Python实现数据库并行读取和写入实例

max_process = 16 #最大进程数

def read_SQL_write(r_host,r_port,r_user,r_passwd,r_db,r_charset,w_host,w_port,w_user,w_passwd,w_db,w_charset,cmd,index=None):
  #得到tem字典保存着信息
  try:
    conn = pymysql.Connect(host=r_host, port=r_port, user=r_user, passwd =r_passwd, db =r_db, charset =r_charset)
    cursor = conn.cursor()
    cursor.execute(cmd)
  except Exception as e:
    error = "[-][-]%d fail to connect SQL for reading" % index
    log_error('error.log',error)
    return 
  else:
    tem = cursor.fetchone()
    print('[+][+]%d succeed to connect SQL for reading' % index)
  finally:
    cursor.close()
    conn.close()
  
  try:
    conn = pymysql.Connect(host=w_host, port=w_port, user=w_user, passwd =w_passwd, db =w_db, charset =w_charset)
    cursor = conn.cursor()
    cursor.execute(cmd)
  except Exception as e:
    error = "[-][-]%d fail to connect SQL for writing" % index
    log_error('error.log',error)
    return 
  else:
    print('[+][+]%d succeed to connect SQL for writing' % index)
  
  
  r_dict = dict()
  r_dict['id'] = tem[0]
  r_dict['content_id'] = tem[1]
  r_dict['pub_date'] = tem[2]
  r_dict['title'] = cht_to_chs(tem[3])
  r_dict['title_score'] =tem[4]![](http://images2015.cnblogs.com/blog/1172464/201706/1172464-20170609000900309-1810357590.png)

  r_dict['news_content'] = cht_to_chs(tem[5])
  r_dict['content_score'] = tem[6]
  
  for key in stock_dict.keys():
    #能找到对应的股票
    if stock_dict[key][1] and ( r_dict['title'].find(stock_dict[key][1])!=-1 or r_dict['news_content'].find(stock_dict[key][1])!=-1 ):
      w_dict=dict()
      w_dict['code'] = key
      w_dict['english_name'] = stock_dict[key][0]
      w_dict['cn_name'] = stock_dict[key][1]
      #得到分数
      if r_dict['title_score']:
        w_dict['score']=r_dict['title_score']
      else:
        w_dict['score']=r_dict['content_score']
      
      #开始写入
      try:
        global max_process
        cmd = "INSERT INTO dyx_stock_score%d VALUES ('%s', '%s' , %d , '%s' , '%s' , %.2f );" % \
          (index%max_process ,r_dict['content_id'] ,r_dict['pub_date'] ,w_dict['code'] ,w_dict['english_name'] ,w_dict['cn_name'] ,w_dict['score'])
        cursor.execute(cmd)
        conn.commit()
      except Exception as e:
        error = "  [-]%d fail to write to SQL" % index
        cursor.rollback()
        log_error('error.log',error)
      else:
        print("  [+]%d succeed to write to SQL" % index)

  cursor.close()
  conn.close()
def main():
  num = 238143#数据库查询拿到的总数
  p = None
  for index in range(1,num+1):
    if index%max_process==1:
      if p:
        p.close()
        p.join()
      p = multiprocessing.Pool(max_process)
    r_cmd = ('select id,content_id,pub_date,title,title_score,news_content,content_score from dyx_emotion_analysis where id = %d;' % (index))
    p.apply_async(func = read_SQL_write,args=(r_host,r_port,r_user,r_passwd,r_db,r_charset,w_host,w_port,w_user,w_passwd,w_db,w_charset,r_cmd,index,))

  if p:
    p.close()
    p.join()