rb: Switch from read_nonblock to readpartial to make jruby happy


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@669024 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/rb/benchmark/fairness.rb b/lib/rb/benchmark/fairness.rb
index a032013..11a9f04 100644
--- a/lib/rb/benchmark/fairness.rb
+++ b/lib/rb/benchmark/fairness.rb
@@ -142,7 +142,7 @@
       next if rd.nil?
       rd.each do |fd|
         begin
-          @buffers[fd] << fd.read_nonblock(4096)
+          @buffers[fd] << fd.readpartial(4096)
         rescue EOFError
           @pool.delete fd
         end