python - when I try to run the code, it get the error:PicklingError: Can't pickle <type 'function'>: attribute lookup __builtin__.function failed -

what wrong code? thank

import os import os.path import time global item_count #-*- coding: cp936 -*- import mysqldb import mysqldb.cursors import threading import multiprocessing time import sleep,ctime   def qucun():      #connect mysql     conn=mysqldb.connect(host="localhost",user="root",passwd="caihong")     cursor=conn.cursor()     try:         cursor.execute("""create database if not exists quad""")     except:         print 'quad exist'       conn.select_db('quad')     conn=mysqldb.connect(host="localhost",user="root",passwd="caihong",db="quad")     #get cursor     cursor=conn.cursor()      try:         cursor.execute("""create table if not exists record(fn1 varchar(100),         fn2 varchar(100),fn3 varchar(100),fn4 varchar(100),         fn5 varchar(100),fn6 varchar(100),fn7 varchar(100),fn8 varchar(100))""")     except:         print 'table record exist'      loops=['2013071818_1.txt','2013071818_2.txt','2013071818_3.txt','2013071818_4.txt','2013071818_5.txt']         def loop(nloop,filename):           print 'this loop%s start at:'%nloop,ctime()         #connect quad         conn=mysqldb.connect(host="localhost",user="root",passwd="caihong",db="quad")         conn.select_db('quad')         #get cursor         cursor=conn.cursor()          newitem=open('c:\\python27\\caihong\\%s'%filename,'r')         data=[line.strip() line in newitem.readlines()]         print data         ##put data value         values=['%s'%data[0],'%s'%data[1],'%s'%data[2],'%s'%data[3],'%s'%data[4],                 '%s'%data[5],'%s'%data[6],'%s'%data[7]]          cursor.execute("""insert record values(%s,%s,%s,%s,%s,%s,%s,%s)""",values);             conn.commit()         cursor.close()         sleep(2)         print 'this loop done at',ctime()        if __name__=='__main__':          print 'starting at:',ctime()         threads=[]         nloops=range(len(loops))         pool=multiprocessing.pool(processes=2)         in nloops:             t=pool.apply_async(loop,(i,loops[i]))           pool.close()         pool.join()          if t.successful():             print 'successful'             print 'all done at:',ctime()         os.system("pause")  qucun() 

1. you attempting call locally defined function in async.
2. you trying share open connection between processes.

first tricky implement in 2.7 , second impossible in multiprocessing

you have use separate connection each process in process pool.

import os import os.path import time global item_count #-*- coding: cp936 -*- import mysqldb import mysqldb.cursors import threading import multiprocessing time import sleep,ctime  connection = none  def close_connection():     connection.close()  def get_connection():     global connection      #if process pool member launched first time - create connection     if connection none:          conn = mysqldb.connect( host="localhost",                                 user="root",                                 passwd="caihong")         cursor = conn.cursor()         try:             cursor.execute("""create database if not exists quad""")         except:             print 'quad exist'          conn.select_db('quad')          connection = mysqldb.connect(host="localhost",                                      user="root",                                      passwd="caihong",                                      db="quad")          cursor = connection.cursor()          try:             cursor.execute("""create table if not exists record(fn1 varchar(100),             fn2 varchar(100),fn3 varchar(100),fn4 varchar(100),             fn5 varchar(100),fn6 varchar(100),fn7 varchar(100),fn8 varchar(100))""")         except:             print 'table record exist'          # dont need close connection after each insert.         # insted - register finalizer once         # called right before pool.close()         multiprocessing.util.finalize(connection, close_connection, exitpriority=1)      #use existing connection     return connection  def loop(nloop, filename):     conn = get_connection()     cursor = conn.cursor()      print 'this loop %s start at: %s'%(nloop, ctime())     open('c:\\python27\\caihong\\%s'%filename, 'r') newitem:         data = [line.strip() line in newitem.readlines()]          # values=['%s'%data[0],'%s'%data[1],'%s'%data[2],'%s'%data[3],'%s'%data[4],         #         '%s'%data[5],'%s'%data[6],'%s'%data[7]]         # ^^^ thats bad way stringify list          cursor.execute('insert record values(%s)', ','.join(data));      conn.commit()      # dont need close connection after each insert.      # cursor.close()     print 'this loop done at', ctime()   loops = ['2013071818_1.txt', '2013071818_2.txt', '2013071818_3.txt', '2013071818_4.txt', '2013071818_5.txt']  if __name__=='__main__':     pool = multiprocessing.pool(processes=2)     results = []     i, loopfile in enumerate(loops):         results.apply(pool.apply_async(loop, (i, loopfile)))      pool.close()     pool.join()      if all((res.successful() res in results)):         print 'successful'      print 'all done at:', ctime()         os.system('pause')