirrormaker1 => whitelist topic1.* , mirrormaker2 > > => whitelist topic2.* etc) > > > > But this adds some operations overhead to start and manage multiple > > processes on the host. > > > > Option 2) Modify mirrormaker code to support list of whitelist filters > and > > it should create message streams for each filter > > (call createMessageStreamsByFilter for each filter). > > > > What would be your recommendation..? If adding feature to mirrormaker is > > worth kafka, we can do option 2. > > > > Thanks, > > Raja. > > > > > > > > > > On Fri, Aug 30, 2013 at 10:34 AM, Jun Rao <[email protected]> wrote: > > > > > Right, but if you set #partitions in each topic to 16, you can use a > > total > > > of 16 streams. > > > > > > Thanks, > > > > > > Jun > > > > > > > > > On Thu, Aug 29, 2013 at 9:08 PM, Rajasekar Elango < > > [email protected] > > > >wrote: > > > > > > > With option 1) I can't really use 8 streams in each consumer, If I do > > > only > > > > one consumer seem to be doing all work. So I had to actually use > total > > 8 > > > > streams with 4 for each consumer. > > > > > > > > > > > > > > > > On Fri, Aug 30, 2013 at 12:01 AM, Jun Rao <[email protected]> wrote: > > > > > > > > > The drawback of 2), as you said is no auto failover. I was > suggesting > > > > that > > > > > you use 16 partitions. Then you can use option 1) with 8 streams in > > > each > > > > > consumer. > > > > > > > > > > Thanks, > > > > > > > > > > Jun > > > > > > > > > > > > > > > On Thu, Aug 29, 2013 at 8:51 PM, Rajasekar Elango < > > > > [email protected] > > > > > >wrote: > > > > > > > > > > > Hi Jun, > > > > > > > > > > > > If you read my previous posts, based on current re balancing > logic, > > > if > > > > we > > > > > > consumer from topic filter, consumer actively use all streams. > Can > > > you > > > > > > provide your recommendation of option 1 vs option 2 in my > previous > > > > post? > > > > > > > > > > > > Thanks, > > > > > > Raja. > > > > > > > > > > > > > > > > > > On Thu, Aug 29, 2013 at 11:42 PM, Jun Rao <[email protected]> > > wrote: > > > > > > > > > > > > > You can always use more partitions to get more parallelism in > the > > > > > > > consumers. > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > Jun > > > > > > > > > > > > > > > > > > > > > On Thu, Aug 29, 2013 at 12:44 PM, Rajasekar Elango > > > > > > > <[email protected]>wrote: > > > > > > > > > > > > > > > So what is best way to load balance multiple consumers > > consuming > > > > from > > > > > > > topic > > > > > > > > filter. > > > > > > > > > > > > > > > > Let's say we have 4 topics with 8 partitions and 2 consumers. > > > > > > > > > > > > > > > > Option 1) To load balance consumers, we can set num.streams=4 > > so > > > > that > > > > > > > both > > > > > > > > consumers split 8 partitions. but can only use half of > consumer > > > > > > streams. > > > > > > > > > > > > > > > > Option 2) Configure mutually exclusive topic filter regex > such > > > > that 2 > > > > > > > > topics will match consumer1 and 2 topics will match > consumer2. > > > Now > > > > we > > > > > > can > > > > > > > > set num.streams=8 and fully utilize consumer streams. I > believe > > > > this > > > > > > will > > > > > > > > improve performance, but if consumer dies, we will not get > any > > > data > > > > > > from > > > > > > > > the topic used by that consumer. > > > > > > > > > > > > > > > > What would be your recommendation? > > > > > > > > > > > > > > > > Thanks, > > > > > > > > Raja. > > > > > > > > > > > > > > > > > > > > > > > > On Thu, Aug 29, 2013 at 12:42 PM, Neha Narkhede < > > > > > > [email protected] > > > > > > > > >wrote: > > > > > > > > > > > > > > > > > >> 2) When I started mirrormaker with num.streams=16, looks > > > like > > > > 16 > > > > > > > > > consumer > > > > > > > > > threads were created, but only 8 are showing up as active > as > > > > owner > > > > > in > > > > > > > > > consumer offset tracker and all topics/partitions are > > > distributed > > > > > > > > between 8 > > > > > > > > > consumer threads. > > > > > > > > > > > > > > > > > > This is because currently the consumer rebalancing process > of > > > > > > assigning > > > > > > > > > partitions to consumer streams is at a per topic level. > > Unless > > > > you > > > > > > have > > > > > > > > at > > > > > > > > > least one topic with 16 partitions, the remaining 8 threads > > > will > > > > > not > > > > > > do > > > > > > > > any > > > > > > > > > work. This is not ideal and we want to look into a better > > > > > rebalancing > > > > > > > > > algorithm. Though it is a big change and we prefer doing it > > as > > > > part > > > > > > of > > > > > > > > the > > > > > > > > > consumer client rewrite. > > > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > Neha > > > > > > > > > > > > > > > > > > > > > > > > > > > On Thu, Aug 29, 2013 at 8:03 AM, Rajasekar Elango < > > > > > > > > [email protected] > > > > > > > > > >wrote: > > > > > > > > > > > > > > > > > > > So my understanding is num of active streams that a > > consumer > > > > can > > > > > > > > utilize > > > > > > > > > is > > > > > > > > > > number of partitions in topic. This is fine if we > consumer > > > from > > > > > > > > specific > > > > > > > > > > topic. But if we consumer from TopicFilter, I thought > > > consumer > > > > > > should > > > > > > > > > able > > > > > > > > > > to utilize (number of topics that match filter * number > of > > > > > > partitions > > > > > > > > in > > > > > > > > > > topic) . But looks like number of streams that consumer > can > > > use > > > > > is > > > > > > > > > limited > > > > > > > > > > by just number if partitions in topic although it's > > consuming > > > > > from > > > > > > > > > multiple > > > > > > > > > > topic. > > > > > > > > > > > > > > > > > > > > Here what I observed with 1 mirrormaker consuming from > > > > whitelist > > > > > > > '.+'. > > > > > > > > > > > > > > > > > > > > The white list matches 5 topics and each topic has 8 > > > > partitions. > > > > > I > > > > > > > used > > > > > > > > > > consumer offset checker to look at owner of each/topic > > > > partition. > > > > > > > > > > > > > > > > > > > > 1) When I started mirrormaker with num.streams=8, all > > > > > > > topics/partitions > > > > > > > > > are > > > > > > > > > > distributed between 8 consumer threads. > > > > > > > > > > > > > > > > > > > > 2) When I started mirrormaker with num.streams=16, looks > > like > > > > 16 > > > > > > > > consumer > > > > > > > > > > threads were created, but only 8 are showing up as active > > as > > > > > owner > > > > > > in > > > > > > > > > > consumer offset tracker and all topics/partitions are > > > > distributed > > > > > > > > > between 8 > > > > > > > > > > consumer threads. > > > > > > > > > > > > > > > > > > > > So this could be bottleneck for consumers as although we > > > > > > partitioned > > > > > > > > > topic, > > > > > > > > > > if we are consuming from topic filter it can't utilize > much > > > of > > > > > > > > > parallelism > > > > > > > > > > with num of streams. Am i missing something, is there a > way > > > to > > > > > make > > > > > > > > > > cosumers/mirrormakers to utilize more number of active > > > streams? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > Thanks, > > > > > > > > > > Raja. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > Thanks, > > > > > > > > Raja. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > Thanks, > > > > > > Raja. > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > Thanks, > > > > Raja. > > > > > > > > > > > > > > > -- > > Thanks, > > Raja. > > >
