I'm porting a physics engine (chipmunk!) from C to javascript. Internally, chipmunk uses 2d vectors pretty extensively. In C, they're a simple struct passed by value. In javascript, my vectors are being allocated on the heap.
I did some benchmarks - in 5 seconds, chipmunk-js allocates about 20 million vectors. The simulation spends about a third of its time in the garbage collector. (Eep!). I would move across to simply storing x and y values, but a lot of the vector manipulation functions need to return new vectors. (Eg, add(), mult(), rotate(), lerp(), ... etc). If I store (x,y), I need a way to return two values from those functions. My ideas: - Try and use an object pool of vectors. It might be hard to track the lifetime of all the vectors the library uses, but I should be able to manually release most of them. - Make all the functions that return a vector instead store the (x,y) pair in a pair of global variables. Other functions can then copy the result back when they're done computing. That way, I can remove heap-stored vectors entirely; though my code will get super messy. - Manually inline a lot of the vector functions. Again, my code will get messier. What do you guys reckon? Are there any other options? My trivial vector implementation is here: https://github.com/josephg/Chipmunk-js/blob/master/lib/cpVect.js -J -- v8-users mailing list [email protected] http://groups.google.com/group/v8-users
