python字符串连接效率比较（使用+连接）

#coding=utf8import cStringIOimport StringIOimport timevalues = []items = ['1,2,31,2,31,2,31,2,3'] * 10000000#print itemsst = float(time.time())for i in items:    values.append(i)news = ''.join(values)print len(news)print 'list append cost time:%s'%(float(time.time()) - st)strio = cStringIO.StringIO()st = float(time.time())for j in items:    strio.write(j)print len(strio.getvalue())print 'cStringIO cost time:%s'%(float(time.time()) - st)strio = StringIO.StringIO()st = float(time.time())for j in items:    strio.write(j)print len(strio.getvalue())print 'StringIO cost time:%s'%(float(time.time()) - st)