diff --git a/dubbo/common/constants.py b/dubbo/common/constants.py
index 4e42745..5223bac 100644
--- a/dubbo/common/constants.py
+++ b/dubbo/common/constants.py
@@ -40,3 +40,8 @@
 TIMEOUT_IDLE = 60
 # 连接允许的最多的超时次数
 TIMEOUT_MAX_TIMES = 3
+
+# 数据的头部大小为16个字节
+# 读取的数据类型：1 head; 2 error_body; 3 common_body;
+# 头部信息不存在invoke_id，所以为None
+DEFAULT_READ_PARAMS = 16, 1, None
diff --git a/dubbo/connection/connections.py b/dubbo/connection/connections.py
index 9cabf3e..8899750 100644
--- a/dubbo/connection/connections.py
+++ b/dubbo/connection/connections.py
@@ -9,7 +9,7 @@
 from dubbo.codec.encoder import Request
 from dubbo.codec.decoder import Response, parse_response_head
 from dubbo.common.constants import CLI_HEARTBEAT_RES_HEAD, CLI_HEARTBEAT_TAIL, CLI_HEARTBEAT_REQ_HEAD, \
-    TIMEOUT_CHECK_INTERVAL, TIMEOUT_IDLE, TIMEOUT_MAX_TIMES
+    TIMEOUT_CHECK_INTERVAL, TIMEOUT_IDLE, TIMEOUT_MAX_TIMES, DEFAULT_READ_PARAMS
 from dubbo.common.exceptions import DubboResponseException, DubboRequestTimeoutException
 from dubbo.common.util import get_invoke_id
 
@@ -26,6 +26,7 @@
         self.client_heartbeats = {}
         # 创建连接的锁
         self.conn_lock = threading.Lock()
+        # 用于在数据读取完毕之后唤醒主线程
         self.conn_events = {}
 
         reading_thread = threading.Thread(target=self._read_from_server)
@@ -37,6 +38,13 @@
         scanning_thread.start()
 
     def get(self, host, request_param, timeout=None):
+        """
+        执行远程调用获取数据
+        :param host:
+        :param request_param:
+        :param timeout:
+        :return:
+        """
         conn = self._get_connection(host)
         request = Request(request_param)
         request_data = request.encode()
@@ -115,44 +123,15 @@
             next_read_type   下一次读取需要读取的数据类型
             invoke_id        此次调用的id
         """
-        host = conn.remote_host()
-
         # 关闭连接
         if not data:
+            host = conn.remote_host()
             logger.debug('{} closed by remote server'.format(host))
             self._delete_connection(conn)
             return 0, 0, 0
 
         if data_type == 1:
-            try:
-                heartbeat, body_length = parse_response_head(data)
-            except DubboResponseException as e:  # 这里是dubbo的内部异常，与response中的业务异常不一样
-                logger.exception(e)
-                body_length = unpack('!i', data[12:])[0]
-                # 重新设置invoke_id
-                invoke_id = unpack('!q', data[4:12])[0]
-                # 下一次需要读取错误的响应体
-                return body_length, 2, invoke_id
-            # 远程主机发送的心跳请求数据包
-            if heartbeat == 2:
-                logger.debug('❤ request  -> {}'.format(conn.remote_host()))
-                msg_id = data[4:12]
-                heartbeat_response = CLI_HEARTBEAT_RES_HEAD + list(msg_id) + CLI_HEARTBEAT_TAIL
-                conn.write(bytearray(heartbeat_response))
-                # 下一次继续读取新的头部数据
-                return 16, 1, None
-            # 远程主机发送的心跳响应数据包
-            elif heartbeat == 1:
-                logger.debug('❤ response -> {}'.format(conn.remote_host()))
-                self.client_heartbeats[host] -= 1
-                # 下一次继续读取新的头部数据
-                return 16, 1, None
-            # 普通的数据包
-            else:
-                # 重新设置invoke_id
-                invoke_id = unpack('!q', data[4:12])[0]
-                # 下一次读取正常的响应体
-                return body_length, 3, invoke_id
+            return self._parse_head(data, conn)
         elif data_type == 2:
             res = Response(data)
             error = res.read_next()
@@ -160,14 +139,52 @@
             self.results[invoke_id] = DubboResponseException('\n{}'.format(error))
             self.conn_events[invoke_id].set()
             # 下一次继续读取新的头部数据
-            return 16, 1, None
+            return DEFAULT_READ_PARAMS
         elif data_type == 3:
             self._parse_response(invoke_id, data)
             # 下一次继续读取新的头部数据
-            return 16, 1, None
+            return DEFAULT_READ_PARAMS
         else:
             raise RuntimeError('Unknown data type {}.'.format(data_type))
 
