???

which jruby version did you use. a quick test with jruby-1.7.12 showed the
same results as mri-2.1

Maybe try a bigger number? It might depend on your time. I'm using jruby-1.7.3, and also noticed the problem on whatever version of jruby travis-ci uses.

$ ruby -v
jruby 1.7.3 (1.9.3p385) 2013-02-21 dac429b on Java HotSpot(TM) 64-Bit Server VM 1.7.0_45-b18 +indy [darwin-x86_64]

$ irb
irb(main):001:0> Time.now + 7819128400
=> 1677-09-21 13:53:37 -0752

hmm - that is fixed from jruby-1.7.5 onwards. 1.7.3 feels really old by now ;)

regarding travis I guess you have to report it to there. I did see travis running old jruby versions somewhere before.

I get different results from jruby-1.7.5 onwards, but not correct results.

MRI:
irb(main):001:0> Time.now + 78191284000
=> 4492-04-13 03:44:55 -0700

JRuby 1.7.13:
irb(main):001:0> Time.now + 78191284000
=> 2306-10-12 10:25:22 -0700

sorry - did not use big enough numbers to add ;)

I was using the smallest number possible that would show the overflow. Looks like JRuby 1.7.5, instead of overflowing and going negative, just reaches the max date and stops.

https://jira.codehaus.org/browse/JRUBY-7095 looks related.

I believe @joevandyk's analysis is correct and makes this bug still valid against JRuby 9.0.0.0

On MRI Time.now + 78191284000 goes to the year 4493 whereas on my 9k/JDK8 install it goes to the year 2307.

That ain't right

thanks @headius !