jruby 9.0.3.0 (2.2.2) 2015-10-21 633c9aa Java HotSpot(TM) 64-Bit Server VM 24.45-b08 on 1.7.0_45-b18 +jit [darwin-x86_64]

It happens when my tests involve netdown.
Here is the code snippet:

    def read(bytes = nil, outbuf = nil)
      ret = ""
      loop do
        c = @chunks.shift
        ret << c if c && !c.empty?
        break if bytes && ret.size >= bytes
        if @producer.alive?
          @producer.resume                        # hangs at this line
        else
          break
        end
      end

      if outbuf
        # WARNING: Using outbuf = '' here DOES NOT work!
        outbuf.clear
        outbuf << ret
      end

      # Conform to IO#read(length[, outbuf]):
      # At end of file, it returns nil or "" depend on
      # length. ios.read() and ios.read(nil) returns
      # "". ios.read(positive-integer) returns nil.
      return nil if ret.empty? && !bytes.nil? && bytes > 0

      ret
    end

    def write(chunk)
      @chunks << chunk
      Fiber.yield
      self
    end

Here are the stack trace:

"Ruby-0-Thread-8: /Users/rockuw/Downloads/ruby-sdk/lib/aliyun/oss/upload.rb:51" daemon prio=5 tid=0x00007fd814529800 nid=0x5603 waiting on condition [0x0000700002252000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000007e3398298> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
at java.util.concurrent.ArrayBlockingQueue.take(ArrayBlockingQueue.java:374)
at org.jruby.ext.thread.Queue$1.run(Queue.java:59)
at org.jruby.ext.thread.Queue$1.run(Queue.java:56)
at org.jruby.RubyThread.executeTask(RubyThread.java:1352)
at org.jruby.ext.thread.Queue.pop(Queue.java:195)
at org.jruby.ext.thread.Queue.pop(Queue.java:164)
at org.jruby.ext.fiber.ThreadFiber.exchangeWithFiber(ThreadFiber.java:108)
at org.jruby.ext.fiber.ThreadFiber.resume(ThreadFiber.java:86)
at org.jruby.ext.fiber.ThreadFiber$INVOKER$i$0$0$resume.call(ThreadFiber$INVOKER$i$0$0$resume.gen)
at org.jruby.internal.runtime.methods.JavaMethod$JavaMethodN.call(JavaMethod.java:713)
at org.jruby.internal.runtime.methods.DynamicMethod.call(DynamicMethod.java:189)
at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:129)
at Users.rockuw.Downloads.ruby_minus_sdk.lib.aliyun.oss.http.invokeOther10:resume(/Users/rockuw/Downloads/ruby-sdk/lib/aliyun/oss/http.rb)
at Users.rockuw.Downloads.ruby_minus_sdk.lib.aliyun.oss.http.RUBY$block$read$0(/Users/rockuw/Downloads/ruby-sdk/lib/aliyun/oss/http.rb:57)
at java.lang.invoke.LambdaForm$DMH/1598639304.invokeStatic_LLLLLLL_L(LambdaForm$DMH)
at java.lang.invoke.LambdaForm$MH/1861629557.invokeExact_MT(LambdaForm$MH)
at org.jruby.runtime.CompiledIRBlockBody.commonYieldPath(CompiledIRBlockBody.java:70)
at org.jruby.runtime.MixedModeIRBlockBody.commonYieldPath(MixedModeIRBlockBody.java:99)
at org.jruby.runtime.IRBlockBody.yieldSpecific(IRBlockBody.java:67)
at org.jruby.runtime.Block.yieldSpecific(Block.java:116)
at org.jruby.RubyKernel.loop(RubyKernel.java:1291)
at org.jruby.RubyKernel$INVOKER$s$0$0$loop.call(RubyKernel$INVOKER$s$0$0$loop.gen)
at org.jruby.internal.runtime.methods.JavaMethod$JavaMethodZeroBlock.call(JavaMethod.java:494)
at org.jruby.runtime.callsite.CachingCallSite.callBlock(CachingCallSite.java:77)
at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:83)
at org.jruby.ir.instructions.CallBase.interpret(CallBase.java:419)
at org.jruby.ir.interpreter.InterpreterEngine.processCall(InterpreterEngine.java:322)
at org.jruby.ir.interpreter.StartupInterpreterEngine.interpret(StartupInterpreterEngine.java:77)
at org.jruby.ir.interpreter.InterpreterEngine.interpret(InterpreterEngine.java:83)
at org.jruby.internal.runtime.methods.MixedModeIRMethod.INTERPRET_METHOD(MixedModeIRMethod.java:197)
at org.jruby.internal.runtime.methods.MixedModeIRMethod.call(MixedModeIRMethod.java:183)
at org.jruby.internal.runtime.methods.DynamicMethod.call(DynamicMethod.java:197)
at org.jruby.RubyClass.finvoke(RubyClass.java:756)