This post is the (long awaited, or at least long promised) third post in my series on Rayon’s parallel iterators. The previous two posts were some time ago, but I’ve been feeling inspired to push more on Rayon lately, and I remembered that I had never finished this blog post series. Here is a list of the other posts in the series. If you haven’t read them, or don’t remember them, you will want to do so before reading this one:

This post is the second post in my series on Rayon’s parallel iterators. The goal of this series is to explain how parallel iterators are implemented internally, so I’m going to be going over a lot of details and giving a lot of little code examples in Rust. If all you want to do is use parallel iterators, you don’t really have to understand any of this stuff. I’ve had a lot of fun designing this system, and I learned a few lessons about how best to use Rust (some of which I cover in the conclusions).

Since giving a talk about Rayon at the Bay Area Rust meetup, I’ve been working off and on on the support for parallel iterators. The basic idea of a parallel iterator is that I should be able to take an existing iterator chain, which operates sequentially, and easily convert it to work in parallel. As a simple example, consider this bit of code that computes the dot-product of two vectors: