MacOS Sierra massive slowdown in Java networking

I upgraded to MacOS Sierra, and have really been enjoying the shared clipboard. I haven’t really noticed any other new features that impact my day to day development, however I would advise Java developers to avoid it for the near future. I have searched and searched and I wasn’t coming up with any results. Then I found this blog post. This is definitely part of the problem. I made the host file changes and got a slight boost, but not enough to explain the whole thing.

First our original application is a monolithic Spring 4.2 app running in Tomcat. On my MacBook Pro it was taking 21-25 seconds to launch. After going to Sierra it started taking 75 seconds. Once I did the host file fix in the blog post above it started launching in 59 seconds. Still much worse than before.

Another Spring Boot micro service we have that does a lot of external api calls and also communicates through Amazon SQS would previously launch in 11 seconds on my laptop and now takes 141 seconds (150 prior to the fix outlined above). Even worse the messages to and from SQS and the third party API’s are painfully slow, sometimes taking 30 seconds or more to go through when previously they were almost instantaneous.

I am still searching for a fix for the issue, but it is practically unusable. I am debating if I am going to roll back to El Capitan, but at this point I would recommend people hold off on upgrading until there is a good understanding of what the slowdown is and how to fix it. Java itself when not hitting the network seems as fast as ever.