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I saw a youtube talk on this one ... I think it was this one: https://www.youtube.com/watch?v=O1YP8QP9gLA

Really great stuff. The spot where he gets to a pretty good description of how he uses his flame graph is roughly here: https://youtu.be/O1YP8QP9gLA?t=611

With respect to that blog-post the bit about the truncated towers is a bit of a red herring if you're 100% new to flame graphs.

The real meaty bits are the wide sections.

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Generally you're right that the wide sections are where you want to focus your attention when looking for optimizations. The point I was trying to make in the blog post is that we had to take the flame graph visualization a step further to eliminate the noise obscuring a major hot spot. The large number of broken stacks was one of the first hurdles we had to cross to improve the clarity of the visualization.

BTW, this is a different flame graph and optimization than the one discussed in the YouTube video. We use flame graphs extensively throughout Netflix.

Can you write up how you fixed the broken call stacks? I've used Brendan's tools (with java-perf-map, also an awesome tool) to generate flame graphs for Scala code and had no idea I could only see 127 frames.

We ultimately should be fixing this with BPF, which we'll certainly post instructions for.

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