Create DB connection and maintain on multiple processes (multiprocessing)

Try to isolate the creation of your connection in the Consumer constructor, then give it to the executed Task :

import multiprocessing, time, psycopg2class Consumer(multiprocessing.Process):    def __init__(self, task_queue, result_queue):        multiprocessing.Process.__init__(self)        self.task_queue = task_queue        self.result_queue = result_queue        self.pyConn = psycopg2.connect("dbname='geobase_1' host = 'localhost'")        self.pyConn.set_isolation_level(0)    def run(self):        proc_name = self.name        while True:            next_task = self.task_queue.get()            if next_task is None:                print 'Tasks Complete'                self.task_queue.task_done()                break                        answer = next_task(connection=self.pyConn)            self.task_queue.task_done()            self.result_queue.put(answer)        returnclass Task(object):    def __init__(self, a):        self.a = a    def __call__(self, connection=None):                pyConn = connection        pyCursor1 = pyConn.cursor()        procQuery = 'UPDATE city SET gid_fkey = gid FROM country  WHERE ST_within((SELECT the_geom FROM city WHERE city_id = %s), country.the_geom) AND city_id = %s' % (self.a, self.a)        pyCursor1.execute(procQuery)        print 'What is self?'        print self.a        return self.a    def __str__(self):        return 'ARC'    def run(self):        print 'IN'