[KAFKA-171] Kafka producer should do a single write to send message sets

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.7, 0.8.0
• Fix Version/s: 0.8.0
• Component/s: core
• Assignee: Jay Kreps
• Reporter: Jay Kreps
• Created: 26/Oct/11 17:52
• Updated: 23/Nov/11 07:30
• Resolved: 23/Nov/11 07:30

Description

From email thread:
http://mail-archives.apache.org/mod_mbox/incubator-kafka-dev/201110.mbox/[e-mail]%3e
> Before sending an actual message, kafka producer do send a (control) message of 4 bytes to the server. Kafka producer always does this action before send some message to the server.

I think this is because in BoundedByteBufferSend.scala we do essentially
channel.write(sizeBuffer)
channel.write(dataBuffer)

The correct solution is to use vector I/O and instead do
channel.write(Array(sizeBuffer, dataBuffer))