Profiler for Lua in Hammerspoon

[asmagill]

It's extremely crude, and I'm not yet 100% convinced its accurate enough to actually be useful, but if anyone is interested, I've put together a really simplistic profiler for looking at Hammerspoon's executing lua code...

https://github.com/asmagill/hammerspoon-config-take2/blob/master/_scratch/profile.lua

It hooks into the debug library with debug.sethook and tracks calls and returns... Looking online this appears to be the most common approach, but most I saw were aimed at 5.1... one (that I found after starting this) also checks line-by-line, but again looks like it focuses on 5.1 and LuaJit, but does say LuaJit is optional, so it may work with a little tweaking... it's at https://github.com/geoffleyland/luatrace if anyone wants to take a crack at it.

At any rate, I put this up for review, ridicule, feedback, whatever...

And if anyone knows of a better tool, I'm all ears -- like I said, a quick (but definitely not thorough) googling showed mostly similar scripts or things aimed at earlier lua versions.

[randomeizer]

This requires your new coroutine support by the looks?

[asmagill]

No, but it will work with it. If you're running stock (or a dev build without the coroutine branch) then you can ignore the notes about coroutines... it will just wrap functions you aren't using anyways.

[asmagill]

Ok, if you downloaded the file earlier, trash it and get the latest version... the original mishandled tail calls completely. The comments also give some more details on using it.

I also changed the report format (I think this is easier to understand). By default, it doesn't include C functions in the report, though you can add those by passing true as an argument to the dump function.

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The other project I linked to looks like it produces a line-by-line trace with a time given for each line... this would be extremely slow as it would mean using the line debug hook and then saving/writing data for each and every line... right now, I'm more interested in identifying slow functions so I can look closer at them and see if there is a better way, so I don't care about an actual trace... if there is interest, I may see about adding that later, but its not my priority...

Or someone else can do it sooner (or see about porting their code... the main things I see that would have to be addressed is that lua 5.1 didn't report tail call but instead reported tail return... not sure how/if that would change the logic, and I'm not sure how they're getting the debug hook invoked on coroutine threads (maybe 5.1 just used one rather than a separate one per thread?)