"MySQL server has gone away (%r)" % (e,))
pymysql.err.OperationalError: (2006, "MySQL server has gone away (TimeoutError(110, 'Connection timed out'))")

代碼中未在query操作及時close cursor，在每個連接中，均要有cursor.close() 和 conn.close()操作。即：

def db_execute(query):
     conn = MySQLdb.connect(*)
     cur = conn.cursor()
     cur.execute(query)
     res = cur.fetchall()
     cur.close()
     conn.close()
     return res

這樣的話會有性能問題，推薦使用SqlAlchemy.pool。那mysql中有辦法實現嗎？我們試試多線程和協程。

class MysqlConnect(object):
    """
    mysql connect 基類
    """

    def __init__(self, db_params=cmdb_test_params, maxconn=5):
        self.db_params = db_params
        self.maxconn = maxconn
        self.pool = Queue(maxconn)
        for i in range(maxconn):
            self.connect = self._connect()
            self.commit()
            self.cursor = self._cursor()

    def _connect(self):
        """
        mysql connect
        :return cursor:
        """
        key = ['host', 'port', 'user', 'password', 'database', 'charset']
        if not all([True if k in self.db_params else False for k in key]):
            raise Exception(list(self.db_params.keys()), "數據庫連接失敗，請檢查配置參數")
        try:
            conn = pymysql.connect(**self.db_params)
            conn.autocommit(True)
            self.pool.put(self.connect)
        except pymysql.Error as e:
            logutil.Logger().error(e)
            traceback.print_exc()
            raise pymysql.Error("連接數據庫失敗 %s" % e)
        self.connect = conn
        return self.connect

    def _cursor(self):
        if self.connect:
            conn = self.pool.get()
            self.cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
        else:
            self._connect()
            conn = self.pool.get()
            self.cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
        return self.cursor

    def close(self):
        if self.connect:
            self.cursor.close()  # 關閉遊標，未及時close時，連接池被占用 error code 2006
            self.pool.put(self.connect)
            self.connect = None

    def commit(self):
        try:
            if self.connect:
                self.connect.autocommit(True)
        except pymysql.Error as e:
            logutil.Logger().error(e)
            traceback.print_exc()
            raise pymysql.Error("數據庫提交失敗 %s" % e)
        finally:
            self.close()

    def rollback(self):
        try:
            if self.connect:
                self.connect.rollback()
        except pymysql.Error as e:
            logutil.Logger().error(e)
            traceback.print_exc()
            raise pymysql.Error("數據庫回滾失敗 %s" % e)
        finally:
            if self.connect:
                self.close()

    def __del__(self):
        self.commit()

    def query_execute(self, sql):
        try:
            if self.connect is None:
                self._connect()
                self._cursor()
            result_list = []
            self.cursor.execute(sql)
            for row in self.cursor.fetchall():
                result_list.append(list(row))
            return result_list
        except pymysql.Error as e:
            logutil.Logger().error(e)
            traceback.print_exc()
            raise pymysql.Error("數據庫查詢失敗 %s" % e)
        finally:
            if self.connect:
                self.close()

    def dml_execute(self, sql):
        try:
            if self.connect is None:
                self._connect()
                self._cursor()
            if self.cursor is None:
                self._cursor()
            self.cursor.execute(sql)
            self.commit()
        except pymysql.Error as e:
            logutil.Logger().error(e)
            traceback.print_exc()
            self.rollback()
            raise pymysql.Error("數據庫執行dml失敗 %s" % e)
        finally:
            self.close()

    def dml_execute_many(self, sql):
        try:
            if self.connect is None:
                self._connect()
                self._cursor()
            if self.cursor is None:
                self._cursor()
            self.cursor.executemany(sql)
            self.commit()
        except pymysql.Error as e:
            logutil.Logger().error(e)
            traceback.print_exc()
            self.rollback()
            raise pymysql.Error("數據庫執行dml失敗 %s" % e)
        finally:
            self.close()

    def testmysqldb(self,ip,user,password,dbname,Strsql):
        try:
            self.connect = pymysql.connect(host=ip,user=user,passwd=password,charset='utf8')
            self.connect.select_db(dbname)
            self.query_execute(Strsql)
            return True
        except Exception as e:
            print(("Error %d :%s" %(e.args[0],e.args[1])))
            return False

如何實現python的mysql連接池並加入緩存過期