scrapy中运行一段时间报错pymysql.err.InterfaceError: (0, '')

错误信息

   Traceback (most recent call last):
  File "/home/anaconda3/envs/python36/lib/python3.6/site-packages/twisted/python/threadpool.py", line 250, in inContext
    result = inContext.theWork()
  File "/home/anaconda3/envs/python36/lib/python3.6/site-packages/twisted/python/threadpool.py", line 266, in <lambda>
    inContext.theWork = lambda: context.call(ctx, func, *args, **kw)
  File "/home/anaconda3/envs/python36/lib/python3.6/site-packages/twisted/python/context.py", line 122, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/home/anaconda3/envs/python36/lib/python3.6/site-packages/twisted/python/context.py", line 85, in callWithContext
    return func(*args,**kw)
--- <exception caught here> ---
  File "/home/anaconda3/envs/python36/lib/python3.6/site-packages/twisted/enterprise/adbapi.py", line 474, in _runInteraction
    conn.rollback()
  File "/home/anaconda3/envs/python36/lib/python3.6/site-packages/twisted/enterprise/adbapi.py", line 52, in rollback
    self._connection.rollback()
  File "/home/anaconda3/envs/python36/lib/python3.6/site-packages/pymysql/connections.py", line 431, in rollback
    self._execute_command(COMMAND.COM_QUERY, "ROLLBACK")
  File "/home/anaconda3/envs/python36/lib/python3.6/site-packages/pymysql/connections.py", line 745, in _execute_command
    raise err.InterfaceError("(0, '')")
pymysql.err.InterfaceError: (0, '')

翻了一下日志信息，发现有一个特点，就是在报错之前的信息大多都是抓取listing的信息，而没有返回item，也没有item入库的日志打印，所以我怀疑是adbapi的连接池中的连接很久没有使用导致连接被mysql销毁，插入的时候失败，然后事务回滚，连接池中数据库连接异常导致回滚失败，最后得到这个报错信息。

我item pipeline中使用数据库连接方法为：

# pipeline默认调用
def process_item(self, item, spider):
    query = self.dbpool.runInteraction(self._conditional_insert, item)
    query.addErrback(self._handle_error, item, spider)
    return item

最后我修改了一下,每次插入数据的时候ping一下，如果重连失败就将整个数据库连接池初始化一遍，完整的代码为

class MyPipeline(object):

    def __init__(self, dbpool):
        self.dbpool = dbpool

    @classmethod
    def from_settings(cls, settings):
        dbpool = MysqlConnectionPool().dbpool()
        return cls(dbpool)

    # pipeline默认调用
    def process_item(self, item, spider):
        query = self.dbpool.runInteraction(self._conditional_insert, item)
        query.addErrback(self._handle_error, item, spider)
        return item

    def _handle_error(self, failue, item, spider):
        print(failue)

    def _conditional_insert(self, transction, item):
        tt = transction._connection._connection
        try:
            tt.ping()
        except:
            self.dbpool.close()
            self.dbpool = MysqlConnectionPool().dbpool()
        sql = """insert INTO `DOC_BASEINFO`(doc_type,author_org )
        VALUES (%s,%s)"""
        params = (
            item['doc_type'], item['author_org'])
        transction.execute(sql, params)