Hi Chris, Thank you for the clarification. Now I see what you mean. If your topology works correctly, I would not file it as a bug but as a possible improvement.
Best, Bruno On Wed, Oct 30, 2019 at 1:20 AM Chris Toomey <ctoo...@gmail.com> wrote: > > Bruno, > > I'm using a fork based off the 2.4 branch .It's not the global consumer but > the stream thread consumer that has the group id since it's built with the > main consumer config: > https://github.com/apache/kafka/blob/065411aa2273fd393e02f0af46f015edfc9f9b55/streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java#L1051 > . > > It shouldn't be creating a regular consumer for the topic since my topology > only has a single element, the GlobalKTable, which is populated by the > global consumer. My scala code: > > val builder: StreamsBuilder = new StreamsBuilder() > val gTable = builder.globalTable[K, V](...) > val stream = new KafkaStreams(builder.build(), props) > stream.start() > > > I can disable the stream thread consumer by configuring num.stream.threads > = 0, but why does it create this stream thread consumer in the first place > if it's not been requested in the topology? > > thx, > Chris > > On Tue, Oct 29, 2019 at 2:08 PM Bruno Cadonna <br...@confluent.io> wrote: > > > Hi Chris, > > > > What version of Streams are you referring to? > > > > On the current trunk the group.id property is removed from the config > > for the global consumer that populates the GlobalKTable. > > > > See the following code line > > > > https://github.com/apache/kafka/blob/065411aa2273fd393e02f0af46f015edfc9f9b55/streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java#L1149 > > > > Best, > > Bruno > > > > On Tue, Oct 29, 2019 at 8:12 PM Chris Toomey <ctoo...@gmail.com> wrote: > > > > > > We have some simple Kafka streams apps that populate GlobalKTables to use > > > as caches for topic contents. When running them with info-level logging > > > enabled, I noticed unexpected activity around group coordination > > (joining, > > > rebalancing, leaving, rejoining) that I didn't expect given that they > > need > > > to consume from all topic partitions vs. use the group load balancing > > > feature. > > > > > > I tracked this down to the way the consumer config. is generated for > > > a GlobalKTable consumer -- the groupId is set to the Kafka streams > > > application id instead of to null -- the consumer needlessly creates a > > > ConsumerCoordinator and thus intiiates all the needless associated > > > messaging and overhead. > > > > > > I was going to file a bug for this but per the contributing page am > > > bringing this up here first. Is there a reason why GlobalKTable consumers > > > should bear this group coordination overhead or should I go ahead and > > file > > > a ticket to remove it? > > > > > > thanks, > > > Chris > >
