python flask mysql using only one connection

Question

When I get over 100 concurrent requests, mysql.connect() produces a "too many connections" error. I'm using a managed database which doesn't give me a root user to increase the connection limit. Below is the temporary fix that I need to replace.

import flaskext.mysql

@app.route("/filter")
def filter_ep():

    # FIXME: hot fix for "too many connections" error
    conn = None
    errs = 0
    while not conn and errs < 100:
        try:
            conn = mysql.connect()
        except Exception as e:
            errs += 1
            time.sleep(0.001)

    cur = con.cursor()
    # pull `results` from database
    cur.close()
    conn.close()

    return results

When I tried doing the same code using a single global connection I got packet out of order errors suggesting that cursors are reading each others responses.

I think the correct solution is to make some sort of task queue for queries but not sure how to implement.

Answer 1

This is my current solution, It's still bad but at least it doesn't consume all available connections causing other things to break.

# FIXME: this is still bad
conn = None
errs = 0
# for 1s try to connect until there's an open conn in queue
while not conn and errs < 100:
    try: 
        conn = mysql.connector.connect(pool_name="ropool", pool_size=4, **db.mysql_connection_args)
    except Exception as e:
        errs += 1
        time.sleep(0.01)
if not conn:
    return json.dumps({"errorMessage" : "failed to connect to database"}), 500