Olson,Andrew created KAFKA-2189:
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Summary: Snappy compression of message batches less efficient in
0.8.2.1
Key: KAFKA-2189
URL: https://issues.apache.org/jira/browse/KAFKA-2189
Project: Kafka
Issue Type: Bug
Components: log
Affects Versions: 0.8.2.1
Reporter: Olson,Andrew
Assignee: Jay Kreps
We are using snappy compression and noticed a fairly substantial increase
(about 2.25x) in log filesystem space consumption after upgrading a Kafka
cluster from 0.8.1.1 to 0.8.2.1. We found that this is caused by messages being
seemingly recompressed individually (or possibly with a much smaller buffer or
dictionary?) instead of as a batch as sent by producers. We eventually tracked
down the change in compression ratio/scope to this [1] commit that updated the
snappy version from 1.0.5 to 1.1.1.3. The Kafka client version does not appear
to be relevant as we can reproduce this with both the 0.8.1.1 and 0.8.2.1
Producer.
Here are the log files from our troubleshooting that contain the same set of
1000 messages, for batch sizes of 1, 10, 100, and 1000. f9d9b was the last
commit with 0.8.1.1-like behavior prior to f5ab8 introducing the issue.
{noformat}
-rw-rw-r-- 1 kafka kafka 404967 May 12 11:45
/var/kafka2/f9d9b-batch-1-0/00000000000000000000.log
-rw-rw-r-- 1 kafka kafka 119951 May 12 11:45
/var/kafka2/f9d9b-batch-10-0/00000000000000000000.log
-rw-rw-r-- 1 kafka kafka 89645 May 12 11:45
/var/kafka2/f9d9b-batch-100-0/00000000000000000000.log
-rw-rw-r-- 1 kafka kafka 88279 May 12 11:45
/var/kafka2/f9d9b-batch-1000-0/00000000000000000000.log
-rw-rw-r-- 1 kafka kafka 402837 May 12 11:41
/var/kafka2/f5ab8-batch-1-0/00000000000000000000.log
-rw-rw-r-- 1 kafka kafka 382437 May 12 11:41
/var/kafka2/f5ab8-batch-10-0/00000000000000000000.log
-rw-rw-r-- 1 kafka kafka 364791 May 12 11:41
/var/kafka2/f5ab8-batch-100-0/00000000000000000000.log
-rw-rw-r-- 1 kafka kafka 380693 May 12 11:41
/var/kafka2/f5ab8-batch-1000-0/00000000000000000000.log
{noformat}
[1]
https://github.com/apache/kafka/commit/f5ab8e1780cf80f267906e3259ad4f9278c32d28
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