import osimport sys import timeimport tornado.httpserverimport tornado.ioloopimport tornado.optionsimport tornado.webimport tornado.genfrom tornado.concurrent import run_on_executorfrom concurrent.futures import ThreadPoolExecutorfrom tornado.options import define, optionsclass HasBlockTaskHandler(tornado.web.RequestHandler):    executor = ThreadPoolExecutor(20)   #起线程池，由当前RequestHandler持有        @tornado.gen.coroutine    def get(self):        strTime = time.strftime("%Y-%m-%d %H:%M:%S")        print "in get before block_task %s" % strTime        result = yield self.block_task(strTime)        print "in get after block_task"        self.write("%s" % (result))    @run_on_executor    def block_task(self, strTime):        print "in block_task %s" % strTime        for i in range(1, 16):            time.sleep(1)            print "step %d : %s" % (i, strTime)        return "Finish %s" % strTimeif __name__ == "__main__":    tornado.options.parse_command_line()    app = tornado.web.Application(handlers=[(r"/sleep", HasBlockTaskHandler)], autoreload=False, debug=False)    http_server = tornado.httpserver.HTTPServer(app)    http_server.listen(8888)    tornado.ioloop.IOLoop.instance().start()