Bah, why does the stackless mailing server not set the header to respond to the stackless mailing list instead of responding to the mail sender, that needs to be fixed...
Message I sent is below: On Wed, Aug 26, 2009 at 3:31 AM, Dan Sanduleac<[email protected]> wrote: > Hi, > > I'm trying to compare different Python-C wrapping techniques to see which > would be faster and also more suited to game development. > I'm using Stackless Python 2....@74550 / GCC 4.3.3, and boost 1.39.0 on > Ubuntu 9.04. I implemented a simple Vec3 (3D vector) class in C++ and > wrapped it with boost::python. All it does is multiplications and additions, > so it implements just two operators for python. > The thing is, it proves to be kind of slow compared to an equivalent > Cython/Pyrex code. I think it should run faster than Cython code. > (Note: Cython is not an abbreviation for C/Python API) > I compiled the python library from Boost, in release mode, and then linked > the vec3 module, whose code is provided below, to the compiled boost::python > library. (I used -O2 when compiling the vec3 module) > > The testing goes like this: each "tick", 10000 objects update their > position, according to their velocity and timedelta since last "tick", and > I'm measuring the average time a tick takes to complete. > On my machine doing this with Cython takes ~0.026 sec/tick, while doing it > with boost.python takes like 0.052 sec/tick > (The overhead introduced by python's iterating through the list of objects > each tick is about 0.01 sec) > During one tick, for each object, python runs this: "self.position += > self.velocity * time_delta", > where position and velocity are instances of Vec3. > > I was hoping for better results than with Cython, by using Boost. Am I doing > something wrong? > > > > Source code: > vec3.cpp > ========== > #include <boost/python.hpp> > using namespace boost::python; > > class Vec3 { > > float x, y, z; > > public: > Vec3(float x, float y, float z); > Vec3 &operator*=(float scalar); > Vec3 operator*(float scalar) const; > Vec3 &operator+=(const Vec3 &who); > // that `const Vec3` is REALLY needed, unless you want error monsoon to > come down > }; > > // === boost:python wrapper === > // publish just += and * to python > > BOOST_PYTHON_MODULE(vec3) > { > class_<Vec3>("Vec3", init<float, float, float>()) > .def(self += self) > .def(self * float()) > ; > } > > // === implementation === > > Vec3::Vec3(float x, float y, float z) { > this->x = x; > this->y = y; > this->z = z; > } > > Vec3 & Vec3::operator*=(float scalar) { > this->x *= scalar; > this->y *= scalar; > thiz->z *= scalar;a > } > > Vec3 Vec3::operator*(float scalar) const { > return Vec3(*this) *= scalar; > } > > Vec3 & Vec3::operator+=(const Vec3 &who) { > this->x += who.x; > this->y += who.y; > this->z += who.z; > return *this; > } > > ============================================== > vec3.pyx (cython code, for reference) > =========================== > cdef class Vec3: > > cdef readonly double x, y, z > > def __cinit__(Vec3 self, double x, double y, double z): > self.x, self.y, self.z = x, y, z > > # operator * > def __mul__(Vec3 self, double arg): > return Vec3(self.x*arg, self.y*arg, self.z*arg) > > # operator += > def __iadd__(Vec3 self, Vec3 arg): > #if not isinstance(arg, Vec3): > # return NotImplemented > self.x += arg.x > self.y += arg.y > self.z += arg.z > return self That is because Boost.Python is designed to be an easy to use, safe, and powerful binder, not fast. It is good to bind things that are long lived, not something as quick as simple operations like an addition and so forth, the overhead of the call will be so much higher then the actual operation. Something like Cython does not have that limitation, although it produced slower code, the binding overhead does not exist. _______________________________________________ Stackless mailing list [email protected] http://www.stackless.com/mailman/listinfo/stackless
