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https://issues.apache.org/jira/browse/KAFKA-3565?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15244946#comment-15244946
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Jiangjie Qin commented on KAFKA-3565:
-------------------------------------
[~ijuma] A few comments:
1. The performance improvement introduced in KIP31/32 is on the broker side.
KIP32 introduced 8 more bytes to the message, so it is expected the none
compressed throughput to be less in terms of the user bytes.
2. When we test throughput, it is important to know that which specific part we
consider as the bottleneck. In this benchmark, because we have 6 partitions it
is very likely the bottleneck would become the user thread of the producer. If
that is the case, for 100B message, KIP32 introduced another 8 bytes for
timestamp, so for each messages there are 8 more bytes to compress. Even if the
broker avoids re-compression, it is simply waiting for the producer to producer
more data so it has no impact on the throughput. If we want to see whether the
broker is doing better, we should check the latency and I think we will see the
difference.
3. Snappy is much faster than gzip in terms or compression and recompression,
so the elimination of re-compression might not have as prominent impact as gzip
on the broker side.
So in the above benchmark, I don't think it actually measures the throughput of
the broker, but only measures the the max throughput of one single user thread
in the producer, which is expected to be worse than before because we have an
extra 8 bytes overhead when the message size is 100B.
BTW, we should add the number of caller thread option to the
ProducerPerformance (currently I usually a tweaked version of
ProducerPerformance), I think we can do this in KAFKA-3554.
> Producer's throughput lower with compressed data after KIP-31/32
> ----------------------------------------------------------------
>
> Key: KAFKA-3565
> URL: https://issues.apache.org/jira/browse/KAFKA-3565
> Project: Kafka
> Issue Type: Bug
> Reporter: Ismael Juma
> Priority: Critical
> Fix For: 0.10.0.0
>
>
> Relative offsets were introduced by KIP-31 so that the broker does not have
> to recompress data (this was previously required after offsets were
> assigned). The implicit assumption is that reducing CPU usage required by
> recompression would mean that producer throughput for compressed data would
> increase.
> However, this doesn't seem to be the case:
> {code}
> Commit: eee95228fabe1643baa016a2d49fb0a9fe2c66bd (one before KIP-31/32)
> test_id:
> 2016-04-15--012.kafkatest.tests.benchmark_test.Benchmark.test_producer_throughput.topic=topic-replication-factor-three.security_protocol=PLAINTEXT.acks=1.message_size=100.compression_type=snappy
> status: PASS
> run time: 59.030 seconds
> {"records_per_sec": 519418.343653, "mb_per_sec": 49.54}
> {code}
> Full results: https://gist.github.com/ijuma/0afada4ff51ad6a5ac2125714d748292
> {code}
> Commit: fa594c811e4e329b6e7b897bce910c6772c46c0f (KIP-31/32)
> test_id:
> 2016-04-15--013.kafkatest.tests.benchmark_test.Benchmark.test_producer_throughput.topic=topic-replication-factor-three.security_protocol=PLAINTEXT.acks=1.message_size=100.compression_type=snappy
> status: PASS
> run time: 1 minute 0.243 seconds
> {"records_per_sec": 427308.818848, "mb_per_sec": 40.75}
> {code}
> Full results: https://gist.github.com/ijuma/e49430f0548c4de5691ad47696f5c87d
> The difference for the uncompressed case is smaller (and within what one
> would expect given the additional size overhead caused by the timestamp
> field):
> {code}
> Commit: eee95228fabe1643baa016a2d49fb0a9fe2c66bd (one before KIP-31/32)
> test_id:
> 2016-04-15--010.kafkatest.tests.benchmark_test.Benchmark.test_producer_throughput.topic=topic-replication-factor-three.security_protocol=PLAINTEXT.acks=1.message_size=100
> status: PASS
> run time: 1 minute 4.176 seconds
> {"records_per_sec": 321018.17747, "mb_per_sec": 30.61}
> {code}
> Full results: https://gist.github.com/ijuma/5fec369d686751a2d84debae8f324d4f
> {code}
> Commit: fa594c811e4e329b6e7b897bce910c6772c46c0f (KIP-31/32)
> test_id:
> 2016-04-15--014.kafkatest.tests.benchmark_test.Benchmark.test_producer_throughput.topic=topic-replication-factor-three.security_protocol=PLAINTEXT.acks=1.message_size=100
> status: PASS
> run time: 1 minute 5.079 seconds
> {"records_per_sec": 291777.608696, "mb_per_sec": 27.83}
> {code}
> Full results: https://gist.github.com/ijuma/1d35bd831ff9931448b0294bd9b787ed
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