I'm running my jruby app as a war under Tomcat 8.0.35.
Under 9.1.1.0 and 9.1.2.0 (i haven't seen the error on <= 9.1.0.0, yet) I will receive, upon war deployment:

LoadError: load error: ethon/curls/options -- java.lang.NullPointerException: null
require at org/jruby/RubyKernel.java:944
block in require at WEB-INF/vendor/bundle/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274
load_dependency at WEB-INF/vendor/bundle/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:240
require at WEB-INF/vendor/bundle/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274
at WEB-INF/vendor/bundle/gems/ethon-0.8.1/lib/ethon/curl.rb:2
require at org/jruby/RubyKernel.java:944

Now I thought this could be an ethon problem, but i've been using it a while and never saw this error (yet) up until trying 9.1.1.0/9.1.2.0.
In my testing to reproduce this, i am NOT hot deploying. I am stopping tomcat, removing the webapp dir, and starting tomcat every time.
@PetrKaleta mentioned that he was seeing this in issue #3680 under rake. I've only seen it once in rake upon building my webapp (out of a couple dozen builds), every other time it's on deployment.
It happens maybe once every 10 deployments.
Under suggestion from @enebo to enable ir.reading.debug I have posted my full log to:

https://gist.github.com/abiacco/897fb4829b1eb601670c09d9366c51f5

I do have a large log with ir.debug enabled as well. If requested, i prefer to provide that privately.

Thanks

-Tony

Environment

jruby 9.1.2.0 (2.3.0) 2016-05-26 7357c8f Java HotSpot(TM) 64-Bit Server VM 25.91-b14 on 1.8.0_91-b14 +jit [linux-x86_64]

CentOS release 6.7 (Final)
Tomcat 8.0.35
java server jre 8u91
warbler 2.0.3
bundler 1.12.5

Also tested on jruby 9.1.1.0 and java 8u77

Linux app-01.local 2.6.32-573.18.1.el6.x86_64 #1 SMP Tue Feb 9 22:46:17 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Expected Behavior

No NullPointerException and rack failure :)

Actual Behavior

Intermittent NullPointerException from ethon gem.