Currently running 4 JVM based solutions on 2 RPi's in our home. One is a fairly heavy one (OpenHAB 2), consuming 700 MB of memory. The others are simple importers (written in Scala), using around 50 MB each. It runs fast, is extremely stable (> 200 days uptime), very fast response times (< 100 ms), has a built-in dependency manager and is type-safe.

With this setup, I have aggregated more than 4 years of in-home data, ranging from radio-thermostats, 15 thermometers, continuous electricity usage, around 10 z-wave devices, 15 zigbee sensors, Philips Hue Lighting (8 bulbs, 8 switches), local weather updates, InfluxDB storage and a fairly complicated setup for climate control (including presence detection using OwnTracks / WiFi and operation of roller-shutters and sunscreens).

How is it bizarre? Java and Python are both pretty standard for devices like this since they don't require recompilation for ARM. And Java is more performant than Python in general.