uwsgi_gevent_pyodbc

Repository to show the uWSGI + gevent + pyodbc delay issue.

This test case is made of a Flask application that simply calls asynchronously a SLEEP 5 inside a MSSQL database. We expect the response to be returned directly, without waiting for the MSSQL return.

• If we run the application with uWSGI, gevent and pyodbc, we can observe that uWSGI waits for the greenlet before returning
• If we replace pyodbc with pymssql, the request is returned directly
• In any case, if we run the same application without uWSGI, the request is returned directly

Versions in use: python 3.6, uWSGI 2.0.17.1, gevent 1.2.1

---

Requirements

• docker-compose (Running with 1.21.2)

How to test

cd /path/to/uwsgi_event_pyodbc
docker-compose up
docker exec -it container_name bash
cd /app

python run.py #running without uwsgi
uwsgi uwsgi.ini #running with uwsgi

Then, using CURL/POSTMAN

# execute using pyodbc
curl http://0.0.0.0:8082/gevent/pyodbc

# execute using pyodbc with a sleep
curl http://0.0.0.0:8082/gevent/pyodbc/sleep

# execute using pymssql
curl http://0.0.0.0:8082/gevent/pymssql

RESPONSE USING uwsgi:

curl http://0.0.0.0:8082/gevent/pyodbc

Api's log:

---- START EXEC ASYNC
-----RETURNING
...finish ASYNC FUNCTION :)
[pid: 339|app: 0|req: 4/4] 172.24.0.1 () {28 vars in 319 bytes} [Thu Oct 25 13:16:18 2018] GET /gevent/pyodbc => generated 3 bytes in 5064 msecs (HTTP/1.1 200) 2 headers in 70 bytes (4 switches on core 99)


curl http://0.0.0.0:8082/gevent/pyodbc/sleep

Api's log:

---- START EXEC ASYNC
-----RETURNING
[pid: 339|app: 0|req: 5/5] 172.24.0.1 () {28 vars in 331 bytes} [Thu Oct 25 13:17:05 2018] GET /gevent/pyodbc/sleep => generated 3 bytes in 1 msecs (HTTP/1.1 200) 2 headers in 70 bytes (4 switches on core 99)
...finish ASYNC FUNCTION :)



curl http://0.0.0.0:8082/gevent/pymssql

Api's log:

---- START EXEC ASYNC
-----RETURNING
[pid: 339|app: 0|req: 6/6] 172.24.0.1 () {28 vars in 320 bytes} [Thu Oct 25 13:17:39 2018] GET /gevent/pymssql => generated 3 bytes in 7 msecs (HTTP/1.1 200) 2 headers in 70 bytes (4 switches on core 99)
...finish ASYNC FUNCTION :)