[KAFKA-6441] FetchRequest populates buffer of size MinBytes, even if response is smaller

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Invalid
• Affects Version/s: 0.11.0.1
• Assignee: Unassigned
• Reporter: Ivan Babrou
• Created: 11/Jan/18 05:09
• Updated: 13/Jan/18 01:23
• Resolved: 13/Jan/18 01:23

Description

We're using Sarama Go client as consumer, but I don't think it's relevant. Producer is syslog-ng with Kafka output, I'm not quite sure which log format Kafka itself is using, but I can assume 0.11.0.0, because that's what is set in topic settings.

Our FetchRequest has minSize = 16MB, maxSize = 64, maxWait = 500ms. For a silly reason, Kafka decides to reply with at least minSize buffer with just one 1KB log message. When Sarama was using older consumer API, everything was okay. When we upgraded to 0.11.0.0 consumer API, consumer traffic for 125Mbit/s topic spiked to 55000Mbit/s on the wire and consumer wasn't even able to keep up.

1KB message in a 16MB buffer is 1,600,000% overhead.

I don't think there's any valid reason to do this.

It's also mildly annoying that there is no tag 0.11.0.1 in git, looking at changes is harder than it should be.