+    def _parse_head(self, data, conn):
+        """
+        对dubbo响应的头部信息进行解析
+        :param data:
+        :param conn:
+        :return:
+        """
+        try:
+            heartbeat, body_length = parse_response_head(data)
+        except DubboResponseException as e:  # 这里是dubbo的内部异常，与response中的业务异常不一样
+            logger.exception(e)
+            body_length = unpack('!i', data[12:])[0]
+            # 获取响应的invoke_id
+            invoke_id = unpack('!q', data[4:12])[0]
+            # 下一次需要读取错误的响应体
+            return body_length, 2, invoke_id
+        # 远程主机发送的心跳请求数据包
+        if heartbeat == 2:
+            logger.debug('❤ request  -> {}'.format(conn.remote_host()))
+            msg_id = data[4:12]
+            heartbeat_response = CLI_HEARTBEAT_RES_HEAD + list(msg_id) + CLI_HEARTBEAT_TAIL
+            conn.write(bytearray(heartbeat_response))
+            # 下一次继续读取新的头部数据
+            return DEFAULT_READ_PARAMS
+        # 远程主机发送的心跳响应数据包
+        elif heartbeat == 1:
+            logger.debug('❤ response -> {}'.format(conn.remote_host()))
+            host = conn.remote_host()
+            self.client_heartbeats[host] -= 1
+            # 下一次继续读取新的头部数据
+            return DEFAULT_READ_PARAMS
+        # 普通的数据包
+        else:
+            # 获取响应的invoke_id
+            invoke_id = unpack('!q', data[4:12])[0]
+            # 下一次读取正常的响应体
+            return body_length, 3, invoke_id
+
     def _parse_response(self, invoke_id, body):
         """
         对dubbo的响应数据进行解析
@@ -215,22 +232,36 @@
         while 1:
             starting = time.time()
             for host in self._connection_pool.keys():
-                conn = self._connection_pool[host]
-                if time.time() - conn.last_active > TIMEOUT_IDLE:
-                    if self.client_heartbeats[host] >= TIMEOUT_MAX_TIMES:
-                        self._delete_connection(conn)
-                        conn.close()  # 客户端主动关闭连接
-                        logger.debug('{} closed by client'.format(host))
-                        continue
-                    self.client_heartbeats[host] += 1
-                    invoke_id = list(bytearray(pack('!q', get_invoke_id())))
-                    req = CLI_HEARTBEAT_REQ_HEAD + invoke_id + CLI_HEARTBEAT_TAIL
-                    conn.write(bytearray(req))
+                self._check_conn(host)
             ending = time.time()
             time_delta = ending - starting
             if time_delta < TIMEOUT_CHECK_INTERVAL:
                 time.sleep(TIMEOUT_CHECK_INTERVAL - time_delta)
 
+    def _check_conn(self, host):
+        """
+        对连接进行检查，查看是否超时或者已经达到最大的超时次数
+        :param host:
+        :return:
+        """
+        conn = self._connection_pool[host]
+        # 如果未达到最大的超时时间，则不进行任何操作
+        if time.time() - conn.last_active <= TIMEOUT_IDLE:
+            return
+
+        # 达到最大的超时次数，移除此连接
+        if self.client_heartbeats[host] >= TIMEOUT_MAX_TIMES:
+            self._delete_connection(conn)
+            conn.close()  # 客户端主动关闭连接
+            logger.debug('{} closed by client'.format(host))
+
+        # 未达到最大的超时次数，超时次数+1且发送心跳包
+        else:
+            self.client_heartbeats[host] += 1
+            invoke_id = list(bytearray(pack('!q', get_invoke_id())))
+            req = CLI_HEARTBEAT_REQ_HEAD + invoke_id + CLI_HEARTBEAT_TAIL
+            conn.write(bytearray(req))
+
 
 class SelectConnectionPool(BaseConnectionPool):
     """
@@ -281,21 +312,16 @@
         self.__sock = sock
         self.__host = '{0}:{1}'.format(host, port)
 
-        # 数据的头部大小为16个字节
-        self.read_length = 16
-        # 读取的数据类型：1 head; 2 error_body; 3 common_body;
-        self.read_type = 1
-        self.invoke_id = None
+        self.read_length, self.read_type, self.invoke_id = DEFAULT_READ_PARAMS
         self.read_buffer = []
-
         self.write_buffer = []
+        self.write_lock = threading.Lock()
 
         self.last_active = time.time()
 
-        self.write_lock = threading.Lock()
-
     def fileno(self):
         """
+        Get file descriptor
         https://stackoverflow.com/a/39328021/4614538
         :return:
         """