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https://issues.apache.org/jira/browse/KAFKA-9387?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17010835#comment-17010835
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ASF GitHub Bot commented on KAFKA-9387:
---------------------------------------
CodingFabian commented on pull request #7910: KAFKA-9387: Use non JNI LZ4
Hashing for header checksums,
URL: https://github.com/apache/kafka/pull/7910
since they are just a few bytes and the Java Version outperforms the native
version
see: https://lz4.github.io/lz4-java/1.3.0/xxhash-benchmark/
### Committer Checklist (excluded from commit message)
- [ ] Verify design and implementation
- [ ] Verify test coverage and CI build status
- [ ] Verify documentation (including upgrade notes)
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> LZ4 Compression creates significant unnecessary CPU usage
> ---------------------------------------------------------
>
> Key: KAFKA-9387
> URL: https://issues.apache.org/jira/browse/KAFKA-9387
> Project: Kafka
> Issue Type: Bug
> Components: clients
> Affects Versions: 2.4.0
> Reporter: Fabian Lange
> Priority: Major
> Attachments: Screenshot 2020-01-08 at 16.52.38.png
>
>
> KafkaLZ4BlockOutputStream and KafkaLZ4BlockInputStream perform checksumming
> on 3 bytes in the header. This is potentially quite unnecessary, but this
> ticket proposes a solution to improve the performance 10x.
> {{kafka-downstream-0 id=152 state=RUNNABLE
> at net.jpountz.xxhash.XXHashJNI.XXH32(Native Method)
> at net.jpountz.xxhash.XXHash32JNI.hash(XXHash32JNI.java:30)
> at
> org.apache.kafka.common.record.KafkaLZ4BlockOutputStream.writeHeader(KafkaLZ4BlockOutputStream.java:156)
> at
> org.apache.kafka.common.record.KafkaLZ4BlockOutputStream.<init>(KafkaLZ4BlockOutputStream.java:85)
> at
> org.apache.kafka.common.record.KafkaLZ4BlockOutputStream.<init>(KafkaLZ4BlockOutputStream.java:125)
> at
> org.apache.kafka.common.record.CompressionType$4.wrapForOutput(CompressionType.java:101)
> at
> org.apache.kafka.common.record.MemoryRecordsBuilder.<init>(MemoryRecordsBuilder.java:130)
> at
> org.apache.kafka.common.record.MemoryRecordsBuilder.<init>(MemoryRecordsBuilder.java:166)
> at
> org.apache.kafka.common.record.MemoryRecords.builder(MemoryRecords.java:534)
> at
> org.apache.kafka.common.record.MemoryRecords.builder(MemoryRecords.java:516)
> at
> org.apache.kafka.common.record.MemoryRecords.builder(MemoryRecords.java:464)
> at
> org.apache.kafka.clients.producer.internals.RecordAccumulator.recordsBuilder(RecordAccumulator.java:245)
> at
> org.apache.kafka.clients.producer.internals.RecordAccumulator.append(RecordAccumulator.java:222)
> at
> org.apache.kafka.clients.producer.KafkaProducer.doSend(KafkaProducer.java:917)
> at
> org.apache.kafka.clients.producer.KafkaProducer.send(KafkaProducer.java:856)
> at
> org.apache.kafka.clients.producer.KafkaProducer.send(KafkaProducer.java:743)}}
> by default Kafka doesn't do checksumming on blocks (blockChecksum=false)
> but it does doe checksumming on the header
> The header however is static, so its checksumming the same 6 or 2 bytes over
> and over again.
> Currently it uses the {{XXHashFactory.fastestInstance().hash32()}}
> but this will be a JNI one.
> For 2 bytes however, this is 10x slower than the java one, so we should
> replace it with {{fastestJavaInstance}}.
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