Hi, We have just made inspection on the message format and found some information unclear to us. Before the investigation, I did know that each Kafka message has an overhead of only 10 bytes.
Below is what we have done with Kafka 0.7 RC2 on a CentOS 5.6 server: - start kafka server on port 4444 - tcpdump -i lo -w test.pcap port 4444 and host localhost -vvvvv - start kafka producer - have kafka producer send some sort of message (hello, aaa) to the server We found 2 important items: 1. 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. 2. Sending a message of 15 bytes (10 bytes for overhead + 5 bytes for the message payload) from the producer to the server gives us an IP packet of 83 bytes (IP header: 20, TCP header: 32, Data: 31 bytes). The data of the IP packet is 31 instead of 15 bytes Could you please give us a detailed explanation about these 2 items? Please also see the attachment for further information. Thanks, ~Thai
