I was calculating a long fractal zoom movie with Fractal eXtreme when I noticed that one of the phases seemed to be taking too long on my four-core eight-thread processor. A bit of investigation showed that this phase was effectively being done in a serial manner. All eight threads were calculating the same points, and overwriting each others results.

Amdahl’s law teaches us that the more you parallelize code the more the serial portions dominate, and this unnecessary serialization was making this particular zoom movie take more than 25% longer to calculate! This was going to add about two days of calculation time to the movie.

I fixed the bug and restarted the zoom movie calculation. The fixed version will be released soon, along with some other tweaks. More details later.

Give the Fractal eXtreme demo version a try – even with this bug it makes great use of all of your cores to explore fractals with the spin of a mouse wheel.

About brucedawson

I'm a retired programmer, ex-Google/Valve/Microsoft/etc., who was focused on optimization and reliability. Nothing's more fun than making code run 10x as fast. Unless it's eliminating large numbers of bugs. I also unicycle. And play (ice) hockey. And sled hockey. And juggle. And worry about whether this blog should have been called randomutf-8. 2010s in review tells more: https://twitter.com/BruceDawson0xB/status/1212101533015298048

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