On Monday, December 30, 2019 at 9:07:45 AM UTC-6, Mike Bayer wrote: > > > On Sun, Dec 29, 2019, at 11:54 PM, Brian Paterni wrote: > > On Sunday, December 29, 2019 at 1:17:24 AM UTC-6, Mike Bayer wrote: > > > I can't run the test app however 15 seems like your connection pool is set > up at its default size of 5 connections + 10 overflow, all connections are > being checked out, and none are being returned. > > > Hm, is the issue with running the app possibly something I could help with? > > > sure, if you can turn it into a single file, runnable MCVE with zero > depedendencies other than SQLAlchemy, a single MSSQL Python driver (please > note that MS's ODBC driver, while necessary, is not a Python driver by > itself), and in this case eventlet, I can run that. However I think > you likely should be able to reproduce your issue not using SQLAlchemy at > all and simply using pyodbc directly assuming that's the driver you are > using. > > > http://stackoverflow.com/help/mcve > > I've created: https://github.com/bpaterni/simple-blocking-eventlet
Which should be a stripped down version of the flask-app I'd posted before. You are correct in that the problem persists when using only pyodbc, and as a result I've gone ahead and created an issue with that project in order to try and get at the source of this problem: https://github.com/mkleehammer/pyodbc/issues/694 > > Apparently it *does* (or should) support async, as it is mentioned several > times in the RELEASE_NOTES shipped with the driver. I'm not sure if it's > does so implicitly or explicitly though. > > > unfortunately things are not that simple. PostgreSQL for example > supports a non-blocking API. However, you can't just use psycopg2 out of > the box and expect it to work, psycopg2 offers an explicit API for this > that has to be adapted, which you can see here: > http://initd.org/psycopg/docs/advanced.html#green-support in order for > that API to work with eventlet, you need to use a special eventlet > adaptation form here: https://pypi.org/project/psycogreen/ > > I believe psycogreen (or it's intended behavior) has already been integrated into eventlet: https://github.com/eventlet/eventlet/blob/master/eventlet/support/psycopg2_patcher.py which is probably the reason postgresql has been implicitly working as expected this whole time. I agree that some additional hoops may need to be jumped in order for MSSQL to work as expected, but this hang on >= 15 busy connections is strange. Hopefully it is something that can be bandaid'ed in pyodbc until some kind of genuine async interface can be added to the project... -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/e5d47afa-dbfa-4d99-b5e9-47fe6ab0690f%40googlegroups.com.
