green_pool.py

import eventlet

pool = eventlet.GreenPool(size=2)

def printer(x):
    print x
    
print "execute 1"
pool.spawn(printer, 1)
print "execute 2"
pool.spawn(printer, 2)
print "execute 3"
pool.spawn(printer, 3)
print "execute 4"
pool.spawn(printer, 4)

pool.waitall()