Well it is possible QueuePool doesn't do the right thing under eventlet,
though we use it a lot w/ eventlet in Openstack and I've tested it
myself quite a bit. Have not peeked at this number, however.
You'd need to produce for me a self contained test suite that
illustrates this behavior occurring, that would be very helpful in order
to track this down.
Do you see too many actual database connections in play when this
condition occurs ? That is, using netstat you'd see more than 120
connections.
On 06/27/2016 11:30 AM, 'Dave Puffin' via sqlalchemy wrote:
Thanks for the reply :)
I think you're right in that it must be threading related somehow, but
it looks like all the monkeypatching has been applied correctly. If I
examine the locking object used in the pool I get:
type(engine.pool._overflow_lock)
<class 'eventlet.semaphore.Semaphore'>
On Mon, Jun 27, 2016 at 4:21 PM, Mike Bayer <mike...@zzzcomputing.com
<mailto:mike...@zzzcomputing.com>> wrote:
On 06/27/2016 10:48 AM, davepuffin via sqlalchemy wrote:
Hi
QueuePool.status() is returning some odd looking negative values
from
one of our production applications.
engine.pool.status()
'Pool size: 20 Connections in pool: 19 Current Overflow: -36 Current
Checked out connections: -35'
The pool was initialised with: pool_size=20, max_overflow=100.
Does anyone know of any scenarios that could cause this?
We are using SQLAlchemy==1.0.13 connecting to MySql 5.6.
The application runs in a single python process that uses
eventlet to
manage many greenthreads.
well that's very likely to be related, are you monkeypatching all
thread / Lock primitives before importing SQLAlchemy? QueuePool
relies upon traditional thread and locking primitives which will
fail if you use them unpatched in a green-thread situation. The
Queue here is basically Python's Queue.Queue so it appears like the
queue has been populated with more objects than it is supposed to allow.
The situation appears to occur sometime after the overflow has
been used.
Thanks
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