JRuby Concurrency Bug in ShellLauncher

jruby_concurrency_bug.rb

# rvm use jruby-1.6.7
# export JRUBY_OPTS=--1.9
# jruby jruby_concurrency_bug.rb

puts "JRUBY_VERSION: #{JRUBY_VERSION}"
puts "JRUBY_OPTS: #{ENV["JRUBY_OPTS"]}"

popen_thread = Thread.new do
  20.times do |n|
    puts "Sleeping #{n}"
    IO.popen("sleep 1", :err=>[:child, :out]) do |stdout|
      stdout.each do |line| 
        puts "Output: #{line}"
      end
    end
    puts "Done sleeping #{n}"
  end
end

env_modify_thread = Thread.new do
  puts "Starting to modify env"
  50000.times do |n|
    ENV["var#{n}"] = "value #{n}"
  end
  puts "Done modifying env"
end

env_modify_thread.join
popen_thread.join

Results

JRUBY_VERSION: 1.6.7
JRUBY_OPTS: --1.9
Starting to modify env
Sleeping 0
Done sleeping 0
Sleeping 1
Exception in thread "RubyThread-1: jruby_bug.rb:4" java.lang.ArrayIndexOutOfBoundsException: 8495
	at org.jruby.util.ShellLauncher.getCurrentEnv(ShellLauncher.java:231)
	at org.jruby.util.ShellLauncher.popenShared(ShellLauncher.java:712)
	at org.jruby.util.ShellLauncher.popenShared(ShellLauncher.java:689)
	at org.jruby.util.ShellLauncher.popenShared(ShellLauncher.java:685)
	at org.jruby.util.ShellLauncher.popen(ShellLauncher.java:669)
	at org.jruby.RubyIO.popen19(RubyIO.java:3720)
	at org.jruby.RubyIO$s$0$1$popen19.call(RubyIO$s$0$1$popen19.gen:65535)
	at org.jruby.internal.runtime.methods.DynamicMethod.call(DynamicMethod.java:219)
	at org.jruby.runtime.callsite.CachingCallSite.callBlock(CachingCallSite.java:210)
	at org.jruby.runtime.callsite.CachingCallSite.callIter(CachingCallSite.java:221)
	at jruby_bug.block_1$RUBY$__file__(jruby_bug.rb:10)
	at jruby_bug$block_1$RUBY$__file__.call(jruby_bug$block_1$RUBY$__file__:65535)
	at org.jruby.runtime.CompiledBlock19.yield(CompiledBlock19.java:139)
	at org.jruby.runtime.Block.yield(Block.java:130)
	at org.jruby.RubyFixnum.times(RubyFixnum.java:256)
	at org.jruby.RubyFixnum$i$0$0$times.call(RubyFixnum$i$0$0$times.gen:65535)
	at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:302)
	at org.jruby.runtime.callsite.CachingCallSite.callBlock(CachingCallSite.java:144)
	at org.jruby.runtime.callsite.CachingCallSite.callIter(CachingCallSite.java:153)
	at jruby_bug.block_0$RUBY$__file__(jruby_bug.rb:8)
	at jruby_bug$block_0$RUBY$__file__.call(jruby_bug$block_0$RUBY$__file__:65535)
	at org.jruby.runtime.CompiledBlock19.yield(CompiledBlock19.java:163)
	at org.jruby.runtime.CompiledBlock19.call(CompiledBlock19.java:91)
	at org.jruby.runtime.Block.call(Block.java:89)
	at org.jruby.RubyProc.call(RubyProc.java:270)
	at org.jruby.RubyProc.call(RubyProc.java:224)
	at org.jruby.internal.runtime.RubyRunnable.run(RubyRunnable.java:95)
	at java.lang.Thread.run(Thread.java:680)

JRuby bug filed as http://jira.codehaus.org/browse/JRUBY-6603