Hi,

I know this problem shows on group from time to time, but suggested
solutions does not work for me (pool_recycle). Here is my situation:

1. I am using SQLAlchemy 0.4.7p1-2 from Pylons 0.9.6.2-2 on Debian
Lenny (xen-amd64)
2. From time to time I see in logs: "MySQL has gone away" and this is
reason why some of HTTP requests made to my Pylons app fail.
3. My settings in configuration file are as follows:

>>>
...
sqlalchemy.url = mysql://USER:p...@host:3306/DBNAME?charset=utf8
sqlalchemy.pool_recycle = 60 #(wait_timeout on MySQL side is default,
which is 8 hours AFAIK)
sqlalchemy.convert_unicode = True
...
<<<

4. I have logging enabled, and here is what I see when request fail
(please look at connection identified as "at 2238cd0", its lifetime is
one minute but it looks that in very last moment (the same second
which it should be destroyed) this connection is returned from pool,
possibly because of some http request - unfortunately after that we
can see that error occurs). Also what is surprise for me why is whole
pool recreating after this?

P.S. Third column is thread id.

>>>
16:19:07,621 INFO  1115703632 [sqlalchemy.pool.QueuePool.0x..10]
Closing connection <_mysql.connection open to 'DB_HOST' at 2262480>
16:19:07,624 INFO  1115703632 [sqlalchemy.pool.QueuePool.0x..10]
Created new connection <_mysql.connection open to 'DB_HOST' at
2238cd0>
16:19:07,624 INFO  1115703632 [sqlalchemy.pool.QueuePool.0x..10]
Connection <_mysql.connection open to 'DB_HOST' at 2238cd0> checked
out from pool
16:19:07,740 INFO  1115703632 [sqlalchemy.pool.QueuePool.0x..10]
Connection <_mysql.connection open to 'DB_HOST' at 2238cd0> being
returned to pool
16:20:02,291 INFO  1107310928 [sqlalchemy.pool.QueuePool.0x..10]
Connection <_mysql.connection open to 'DB_HOST' at 2364540> checked
out from pool
16:20:02,413 INFO  1107310928 [sqlalchemy.pool.QueuePool.0x..10]
Connection <_mysql.connection open to 'DB_HOST' at 2364540> being
returned to pool
16:20:03,477 INFO  1132489040 [sqlalchemy.pool.QueuePool.0x..10]
Connection <_mysql.connection open to 'DB_HOST' at 222afb0> checked
out from pool
16:20:03,516 INFO  1132489040 [sqlalchemy.pool.QueuePool.0x..10]
Connection <_mysql.connection open to 'DB_HOST' at 222afb0> being
returned to pool
16:20:07,573 INFO  1124096336 [sqlalchemy.pool.QueuePool.0x..10]
Connection <_mysql.connection open to 'DB_HOST' at 2238cd0> checked
out from pool
16:20:07,574 INFO  1124096336 [sqlalchemy.pool.QueuePool.0x..10]
Invalidate connection <_mysql.connection open to 'DB_HOST' at 2238cd0>
(reason: OperationalError:(2006, 'MySQL server has gone away'))
16:20:07,574 INFO  1124096336 [sqlalchemy.pool.QueuePool.0x..10]
Closing connection <_mysql.connection open to 'DB_HOST' at 2238cd0>
16:20:07,574 INFO  1124096336 [sqlalchemy.pool.QueuePool.0x..10]
Connection None being returned to pool
16:20:07,575 INFO  1124096336 [sqlalchemy.pool.QueuePool.0x..10]
Closing connection <_mysql.connection open to 'DB_HOST' at 2364540>
16:20:07,575 INFO  1124096336 [sqlalchemy.pool.QueuePool.0x..10]
Closing connection <_mysql.connection open to 'DB_HOST' at 222afb0>
16:20:07,575 INFO  1124096336 [sqlalchemy.pool.QueuePool.0x..10] Pool
disposed. Pool size: 5  Connections in pool: 0 Current Overflow: -5
Current Checked out connections: 0
16:20:07,575 INFO  1124096336 [sqlalchemy.pool.QueuePool.0x..10] Pool recreating
<<<

Any ideas?

Thanks for your help!

Cheers,
--
Kamil Gorlo

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