A DIY Ruby Profiler!
A simple profiler can be nice to help detect how often different parts of our code are being run by using some statistical analysis and a few threading tricks. New Relic developer Jason Clark talks about how it’s more efficient to take samples than to use ruby profiler to profile every call and then walks us through building your own profiler.
This was a very insightful talk on how to analyze the backtrace of currently active threads. You can find the code for his DIY profiler on github.