At some point, I hope to create a Notes section on my website that will turn Markdown files into a list of notes. This is basically how the blog works. But, I'm kind of busy. And since Gatsby seems like it's dead, I'm not sure that I want to invest a whole lot of time into it. (Although putting the notes in markdown seems like a good idea for compatibility.)

Anyway, here is my first very short note on Profiling.

SpeedScope

SpeedScope is an awesome tool for visualizing profiler output. It has a flame graph view that is wonderful. I also like to use the Sandwich view, sorting by total time and simply looking for the first function that I recognize. This is often the culprit.

The documentation is pretty good. It also shows how to record profiles in compatible formats for most platforms. I mostly use py-spy and perf.

Java

The one notably missing platform is Java! Luckily, it's not too hard to convert Java's async-profiler output to a format that SpeedScope can read. Here's how I do it:

• Download async-profiler
• Create an output file in collapsed format
• You can do this in several ways, such as:
• ./asprof start -i 1s Ghidra followed by ./asprof stop -o collapsed -f /tmp/out.prof.collapsed Ghidra
• ./asprof collect -d 60 -o collapsed -f /tmp/out.prof.collapsed Ghidra
• Then open out.prof.collapsed in SpeedScope.

The collapsed format takes a while to parse, so it might be worth it to export the native SpeedScope format.