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From "Matthias J. Sax" <matth...@confluent.io>
Subject Re: Kafka Streams Session store performance degradation from to
Date Thu, 08 Nov 2018 00:13:39 GMT
Thanks for verifying.

>> From our perspective, it appears something happened after that made the
LRU Cache much slower for our use case. 

That is what I try to figure out. I went over the to
Jiras but found nothing I could point out. There are couple of
SessionStore related tickets, but none of them should have an effect
like this.

To narrow it down, it would be helpful to test with other versions, too.
Maybe and to see when the issue was introduced.

Can you also profile v0.10.2.1 so we can compare?

> What would you recommend for our next steps? 

Not sure. If you could help us to track down the issue, that would be
most helpful so get a fix (and you could run from a SNAPSHOT version to
get the fix -- not sure if this would be an option for you).


On 11/7/18 3:47 PM, jonathangordon@newrelic.com wrote:
> Hi Matthias,
> I upgraded to 2.0.0 and we're experiencing the same problem. I've posted a new screengrab
of a thread profile:
> https://imgur.com/a/2wncPHw
> From our perspective, it appears something happened after that made the LRU
Cache much slower for our use case. What would you recommend for our next steps? 
> Jonathan
> On 2018/11/06 19:22:16, "Matthias J. Sax" <matthias@confluent.io> wrote: 
>> Not sure atm why you see a performance degradation. Would need to dig
>> into the details.
>> However, did you consider to upgrade to 2.0 instead or 0.11?
>> Also note that we added a new operator `suppress()` in upcoming 2.1
>> release, that allows you to do rate control without caching:
>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-328%3A+Ability+to+suppress+updates+for+KTables
>> Hope this helps.
>> -Matthias
>> On 11/6/18 9:49 AM, Jonathan Gordon wrote:
>>> I have a Kafka Streams app that I'm trying to upgrade from to
>>> but when I do I notice that CPU goes way up and consumption goes
>>> down. A thread profile indicates that the most expensive task is during our
>>> aggregation, fetching from the cache.
>>> Thread profile with caching:
>>> https://imgur.com/l5VEsC2
>>> If I disable the cache both performance and consumption are good but we are
>>> producing every single aggregation modification, which is not what we want.
>>> Thread profile without caching:
>>> https://imgur.com/a/JK3nkou
>>> I read this thread, which seems relevant e
>>> https://lists.apache.org/thread.html/2b44e74eaec7172b107bcff96861cf8b4837f55a44714f69d033cc2e@%3Cusers.kafka.apache.org%3E
>>> Notably: "Note, that caching was _not_ introduced to reduce the writes to
>>> RocksDB, but to reduce the write the the changelog topic and to reduce the
>>> number of records send downstream."
>>> So how can we reduce the number of records sent downstream while
>>> maintaining the same performance characteristics that we have with caching
>>> turned off? Or put another way, how can I upgrade my app without taking a
>>> hit in performance or behavior?
>>> Thanks!

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