How can I find out where the runtime.futex is coming from? It only has "System" as its parent
works "go tool pprof" with cpu profile for https://github.com/vimeo/statsdaemon and typing "web". I am getting svg profile using runtime.futex extensively, but I can't figure out where it comes from, it just says "System". I want to know what code my program is calling that is causing so much time to spend on runtime.futex.
Of course, I passed in '-nodefraction = 0' which makes it not delete nodes in the web svg view, although it says "Showing 80 top nodes out of 246 (cum> = 0.11s)", it might be related.
I tried https://code.google.com/p/gperftools/ and it shows the same thing. Vis does not contain nodes or edges, but still runtime.futex only appears under System and that's the root node :?
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Futex or "Fast User Mutex Space" is a linux system call that is used for basic locking. I assume the runtime uses it quite a bit under the hood.
Not seeing some of the code, which is hard to say for sure, but for highly concurrent code with a lot of coordination using pipes, it is possible that the futex calls do indeed come from System and have no special functionality.
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