Merge pull request #56 from Telmate/master

Fix a bug in jruby env where pid is not a valid pid.

Author: thibaudgg

lib/rb-fsevent/fsevent.rb

@@ -52,14 +52,23 @@ def run
 
   def stop
     unless @pipe.nil?
-      Process.kill('KILL', @pipe.pid)
+      Process.kill('KILL', @pipe.pid) if process_running?(@pipe.pid)
       @pipe.close
     end
   rescue IOError
   ensure
     @running = false
   end
 
+  def process_running?(pid)
+    begin
+      Process.kill(0, pid)
+      true
+    rescue Errno::ESRCH
+      false
+    end
+  end
+
   if RUBY_VERSION < '1.9'
     def open_pipe
       IO.popen("'#{self.class.watcher_path}' #{options_string} #{shellescaped_paths}")