Deep Dives

I've added a lot of logging to my copy of Aeron to help me understand certain features. Every Cluster and Archive message is logged, as well as a few other key points like Election state changes. Each log line also has a stacktrace, so I can see where it was called from. This is incredibly verbose, so I wrote a post-processor to tidy it all up and produce a markdown file.

I created this purely for my own use while developing this website. I can run a scenario, then look back at the logs to see what cluster messages were sent, etc. I'll probably make it available, but it needs some tidying first.

Follower offline scenario

In the mean time, I've provided one of the scenarios on the next page. The whole page is generated, apart from the image, which I inserted manually. It still contains a lot of other random log messages for the last thing I was looking at (needs tidying).

One neat feature is that every single log line can be clicked to expand it. The expanded view shows message contents and a stack trace of where it was called from. I've provided this for info. I've found it a useful reference point that I keep going back to, to check something new.

This scenario starts a 3 node cluster, kills one of the followers, and doesn't restart it until a few leadership terms later. When it starts, it replicates 2 or 3 leadership terms, then uses catchup on the latest leadership term.