python Multithreaded Test Concurrency Method for post Request Server

As follows:

# -*- coding: utf-8 -*-
import requests
import threading
import time
class postrequests():
 def __init__(self):
  self.url = ' Request web address '
  self.files = {
 'unknown_image':open(' LIU Shi-shi .jpg','rb')
}
 def post(self):
  try:
   r = requests.post(self.url,files=self.files)
   print(r.text)
  except Exception as e:
   print(e)

def login():
 login = postrequests()
 return login.post()
# if __name__ == '__main__':
#  login()
try:
 i = 0
 #  Number of open threads 
 tasks_number = 150
 print(' Test Start ')
 time1 = time.clock()
 while i < tasks_number:
  t = threading.Thread(target=login)
  t.start()
  i +=1
 time2 = time.clock()
 times = time2 - time1
 print(times/tasks_number)
except Exception as e:
 print(e)