cpyext is PyPy's subsystem which provides a compatibility layer to compile and run CPython C extensions inside PyPy. Often people ask why a particular C extension doesn't work or is very slow on PyPy. Usually it is hard to answer without going into technical details. The goal of this blog post is to explain some of these technical details, so that we can simply link here instead of explaining agai
![Inside cpyext: Why emulating CPython C API is so Hard](https://cdn-ak-scissors.b.st-hatena.com/image/square/f4b131bf694a6bff9073f07729aae047f42be47a/height=288;version=1;width=512/https%3A%2F%2Fblogger.googleusercontent.com%2Fimg%2Fb%2FR29vZ2xl%2FAVvXsEhQbnPzsohH78T0ZgGQn3_HZgh00mxdpxwteuJbM2DSxSp6CTmDXnEp2lRQJQ42LdOxhfxjVGhfvJ7F8T1Y-GuhtKKMeqAkhjYGeXa856v1k4FafXKtgqEWwWesCCaVVAWLvlZUHgJ9cJo%2Fw1200-h630-p-k-no-nu%2Fpypy58.png)