Lice!

A collection of somewhat random thoughts.

Multithreaded rust on Threadripper

I recently ran some benchmarks on a Threadripper 3960X system and the results were surprising me quite a bit. Simplified, the throughput the benchmark recorded went down, from 341 MB/s on a MBP to 136 MB/s on a Threadripper desktop. Prior I had read Daniel Lemire's notes on the sub optimal performance for simdjson on Zen 2, which is heavily used in the benchmark, but the suggested drop were a few percent not half. Read more →

Dell XPS/Windows as a dev env

I've recently gotten a Dell XPS 15” 2-in-1 and started using it as a development environment for the last week. To be honest as a long term MacBook user I expected a rather disapointing experience but to my big surprise I do really like it so far. But enough of a preamble. Why I'm writing this? Because I figured that the mistakes I made, the hints I got all over the place would have really helped me if someone had collected them - so I do that now. Read more →

migrating to rebar3

A long journey from rebar2 to rebar3 Rebar 3 has recently started to surface out of alpha state and entered beta1, about time for the crazy people like me to abandon tried and tested tools to venture into the great vastness of the unknown! So with a backpack, hiking shoes, food for about a week and a direct line to the rebar3 IRC channel I set off to migrate sniffle from rebar2 to rebar3. Read more →

Postmortem of a interesting bug

Symptoms After a full network outage in a larger system (7 FiFo instances and, a few dozen of hypervisors, VM's in the 3 digit number) a small percentage of the VM's stored in FiFo lost information which package was assigned to them and which organization they belong to. Technical background As part of planned maintenance on the switching layer the entire network was taken down. Effectively cutting the communication between any two systems in the network. Read more →

Post-mortem of a failed support case.

Every now and then I check the link reports for Project FiFo to see what people think and write about it. Recently I stumbled about an article that oddly enough made me both proud and sad. It actually was a rather negative one, which is a shame, but on the other hand a project isn't mature until people care enough to complain. Yet even so it would be very easy to cast this aside as a ‘success’ in a strange manner, it still bothers me that someone is upset enough with FiFo to spend his time writing a longish blog article and write their own management software. Read more →

Backups with Project FiFo

With 0.4.3 FiFo introduces support for LeoFS and this allows for some quite nice new features. Most importantly it decouples FiFo's operations from storing big amounts of data which makes maintaining either of this much more sensible and scaling storage much more easy. Then again while nice that is not the important part, just storing datasets somewhere else does not make much of a difference for most users but what LoeFS allows FiFo to store much more data then would be good in the old setup. Read more →

A asynchronously GCed OR Set

Following the article about Asynchronous garbage collection with CRDTs I experimented with implementing the concept. The OR Set is a very nice data structure for this since it's rather simple and so is it's garbage! To garbage collect the OR Set we do the following, we take some of the elements of the remove set, and delete them from both the add and the remove set - this way we save the space for them and generate a new baseline. Read more →

Asynchronous garbage collection with CRDTs

So CRDTs are very very nice data structures awesome for eventual consistent applications like riak, or the components of Project-FiFo. So they have one big drawback, most of them collect garbage, and over time that can sum up to a lot making them pretty unpractical in many cases. Collecting this garbage is a bit tricky, since usually it means synchronising the data - which going back to the eventual consistent stuff prevents either A or P. Read more →

Happy birthday Project FiFo

Some might know it, some might not and some might not care but for what it's worth I'm the author of Project-FiFo (or most of it) and today is Project-FiFo's first birthday (since the domain registration) and I want to take this chance to look back to the past year and reflect, say thank you to all of you and take a look in the future. When I started Project FiFo a year ago it was more of a tiny hobby project and I could have sworn it would stand in row with all the other little open source projects no one would ever give a damn about. Read more →

FiFo + 80LOC of bash = 5 node riak cluster

The reason The question ‘why would I want at least 5 nodes’ comes up very often in the #riak IRC channel, there is a good explanation. But that's boring, no one likes reading manuals, we, as engineers, like to try things out (aka. break stuff). Only downside with that is that we need to set things up before we can break them, or even worst need to un-break it later to try out different things (aka. Read more →