Hi
I was playing with multiple mysql connection in separate processes
with the multiprocessing module.
When I run the following code in linux all goes well. But when I try
in win32 I get a pickle error saying it cant pickle None Type when I
start the process.
Python 2.6 on both platforms.
Thanks in advance.
from __future__ import print_function
import sys
import os
import platform
import MySQLdb
import multiprocessing
import time
import cPickle as Pickle
VERBOSE = False
class SQL_Query(object):
def __init__(self, SQL, callback):
self.SQL = SQL
self.callback = callback
class Connection(multiprocessing.Process):
def __init__(self,in_queue, out_queue):
multiprocessing.Process.__init__(self)
self.in_queue = in_queue
self.out_queue = out_queue
self.counter = 10 #int(self.conf["db_num_queries"]) # Number of
queries to handle before closing down.
self.all_ok = True
self.con = self.get_connection()
def escape(self, string):
return MySQLdb.escape(string)
def execute(self, sql):
"Return results of sql from database, sql must be valid SQL as
no
checking is done."
if VERBOSE:
print (sql)
res = True
last_id = 0
self.counter -= 1
if self.con:
try:
cur = self.con.cursor()
cur.execute("START TRANSACTION")
cur.execute(sql)
res = cur.fetchall()
self.con.commit()
last_id = cur.execute("SELECT LAST_INSERT_ID()")
cur.close()
except Exception as e :
res = False # For tracking insert failure
etc...
self.all_ok = False
self.con.rollback()
self.out_queue.put((res, last_id))
else:
util.error_ui(message = "A Connection has not been
established with
the database.")
def get_connection(self):
self.con = ""
hst = "127.0.0.1"
usr = "usr"
pwd = "pass"
database = "db"
try:
self.con = MySQLdb.connect(host=hst, user=usr,
passwd=pwd, db=database)
except Exception as e:
pass
return self.con
def run(self):
proc_name = self.name
while self.counter > 0:
next_sql = self.in_queue.get()
print(self, self.counter, next_sql.SQL)
if next_sql is None:
# Stop Process
return
result = self.execute(next_sql.SQL)
self.out_queue.put(result)
self.close_down()
self.out_queue.put(("RESTART", self.name))
return
#
# clean up
#
def close_down(self, arg1 = None):
if self.con:
self.con.close()
if __name__ == "__main__":
in_queue = multiprocessing.Queue()
out_queue = multiprocessing.Queue()
pool = []
pool.append(Connection(in_queue, out_queue))
pool.append(Connection(in_queue, out_queue))
pool.append(Connection(in_queue, out_queue))
print(pool)
for c in pool:
c.start()
for i in range(100):
print(i)
s = SQL_Query("SELECT * FROM customer ", "-")
#time.sleep(0.015)
in_queue.put(s)
while True:
o = out_queue.get()
if o:
if o[0]=="RESTART":
print(o)
print(pool)
for c in pool:
if c.name == o[1]:
print(c)
c.join()
c.terminate()
pool.remove(c)
nc = Connection(in_queue,
out_queue)
nc.start()
pool.append(nc)
--
--
Rob
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