test to see if psycogreen is necessary to run sqlalchemy + gevent + psycopg2 concurrently

readme.md

This is a test to see if psycogreen is necessary to run sqlalchemy + gevent + psycopg2 concurrently.

benchmark command (concurrency of 10)

ab -n 10 -c 10 127.0.0.1:8080/wait

psychopg2 - sync worker (expecting concurrency of 2)

gunicorn -b 127.0.0.1:8080 -w 2 test:app

Requests per second: 1.99 [#/sec] (mean)

psychopg2 - gevent worker - test_no_psycogreen.py (expecting concurrency of 10)

gunicorn -b 127.0.0.1:8080 -w 2 test:app -k gevent

Requests per second: 1.98 [#/sec] (mean)

psychopg2 - gevent worker - test_psycogreen.py (expecting concurrency of 10)

gunicorn -b 127.0.0.1:8080 -w 2 test:app -k gevent

Requests per second: 9.42 [#/sec] (mean)

Results

Yes, psycogreen is required.

requirements.txt

Flask
Flask-SQLAlchemy
gunicorn
gevent
psycopg2
sqlalchemy
psycogreen

test_no_psycogreen.py

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgres://localhost/postgres'
db = SQLAlchemy(app)


@app.route("/wait")
def wait():
    db.session.execute('select pg_sleep(1.0)')
    return "ok"

test_psycogreen.py

from psycogreen.gevent import patch_psycopg
patch_psycopg()  # the only change

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgres://localhost/postgres'
db = SQLAlchemy(app)


@app.route("/wait")
def wait():
    db.session.execute('select pg_sleep(1.0)')
    return "ok"