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https://issues.apache.org/jira/browse/KAFKA-3565?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15252069#comment-15252069
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Jay Kreps commented on KAFKA-3565:
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[~ijuma] Yeah your data eliminates my guess. If the problem were the change in
batching you wouldn't see impact in the non-compressed case.
[~becket_qin] I don't think we have access to that google doc, but I'm not sure
how intuitive that is to me, maybe you can explain it more? For one thing the
timestamps themselves should be ultra compressible, how much bigger is the
resulting log with timestamps? Also, can we look at actual hprof output for one
case where there is a degradation and see which methods the change comes from
and confirm it is consistent with that theory?
One thing we noted in the last release was that System.currentTimeMillis() is
pretty expensive if it is in the critical path of send(). I wonder if the
difference remains if we manually set the timestamp to some fixed value and
don't do it dynamically with the system call?
> 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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