20 engineers on Hacker News describe using JRuby first-hand: 5 endorse it, 4 regret it, 1 are mixed.
“it effectively became a black box that few could improve and even worse to test. As result, those portions had to be rewritten”
regret · production · nunobrito · 2025-09-07 · source ↗ · wrong label?“I've tried to support jruby along with MRI, but it requires jumping through a lot more hoops.”
regret · personal · coldnebo · 2016-12-02 · source ↗ · wrong label?“We're using JRuby in some core projects and it's great.”
endorse · production · magicdream · 2015-07-23 · source ↗ · wrong label?“I'm not particularly eager to keep testing JRuby. Maybe somebody will solve those problems.”
regret · personal · pmontra · 2015-07-23 · source ↗ · wrong label?“This isn't true on JRuby, where Ruby threads are 1:1 with JVM threads (which are in turn 1:1 with native threads) that execute in parallel on multiple cores.”
endorse · production · bascule · 2013-08-06 · source ↗ · wrong label?“our rails app used jruby and was pretty large so it took a minute or so to restart the server”
regret · production · ratbeard · 2013-07-12 · source ↗ · wrong label?“Nowadays we run in JRuby and things are quite a bit better.”
endorse · production · nirvdrum · 2013-06-04 · source ↗ · wrong label?“We use JRuby for a one of our backend applications in production, but we develop them with plain MRI Ruby.”
endorse · production · ghostganz · 2013-03-13 · source ↗ · wrong label?“In this case JRuby is clearly better because we run it in threadsafe mode.”
endorse · production · jshen · 2011-11-14 · source ↗ · wrong label?“While I've put JRuby in production for some smaller, non-Rails codebases that used JVM libraries, I've tried to run some non-trivial Rails applications on JRuby and it's just too slow”
mixed · production · rbranson · 2011-09-25 · source ↗ · wrong label?“actively using JRuby in production for a number of years”
neutral · production · skunkworker · 2021-11-19 · source ↗ · wrong label?“we moved to JRuby running on the same architecture as the rest of our apps”
neutral · production · mcguire · 2016-05-24 · source ↗ · wrong label?“how I should handle this as someone using JRuby in production”
neutral · production · Confusion · 2015-07-23 · source ↗ · wrong label?“FI was JRuby; as part of the naming switchover and product overhaul ... we switched it over to MRI in late 2011.”
neutral · production · holman · 2015-07-22 · source ↗ · wrong label?“Previously, we had been using JRuby deployed on Resin, and the results put that JRuby+Rails combination slightly slower than plain Ruby+Rails.”
neutral · personal · bhauer · 2013-12-26 · source ↗ · wrong label?“you get solutions like JRuby (built on the JVM), which provide for threads”
neutral · production · kyledrake · 2011-12-18 · source ↗ · wrong label?“We run heavily-threaded code in jruby in production, but we also test on MRI”
neutral · production · regularfry · 2011-10-04 · source ↗ · wrong label?“Sometimes you want to have multiple ruby versions (e.g. MRI for app and JRuby for memory heavy script)”
neutral · personal · xentronium · 2011-08-11 · source ↗ · wrong label?“but with small Clojure and JRuby experiments”
neutral · personal · mark_l_watson · 2010-11-21 · source ↗ · wrong label?“most of our JRuby stuff refuses to run on OSX. Some of the libraries we use are linux only.”
neutral · production · epochwolf · 2010-10-22 · source ↗ · wrong label?