text: var fs = require('fs');
  
  var rs = fs.createReadStream('msg.txt',{highWaterMark: 32 * 1024});
  rs.on('readable',function(){
      console.log('------------readable-------------');
      var data;
      while(null != (data = rs.read())){
  
      }
  });
  rs.on('end',function(){
      console.log('end');
  });