Add benchmark with Fiber

Author: sue445

_benchmark/tarai.rb

@@ -6,6 +6,7 @@
 end
 
 require "benchmark/ips"
+require "fiber"
 
 # Build native extension before running benchmark
 Dir.chdir(File.join(__dir__, "..", "ruby", "testdata", "example")) do
@@ -38,6 +39,13 @@ def tarai(x, y, z) =
     end.each(&:take)
   }
 
+  # parallel version (with Fiber)
+  x.report("parallel (Fiber)"){
+    4.times.map do
+      Fiber.new { tarai(14, 7, 0) }
+    end.each(&:resume)
+  }
+
   # parallel version (with goroutine)
   x.report("parallel (goroutine)"){ Example::Benchmark.tarai_goroutine(14, 7, 0, 4) }