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Posted to dev@kafka.apache.org by "Ismael Juma (JIRA)" <ji...@apache.org> on 2016/04/11 08:56:25 UTC
[jira] [Comment Edited] (KAFKA-3160) Kafka LZ4 framing code
miscalculates header checksum
[ https://issues.apache.org/jira/browse/KAFKA-3160?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15234578#comment-15234578 ]
Ismael Juma edited comment on KAFKA-3160 at 4/11/16 6:56 AM:
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[~guozhang], this proposal doesn't seem to affect when we lose zero-copy. That depends on the message format version and the client version. This proposal just changes the LZ4 format for message format 1. Do I understand correctly [~dana.powers]?
was (Author: ijuma):
[~guozhang], this proposal doesn't seem to affect when we lose zero-copy. That depends on the message format version and the client version. This proposal just changes the LZ4 format for message format 1. Right?
> Kafka LZ4 framing code miscalculates header checksum
> ----------------------------------------------------
>
> Key: KAFKA-3160
> URL: https://issues.apache.org/jira/browse/KAFKA-3160
> Project: Kafka
> Issue Type: Bug
> Components: compression
> Affects Versions: 0.8.2.0, 0.8.2.1, 0.9.0.0, 0.8.2.2, 0.9.0.1
> Reporter: Dana Powers
> Assignee: Magnus Edenhill
> Labels: compatibility, compression, lz4
>
> KAFKA-1493 partially implements the LZ4 framing specification, but it incorrectly calculates the header checksum. This causes KafkaLZ4BlockInputStream to raise an error [IOException(DESCRIPTOR_HASH_MISMATCH)] if a client sends *correctly* framed LZ4 data. It also causes KafkaLZ4BlockOutputStream to generate incorrectly framed LZ4 data, which means clients decoding LZ4 messages from kafka will always receive incorrectly framed data.
> Specifically, the current implementation includes the 4-byte MagicNumber in the checksum, which is incorrect.
> http://cyan4973.github.io/lz4/lz4_Frame_format.html
> Third-party clients that attempt to use off-the-shelf lz4 framing find that brokers reject messages as having a corrupt checksum. So currently non-java clients must 'fixup' lz4 packets to deal with the broken checksum.
> Magnus first identified this issue in librdkafka; kafka-python has the same problem.
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