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ymattw / ydiff

View colored, incremental diff in workspace or from stdin, side by side and auto paged.
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perf: make ~2x faster by killing the hot loop #100

Closed joshuarli closed 4 years ago

joshuarli commented 4 years ago

Hi @ymattw, thanks for writing ydiff, I find it to be very useful and I see you've become active again.

I have a rather substantially modified fork of it, and managed to identify and optimize a very hot loop. This is an adaptation of https://github.com/joshuarli/ydiff/commit/e6c4a3e5f87923a791b3da52c57af8468f123b99.

In practice I've found roughly a 2x speedup: https://github.com/joshuarli/ydiff#Performance

Granted, the speedup is only really noticeable if you're rendering extremely large diffs.

ymattw commented 4 years ago

Thank you. I will take a closer look as soon as possible. The function was from another contributor, I am also worried about the readability. Of course performance enhancement is very good, would you mind share with me how did you measure the performance?

joshuarli commented 4 years ago

Thank you. I will take a closer look as soon as possible. The function was from another contributor, I am also worried about the readability. Of course performance enhancement is very good, would you mind share with me how did you measure the performance?

https://github.com/joshuarli/ydiff#Performance

I just used git log --patch on a large repo to generate a massive unified diff (500+ MB) and ran a profiler to inspect hot loops. I don't have those screenshots anymore, unfortunately, but I used the heatmap generated by https://github.com/nvdv/vprof.

ymattw commented 4 years ago

Thank you. I have some small nitpicks but I will clean myself later, together with some other simplification I planned.