I was trying to find a good resource on how to have Kemal benefiting from Crystal’s parallelism support. I did some googling but I couldn’t find a resource on this. Do you know about any good material that covers this? Thanks

Kemal uses the standard libraries’ HTTP::Server module under the hood. All you should have to do is essentially just build your binary with -D preview_mt and that should be it. The number of worker threads defaults to 4 but an be controlled by the CRYSTAL_WORKERS env var. Just note that multithre…

Thanks a lot. I will give it a try. I want to update the version running on https://www.techempower.com/benchmarks/

The Techempower’s benchmarks already run in multiple processes via reuse_port: true. It’s highly unlikely the results would improve. If you do update benchmarks, please update all Crystal frameworks. It’s good to see apples to apples comparison.

[image] vlazar: It’s highly unlikely the results would improve. This is very true. In fact, not only would they not improve, but they may very well end up worse. Crystal is much more efficient across fibers in single-threaded mode than it is when multithreaded. It would use more CPU time to d…

In my benchmarks once you get past like 4 simultaneous workers then it starts to bottleneck on the GC, FWIW… [image] Multithreaded Crystal initial thoughts OK here’s some patches I found to speed it up a little but overall…couldn’t see much, except that past like 4-6 thr…

[image] Blacksmoke16: Just note that multithreading is still considered experimental, and some portions of Kemal may not be thread safe. Don’t even need to look at kemal. Stdlib’s HTTP:::Server is already not threadsafe. Multi-threading is really just a technology preview and not recommended …

aaah, I see your point. I will wait then until this is no longer a preview flag. There is no point on adding noise in those benchmarks. Thanks!

Crystal parallelism and Kemal

Help & Support

rogerdpack March 3, 2020, 3:35pm 6

In my benchmarks once you get past like 4 simultaneous workers then it starts to bottleneck on the GC, FWIW…

Topic		Replies	Views
Multithreaded Crystal initial thoughts	38	7928	February 21, 2024
Crystal multithreading support Crystal Contrib	40	3091	March 20, 2026
Timeline for multithreading support Crystal Contrib	31	2835	September 24, 2024
Multi-threading ceases past certain input values Help & Support	9	594	July 8, 2022
Crystal and parallelism Help & Support	7	668	February 10, 2025

Crystal parallelism and Kemal

Related topics