python 采用 BoundedSemaphore 限制多进程访问qps-白红宇

                         
# -*- coding: utf-8 -*-
"""
Created on Tue Sep 19 00:06:12 2017
@author: 37652
"""
import
threading
import
time
import
timer2
import
requests
def
showfun(n):
    
requests.get(
"http://test.com/"
)
    
print
"here\n"
    
def
release():
    
print
"%s begin start release =============== \n"
%
(time.ctime())
    
# 增加之前 先清除之前遗留的 避免出现遗留计数器影响下一秒qps
    
while
semlock.acquire(blocking
=
0
):
            
pass
        
# 增加计数器
    
for
i 
in
range
(
20
):
        
try
:
            
semlock.release()
        
except
Exception, e:
                
# 出现异常 进行推出 理想状态是出现计数器自增超过配额
                
# TODO 未对异常进行细分 
            
print
"\n======"
,e
            
break
    
print
"%s end start release =============== \n"
%
(time.ctime())
if
__name__ 
=
=
'__main__'
:
    
maxconnections 
=
20
# 计数器最大值
    
semlock 
=
threading.BoundedSemaphore(maxconnections)
    
    
reThread 
=
timer2.apply_interval(
1000
, release) 
# 每秒钟进行一次计数器释放
    
    
list
=
[]
    
i 
=
0
    
while
True
:
        
semlock.acquire()
        
i
+
=
1
        
t
=
threading.Thread(target
=
showfun, args
=
(i,))
        
list
.append(t)
        
t.start()
        
if
time.time() > 
1505754200
:   
# 测试结束时间戳
            
break
        
    
for
j 
in
list
:
        
j.join()
    
reThread.cancel()
        
      

注： python threading 模块内有两个计数器同步原语

Semaphore 无上限

BoundedSemaphore 初始设置最大值如果release调用超过最大值则出ValueError

本文转自拖鞋崽 51CTO博客，原文链接:http://blog.51cto.com/1992mrwang/1966522