A short time ago in a galaxy nearby, Domas Mituzas wrote about contention profiling with GDB stack traces. Mark Callaghan found the technique useful, and contributed an awk script (in the comments) to aggregate stack traces and identify which things are blocking most threads. I’ve used it myself a time or five. But I’ve found myself wanting it to be fancier, for various reasons. So I wrote a little utility that can aggregate and pretty-print backtraces. It can handle unresolved symbols, and aggregate by only the first N lines of the stack trace. Here’s an example of a mysqld instance that’s really, really frozen up:

bt-aggregate -4 samples/backtrace.txt | head -n12
2396 threads with the following stack trace:
        #0  0x00000035e7c0a4b6 in …

In the last six months, things have gotten much busier in the world of MySQL performance. That is, making MySQL and InnoDB scale faster out of the box. This is a great trend and I hope it keeps going. At this point I’m fighting to find enough time to read about what people are doing; I can’t keep up fast enough to actually understand the improvements. That’s also good.

The blogs that are posting the most news and analysis are MySQL Performance Blog, Mikael Ronstrom’s blog, DimitriK’s blog, and Mark Callaghan’s blog.