On Wed, Aug 24, 2011 at 9:49 PM, Michael Bayer <[email protected]> wrote:
>
> On Aug 23, 2011, at 11:21 PM, limodou wrote:
>
>> On Sat, Oct 23, 2010 at 9:22 PM, Michael Bayer <[email protected]>
>> wrote:
>>>
>>> pool recycle means a connnection that is 3600 seconds old will be thrown
>>> away. does not help with reconnects.
>>>
>>> When a "server gone away" error is detected, the entire connection pool is
>>> thrown away and rebuilt. So assuming one engine, you'd get this error once
>>> for each connection that is still checked out and attempts a new operation.
>>> Subsequent transactions will proceed since the pool has been rebuilt.
>>>
>>> There was also a Mysql-reconnect bug fixed in 0.6.3 where previous versions
>>> might have impacted this.
>>>
>>
>> I want to know if this means that the first transaction will still be
>> failed, and others will be successful?
>
> When the error is received, whatever transactional state has occurred on that
> connection is gone - however, if you're getting this error on the very first
> moment the connection is used, there's no state on the connection in any case.
>
>
>> And sqlalchemy can automatically rebuild at the time the error occured
>> but not the next time?
>
> Not sure what the question is here. You can call engine.dispose() at any
> time to rebuild the connection pool completely, if you were building an
> approach to "ping" the connection ahead of time perhaps.
>
>
finally I found the problem. In my case I build my own ORM based on
sqlalchemy, I call it "uliorm". And it only use base select, update,
insert, delete statements. And in order to keep the whole process can
share the same connection object, I used the
engin.contextual_connect() to get the default connection, and my logic
same like this:
db = create_engine(xxx, pool_recycle=7200)
conn = db.contextual_connect()
db.begin()
try:
try:
db.execute(yyyy)
db.commit()
except:
db.rollback()
finally:
conn.close()
But it seems that the conn is not close correctly, so the pool will
not recycle it.
And I changed my underliying connection process code, I built the
connection object in a Begin() function, and stored it to a
threading.local() object. And I also provide Commit() and Rollback()
functions. So I gave up the contextual_connect(). And the result seems
right now.
--
I like python!
UliPad <<The Python Editor>>: http://code.google.com/p/ulipad/
UliWeb <<simple web framework>>: http://code.google.com/p/uliweb/
My Blog: http://hi.baidu.com/limodou
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