IPv6

Last year I blogged about handling ipv6 lookups that caused threads to wait thus slowing them down. Not surprisingly I've come across this a few times since then. What is interesting is the effect it can have on throughput and response time. Testing showed that once -Djava.net.preferIPv4Stack=true was enabled the test had 8% improvements in both throughput and response time. This is truly interesting data. That is a big difference and a good reason to periodically take thread dumps even if everything seems to be running nominally. One never knows when they may uncover a gem of a performance boost like this one.