journal of recreational computer science


FreeBSD + Java 7 + JRuby 1.7.0

21 Oct 2012

So, I've just installed a fresh version of jruby 1.7.0 via rvm on my FreeBSD VPS and immediately wanted to see what would fail in my small app I was working on. Turns out I got this cryptic error:

WARNING:  Error fetching data:
  IOError: Function not implemented (
ERROR: While executing gem ... (Gem::RemoteFetcher::FetchError)
  IOError: Function not implemented (

Huh? That doesn't make any sense... fortunately dmesg came to the rescue with this, more helpful message:

linux: pid 23484 (java): syscall epoll_create not implemented

Ah, right - I'm running in Linux emulation mode, the simplest (?) way to get Java running on FreeBSD. Fortunately for me it looks like the Java runtime has an alternative implementation of I/O based on poll(2). There are two ways to force the runtime to do that by setting the appropriate system property - either via the command line:

ruby -S irb

or programatically:

> java.lang.System.setProperty('java.nio.channels.spi.SelectorProvider','')
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