Viewing profile — tychver

Running T-Mobile's Erlang powered LTE network.

Sure they can. There’s a separate shared heap which uses atomic ref counting.

Did you check stack overflow jobs? What people are currently earning and what people are openly offering now has diverged quite a bit just in 18 months or so. It’s hurting the smal…

Berlin is a bit odd because of the huge changes in the last few years in companies starting offices here and the influx of VC funding. SoundCloud for example, had a bunch of engine…

Erlang has a really nice solution here by using a separate heap per Erland "process", and because they're owned by that process, can do a copying/compacting GC without having to ta…

Go merely adopts a different strategy which quietly fucks you in a different set of circumstances: https://news.ycombinator.com/item?id=15823683

Yeah, it mostly happens when you have a server which runs an abnormally large task or payload, causes the heap to grow, and does it in a way that Go can't release the memory back t…

Go trades the complexity of a compacting GC for forcing you to restart the app regularly if you have a workload with plenty of heap allocation.

I would also say the same if you host a Ruby or Python app, or anything using forking really. Similar to the issues you had with Redis, the kernel change to THP on by default total…

Do you mean: "take a few thousand rows and map them to a different data structure"? Because I benchmarked that recently and mapping 16,000 rows of GPS points using haversine distan…

500MB per worker is totally standard. What happens is a job causes a huge array or hash to be allocated, and after it‘s finished the memory can’t be returned to the OS due to heap …

The class definitions will be a tiny fraction of memory usage. A template Rails app memory usage only has about 20% managed by Ruby. The rest is the VM, C libraries, maybe long str…

Nah, unfortunately simply moving the GC bits from the object itself to bitmap in the page header made Ruby CoW friendlier but not CoW friendly! Each Ruby page is 4x OS pages on Lin…

Ruby is actually pretty good in this regard. If you define your module or class anonymously, but give it a name using a constant, Ruby will GC it when possible. The standard way of…

This was probably true 10 years ago, but these days it's basically FUD. Since then Ruby improved performance something like 5-80x from 1.8 to 2.5 and moved from an interpreted lang…

This is basically my job at ChartMogul and we've pretty much solved this problem. The two biggest issues for us were: Ruby prefers to grow the heap really quickly rather than spend…

You should really only need one process per core, plus a few thread per process. Obviously, this is a problem on Heroku where they give you 8 "cores" but only 512mb of RAM per 1x d…

Yes, but you only need one process per core, just like NodeJS. Since 1.9 you can use real OS threads to achieve parallel IO, and certain parallel computations which can proceed wit…

There's nothing really that special about Goroutines. Ruby also introduced Fibres in 2007. There's been some discussion of adding a more automatic M:N threading model to Ruby 3.

Patrick, on the 2.6+ Linux kernels, is there a significant difference between threads and processes? It seems like both threads and processes are created via clone and the only dif…

Yeah, that'll do it! C extensions are a core part of Ruby. A big chunk of the std lib is implemented in C. You shouldn't be afraid of writing a tiny bit of C. Ruby and Python are s…

Using Haversine distance increases it to only 13ms. I'm not sure why your Python implementation is so slow? In the real world, things like haversine are implemented as C extensions…

The whole Ruby VM only takes ~50ms to start, so that sounds a bit slow. I wrote a quick version in Ruby and it only takes 5ms: https://gist.github.com/jamatthews/d910a2b39c87a87126…

Not for almost a decade. Ruby web servers and job processing frameworks have used forking out of the box since the release of Phusion Passanger 2 in 2008 and Resque in 2009.

Forking 10 processes does not use 10x the memory of a single process starting 10 threads. It's actually almost identical. Both are implemented by the kernel using clone(). Many old…