Category Archive: Experiments

Mar 17

Docker, Cgroups, Memory Constraints, and Java: A Cautionary Tale, or Here be Reapers (sometimes)


TL;DR: Java and cgroups/Docker memory constraints don’t always behave as you might expect. Always explicitly specify JVM heap sizes. Also be aware that kernel features may not be enabled. And Linux… lies. I’ve recently discovered an interesting “quirk” in potential interactions between Java, cgroups, Docker, and the kernel which can cause some surprising results. Unless …

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Oct 02

Multifarious v2

While at a DevOps Birds of a Feather session at Ohio Linux Fest today I was describing to John Willis (@botchagalupe) my experiments with Docker and the Pi Swarm. Along the way, I mentioned that I’d gotten heterogenous docker swarms working using Powerstrip — aka Multifarious, first described in Heterogenous Docker Swarms Teaser. In so …

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Apr 28

Heterogenous Docker Swarms Teaser

Note: This is all very experimental; Docker does not support any architecture other than X86_64. The last few evenings I’ve been working on Mulitifarious, a means of creating heterogenous Docker Swarms. I’d previously found that I can create a swarm with heterogenous members — a swarm which has, say, X86_64 and Raspberry Pi members. The …

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