Plus, if it's any help. the *does* seem resolve itself after ~2 hours. That, or it can be side-stepped by sending a SIGINT signal (ctrl-c) to the flask app when it is hung. the SIGINT seems to kill the 15th (hung) request and allows the app to continue processing other requests successfully.
On Saturday, December 28, 2019 at 10:12:13 PM UTC-6, Brian Paterni wrote: > > Hi, > > I seemingly have a problem with flask/socketio/eventlet/sqlalchemy + MSSQL > when >= 15 parallel requests have been made. I've built a test app: > > https://github.com/bpaterni/flask-app-simple-blocking-eventlet > > that can be used to reproduce the problem. It will hang if >= 15 parallel > request have been made to the '/api/busy/mssql' endpoint. > > I'm not sure if the root cause of the problem is based in the SQL Server > ODBC Driver, sqlalchemy, or eventlet, but I've already paid the microsoft > support tax only to be told that there's insufficient evidence to indicate > the ODBC driver is at fault. So I thought I would post the issue here to > see if anybody would be able to help in pinpointing the code that is at > fault with this problem. > > Once the test app above is running and has a valid SQL server to query, > you should be able to reproduce the hang with > > seq 15 | parallel -j0 "curl -s localhost:5000/api/busy/mssql && echo {}" > > The hang seems lo occur consistently on the 15th request. This happens > even when connection pool_size/max_overflow are adjusted away from their > respective default values which leads me to believe that exhausting the > connection pool is not the cause of the problem. Though there may be some > other reason behind the scenes for the hang occurring at the 15th > connection(?) > > Thanks very much for any help that can be provided in resolving this issue! > :) > -- 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/36aa8c3b-d960-4238-bc83-4d33ed325435%40googlegroups.com.
