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https://issues.apache.org/jira/browse/KAFKA-7548?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mayuresh Gharat updated KAFKA-7548:
-----------------------------------
Description:
In KafkaConsumer, when we do a poll, we fetch data asynchronously from kafka
brokers that is buffered in completedFetch queue. Now if we pause a few
partitions, in next call to poll we remove the completedFetches for those
paused partitions. Normally, if an application is calling pause on
topicPartitions, it is likely to return to those topicPartitions in near future
and when it does, with the current design we would have to re-fetch that data.
At Linkedin, we made a hotfix to see if NOT throwing away the prefetched data
would improve the performance for stream applications like Samza. We ran a
benchmark were we compared what is the throughput w.r.t to different values of
maxPollRecords.
We had a consumer subscribed to 10 partitions of a high volume topic and paused
predefined number partitions for every poll call. The partitions to pause were
chosen randomly for each poll() call.
* Time to run Benchmark = 60 seconds.
* MaxPollRecords = 1
* Number of TopicPartition subscribed = 10
||Number Of Partitions Paused||Number of Records consumed (Before fix)||Number
of Records consumed (After fix)||
|9|2087|4884693|
was:
In KafkaConsumer, when we do a poll, we fetch data asynchronously from kafka
brokers that is buffered in completedFetch queue. Now if we pause a few
partitions, in next call to poll we remove the completedFetches for those
paused partitions. Normally, if an application is calling pause on
topicPartitions, it is likely to return to those topicPartitions in near future
and when it does, with the current design we would have to re-fetch that data.
At Linkedin, we made a hotfix to see if NOT throwing away the prefetched data
would improve the performance for stream applications like Samza. We ran a
benchmark were we compared what is the throughput w.r.t to different values of
maxPollRecords.
We had a consumer subscribed to 10 partitions of a high volume topic and paused
predefined number partitions for every poll call. The partitions to pause were
chosen randomly for each poll() call. We ran this benchmark multiple times
pausing different number for of partitions for each run. Here are the results :
* Time to run Benchmark = 60 seconds.
* MaxPollRecords = 1
* Number of TopicPartition subscribed = 10
*Before fix*
||Number Of Partitions Paused||Number of Records consumed||
|0|6424753|
|2|10495|
|4|5004|
|6|3152|
|8|2237|
|9|2087|
*After fix*
||Number Of Partitions Paused||Number of Records consumed||
|0|5846512|
|2|5269557|
|4|5213496|
|6|4519645|
|8|4383300|
|9|4884693|
> KafkaConsumer should not throw away already fetched data for paused
> partitions.
> -------------------------------------------------------------------------------
>
> Key: KAFKA-7548
> URL: https://issues.apache.org/jira/browse/KAFKA-7548
> Project: Kafka
> Issue Type: Improvement
> Components: clients
> Reporter: Mayuresh Gharat
> Assignee: Mayuresh Gharat
> Priority: Major
>
> In KafkaConsumer, when we do a poll, we fetch data asynchronously from kafka
> brokers that is buffered in completedFetch queue. Now if we pause a few
> partitions, in next call to poll we remove the completedFetches for those
> paused partitions. Normally, if an application is calling pause on
> topicPartitions, it is likely to return to those topicPartitions in near
> future and when it does, with the current design we would have to re-fetch
> that data.
> At Linkedin, we made a hotfix to see if NOT throwing away the prefetched data
> would improve the performance for stream applications like Samza. We ran a
> benchmark were we compared what is the throughput w.r.t to different values
> of maxPollRecords.
> We had a consumer subscribed to 10 partitions of a high volume topic and
> paused predefined number partitions for every poll call. The partitions to
> pause were chosen randomly for each poll() call.
> * Time to run Benchmark = 60 seconds.
> * MaxPollRecords = 1
> * Number of TopicPartition subscribed = 10
> ||Number Of Partitions Paused||Number of Records consumed (Before
> fix)||Number of Records consumed (After fix)||
> |9|2087|4884693|
>
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