zzzeek/eventlet_pymysql.py

## eventlet_pymysql.py
import random
import time as blocking_time

import eventlet
import pymysql

# monkeypatch Python network libraries so that they are non blocking. all
# Python code that uses the pure Python network IO functions will be non
# blocking, where all  IO waiting will defer back to eventlet where it will
# pass off work to another greenlet.
eventlet.monkey_patch(socket=True)


def connect():
    """Connect to a local MySQL database.

    No hostname is given, so this uses a UNIX socket.  Any kind of socket
    will do.

    """

    return pymysql.connect()


def do_work(greenlet, cpu_blocking):
    while True:
        print(
            "greenlet %s CPU blocking for %.4f sec" % (greenlet, cpu_blocking)
        )
        blocking_time.sleep(cpu_blocking)
        conn = connect()
        print("greenlet %s connected to the database" % greenlet)


def retreive_connection_timeout():
    """Get the configured connect_timeout from the server.

    This is usually ten seconds.  If it's much higher, then this script
    will take a lot longer to illustrate the effect.

    """
    conn = connect()
    cursor = conn.cursor()
    cursor.execute("show variables like 'connect_timeout'")
    connect_timeout = int(cursor.fetchone()[1])
    cursor.close()
    conn.close()
    return connect_timeout


connect_timeout = retreive_connection_timeout()

pool = eventlet.GreenPool()

print(
    "Creating ten continuous greenlets with a tiny amount of CPU work in "
    "between database connections"
)
for i in range(10):
    pool.spawn_n(do_work, i, random.choice([0.001, 0.002, 0.005]))
eventlet.sleep(1)
print(
    "Now adding a CPU expensive worker that will wait "
    "longer than %d seconds to finish its CPU work" % connect_timeout
)
pool.spawn_n(do_work, i, connect_timeout + 2)
pool.waitall()
	import random
	import time as blocking_time

	import eventlet
	import pymysql

	# monkeypatch Python network libraries so that they are non blocking. all
	# Python code that uses the pure Python network IO functions will be non
	# blocking, where all IO waiting will defer back to eventlet where it will
	# pass off work to another greenlet.
	eventlet.monkey_patch(socket=True)


	def connect():
	"""Connect to a local MySQL database.

	No hostname is given, so this uses a UNIX socket. Any kind of socket
	will do.

	"""

	return pymysql.connect()


	def do_work(greenlet, cpu_blocking):
	while True:
	print(
	"greenlet %s CPU blocking for %.4f sec" % (greenlet, cpu_blocking)
	)
	blocking_time.sleep(cpu_blocking)
	conn = connect()
	print("greenlet %s connected to the database" % greenlet)


	def retreive_connection_timeout():
	"""Get the configured connect_timeout from the server.

	This is usually ten seconds. If it's much higher, then this script
	will take a lot longer to illustrate the effect.

	"""
	conn = connect()
	cursor = conn.cursor()
	cursor.execute("show variables like 'connect_timeout'")
	connect_timeout = int(cursor.fetchone()[1])
	cursor.close()
	conn.close()
	return connect_timeout


	connect_timeout = retreive_connection_timeout()

	pool = eventlet.GreenPool()

	print(
	"Creating ten continuous greenlets with a tiny amount of CPU work in "
	"between database connections"
	)
	for i in range(10):
	pool.spawn_n(do_work, i, random.choice([0.001, 0.002, 0.005]))
	eventlet.sleep(1)
	print(
	"Now adding a CPU expensive worker that will wait "
	"longer than %d seconds to finish its CPU work" % connect_timeout
	)
	pool.spawn_n(do_work, i, connect_timeout + 2)
	pool.waitall()