Here is a pull request that makes the Elixir code closer to the code in Go and uses better defaults (for example, what Phoenix would have used): Make benchmarks with Elixir fairer by josevalim · Pull Request #370 · antonputra/tutorials · GitHub

The issue is not Postgrex, but rather the fact it is comparing Ecto (which would be akin to a ORM):

https://github.com/antonputra/tutorials/blob/59d29deeb57b1a81fe9c2c5e4dcb44e96c6bedb8/lessons/230/elixir-app/lib/app/router.ex#L62-L73

With something that directly sends INSERT commands over the connection:

https://github.com/antonputra/tutorials/blob/main/lessons/230/go-app/device.go#L30-L33

And if you are going to set up 500 database connections, I would at least split over a few connection pools (by setting pool_count). Otherwise you are likely making the pool the bottleneck.

Overall, I’d expect the Go to have better throughput, but there is definitely a bit of apples to oranges going on. I honestly don’t understand why benchmark authors do not ask for some community vetting before publishing.

Thanks for sharing. I am a bit surprised indeed the new round did not see any improvement, given my pull request yielded a 20-30% improvement locally. I cannot reproduce the failures from the first benchmark on my machine either, I even used a separate machine to push traffic locally and I get 80k req/s for Elixir vs 110k req/s in Go.

However, it is worth saying that it is 100% expected for Go to be faster than Elixir. After all, we are comparing a static imperative compiled language to a dynamic functional language running on a VM, so a reasonable difference (within the same order of magnitude) is expected. For example, TechEmpower main branch puts Go around 5x faster than Phoenix for single-query runs. I am mostly curious about the failure rate, which is not expected, but as far as I know, there is no way to reproduce the benchmarks and the production logs were not shared with us. So there isn’t much we can do at the moment.