MySQLdb has the same problem.
So, no concurrent, I just use engine(with default connection pool) execute.
Then, how to work around the problem, for my query operation, if catch this
exception, query again?
在 2014年3月27日星期四UTC+8下午11时42分19秒，Michael Bayer写道：
>
>
> On Mar 27, 2014, at 9:14 AM, Ni Wesley <nis...@gmail.com <javascript:>>
> wrote:
>
> It's not happening everytime.
>
> And I am not using mysql-python, instead, I use pymysql.
>
> So, the root cause is connection in bad state?
> How to fix or work around from sqlalchemy side?
>
>
> I don’t really know, I’d need to have a short script which replicates it
> in order to identify the pattern exactly.
>
> if its pymysql, try another DBAPI. though this may be some artifact of
> the MySQL protocol.
>
> as always, if you’re doing anything with threads, concurrent use of a
> MySQL connection will usually lead to problems like this. but there can be
> other reasons too.
>
>
>
>
>
> Wesley
>
> 在 2014年3月27日星期四UTC+8下午8时58分40秒，Michael Bayer写道：
>>
>> when the DBAPI cursor has no .description object, it is determined to not
>> be a result-row returning object. The MySQLDB DBAPI has been observed to
>> occasionally have issues in this area, when a connection gets into a bad
>> state. There are likely patterns in how you’re calling it that lead it to
>> have this issue but you might try a different DBAPI like
>> mysql-connector-python just to see what’s different.
>>
>>
>>
>>
>> On Mar 27, 2014, at 7:41 AM, Ni Wesley <nis...@gmail.com> wrote:
>>
>> Hi all,
>> Today I get an error as title.
>> I use sqlalchemy + mysql.
>> Here is my code snippet:
>>
>> def dbquery(_table,whereclause):
>>
>> try:
>>
>> #_table=Table(tablename, metadata, autoload=True)
>>
>> #_table = tables[tablename]
>>
>> i=_table.select().where(whereclause)
>>
>> if direct_engine: #direct_engine is True
>>
>> res = engine.execute(i)
>>
>> return res
>>
>> else:
>>
>> session = scoped_session(sessionmaker(bind=engine))
>>
>> res = session.execute(i)
>>
>> return res
>>
>> session.close()
>>
>> except Exception,e:
>>
>> #dba_logger.log(40,'Exception when dbwriter:%s' % str(e))
>>
>> #dba_logger.log(20,'Exception detail:%s' % str(kwargs))
>>
>> exctrace('db','1','Error happened when querying
>> db',dba_logger,'Exception when dbquery:%s' % str(e),'Exception detail:%s' %
>> str(whereclause))
>>
>> #session.rollback()
>>
>> if not direct_engine:
>>
>> session.close()
>>
>> Here is snippet in another file involving dbquery:
>>
>> try:
>>
>> res = dbquery(tables[*'sessions_details'*],whereclause=and_(tables[
>> *'sessions_details'*].c.app_key==*self*.app_key,tables[
>> *'sessions_details'*].c.device_token==*self*._devicetoken))
>>
>> except Exception,e:
>>
>> exctrace(*'db'*,*'1'*,*'Error happened when querying
>> db'*,dba_logger,*'Exception
>> when query session_details:%s'* % str(e),*'Exception detail:appkey is
>> %s,devicetoken is %s'* % (*self*.app_key,*self*._devicetoken))
>>
>> *self*.read_message()
>>
>> return
>>
>> if res is None:
>>
>> logger.log(40,*'When query connection,mysql has gone or something,
>> just skip db and go-on'*)
>>
>> #here need to justify 0 or 1, later on
>>
>> *self*.status=*'0'*
>>
>> *self*.read_message()
>>
>> return
>>
>> if res.first() is None:
>>
>> if json_obj[*'action'*] == *'reg'*:
>>
>> So, the line in pink above raises the exception.
>>
>> Could anyone give some suggestion how this happened?
>>
>>
>> Thanks.
>>
>> Wesley
>>
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>>
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