非常感谢这个片段，我不得不对它进行一些修改，以便直接使用sqlalchemy.orm：如果它对任何人都有用的话。。

from sqlalchemy.exc import OperationalError, StatementError
from sqlalchemy.orm.query import Query as _Query
from time import sleep

class RetryingQuery(_Query):
    __max_retry_count__ = 3

    def __init__(self, *args,**kwargs):
        super().__init__(*args,**kwargs)

    def __iter__(self):
        attempts = 0
        while True:
            attempts += 1
            try:
                return super().__iter__()
            except OperationalError as ex:
                if "server closed the connection unexpectedly" not in str(ex):
                    raise
                if attempts <= self.__max_retry_count__:
                    sleep_for = 2**(attempts - 1)
                    logging.error(
                        "/!\ Database connection error: retrying Strategy => sleeping for {}s"
                    " and will retry (attempt #{} of {}) \n Detailed query impacted: {}".format(
                        sleep_for, attempts, self.__max_retry_count__, ex)
                )
                    sleep(sleep_for)
                    continue
                else:
                    raise
            except StatementError as ex:
                if "reconnect until invalid transaction is rolled back" not in str(ex):
                    raise
                self.session.rollback()

对于用法：将选项传递给sessionmaker：

sqlalchemy.orm.sessionmaker(bind=engine, query_cls=RetryingQuery)

我不得不稍微调整它，使之与postgres一起工作，它有一个不同的错误消息。我知道这个问题是有标签的 mysql ，但是通过搜索发现了这个问题（并且有完全相同的问题），所以可能会帮助某人。
我还得接住 StatementError: (sqlalchemy.exc.InvalidRequestError) Can't reconnect until invalid transaction is rolled back 在重试之前 flask 就爆炸了。
最后我让它指数退避，因为为什么不呢？

import logging
from flask_sqlalchemy import BaseQuery
from sqlalchemy.exc import OperationalError, StatementError
from time import sleep

class RetryingQuery(BaseQuery):
    __retry_count__ = 3

    def __init__(self, *args,**kwargs):
        super().__init__(*args,**kwargs)

    def __iter__(self):
        attempts = 0
        while True:
            attempts += 1
            try:
                return super().__iter__()
            except OperationalError as ex:
                if "server closed the connection unexpectedly" not in str(ex):
                    raise
                if attempts < self.__retry_count__:
                    sleep_for = 2**(attempts - 1)
                    logging.error(
                        "Database connection error: {} - sleeping for {}s"
                        " and will retry (attempt #{} of {})".format(
                            ex, sleep_for, attempts, self.__retry_count__
                        )
                    )
                    sleep(sleep_for)
                    continue
                else:
                    raise
            except StatementError as ex:
                if "reconnect until invalid transaction is rolled back" not in str(ex):
                    raise
                self.session.rollback()

显然地 sqlalchemy 有一个很好的自定义查询类的选项，这正是我所需要的。
类实现：

import logging
from flask_sqlalchemy import BaseQuery
from sqlalchemy.exc import OperationalError
from time import sleep

class RetryingQuery(BaseQuery):

    __retry_count__ = 3
    __retry_sleep_interval_sec__ = 0.5

    def __init__(self, *args,**kwargs):
        super().__init__(*args,**kwargs)

    def __iter__(self):
        attempts = 0
        while True:
            attempts += 1
            try:
                return super().__iter__()
            except OperationalError as ex:
                if "Lost connection to MySQL server during query" not in str(ex):
                    raise
                if attempts < self.__retry_count__:
                    logging.debug(
                        "MySQL connection lost - sleeping for %.2f sec and will retry (attempt #%d)",
                        self.__retry_sleep_interval_sec__, attempts
                    )
                    sleep(self.__retry_sleep_interval_sec__)
                    continue
                else:
                    raise

用法：

class BaseModel(Model):
    ...
    query_class = RetryingQuery
    ...

db = SQLAlchemy(model_class=BaseModel, query_class=RetryingQuery)

sqlalchemy还允许您聆听 engine_connect 在 connection 已创建。这使得实现悲观断开处理的自定义逻辑成为可能
下面的代码段实现了指数退避以供重试。它取自apache airflow的sqlalchemy utils：http://airflow.apache.org/docs/1.10.3/_modules/airflow/utils/sqlalchemy.html

@event.listens_for(engine, "engine_connect")
    def ping_connection(connection, branch):
        """
        Pessimistic SQLAlchemy disconnect handling. Ensures that each
        connection returned from the pool is properly connected to the database.

        http://docs.sqlalchemy.org/en/rel_1_1/core/pooling.html#disconnect-handling-pessimistic
        """
        if branch:
            # "branch" refers to a sub-connection of a connection,
            # we don't want to bother pinging on these.
            return

        start = time.time()
        backoff = initial_backoff_seconds

        # turn off "close with result".  This flag is only used with
        # "connectionless" execution, otherwise will be False in any case
        save_should_close_with_result = connection.should_close_with_result

        while True:
            connection.should_close_with_result = False

            try:
                connection.scalar(select([1]))
                # If we made it here then the connection appears to be healthy
                break
            except exc.DBAPIError as err:
                if time.time() - start >= reconnect_timeout_seconds:
                    log.error(
                        "Failed to re-establish DB connection within %s secs: %s",
                        reconnect_timeout_seconds,
                        err)
                    raise
                if err.connection_invalidated:
                    log.warning("DB connection invalidated. Reconnecting...")

                    # Use a truncated binary exponential backoff. Also includes
                    # a jitter to prevent the thundering herd problem of
                    # simultaneous client reconnects
                    backoff += backoff * random.random()
                    time.sleep(min(backoff, max_backoff_seconds))

                    # run the same SELECT again - the connection will re-validate
                    # itself and establish a new connection.  The disconnect detection
                    # here also causes the whole connection pool to be invalidated
                    # so that all stale connections are discarded.
                    continue
                else:
                    log.error(
                        "Unknown database connection error. Not retrying: %s",
                        err)
                    raise
            finally:
                # restore "close with result"
                connection.should_close_with_result = save_should_close_with_result