发布于 2014-12-01 19:16:12 | 1971 次阅读 | 评论: 1 | 来源: 网友投递

这里有新鲜出炉的Python教程,程序狗速度看过来!

Python编程语言

Python 是一种面向对象、解释型计算机程序设计语言,由Guido van Rossum于1989年底发明,第一个公开发行版发行于1991年。Python语法简洁而清晰,具有丰富和强大的类库。它常被昵称为胶水语言,它能够把用其他语言制作的各种模块(尤其是C/C++)很轻松地联结在一起。


本文为大家讲解的是Python提示[Errno 32]Broken pipe导致线程crash错误解决方法,是ThreadingHTTPServer实现http服务中经常会遇到的问题,需要的朋友可以参考下

1. 错误现象
ThreadingHTTPServer 实现的 http 服务,如果客户端在服务器返回前,主动断开连接,则服务器端会报 [Errno 32] Broken pipe 错,并导致处理线程 crash.
下面先看个例子,python 版本: 2.7
示例代码

#!/usr/bin/env python
#!coding=utf-8
 
import os
import time
import socket
import threading
from BaseHTTPServer import HTTPServer ,BaseHTTPRequestHandler
from SocketServer import ThreadingMixIn
 
class RequestHandler(BaseHTTPRequestHandler):
    def do_GET(self):
        """
        处理get请求
        """      
        query=self.path
        print "query: %s thread=%s" % (query, str(threading.current_thread()))
        
        #ret_str="<html>" + self.path + "<br>" + str(self.server) + "<br>" + str(self.responses) +  "</html>"
        ret_str="<html>" + self.path + "<br>" + str(self.server) +  "</html>"
        
        time.sleep(5)
        
        try:
            self.send_response(200)
            self.send_header('Content-type','text/html')
            self.end_headers()
            self.wfile.write(ret_str)
        except socket.error, e:
            print "socket.error : Connection broke. Aborting" + str(e)
            self.wfile._sock.close()  # close socket
            self.wfile._sock=None
            return False
       
        print "success prod query :%s" % (query)
        return True
 
#多线程处理
class ThreadingHTTPServer(ThreadingMixIn,HTTPServer):
    pass
    
if __name__ == '__main__':
    serveraddr = ('',9001)
 
    ser = ThreadingHTTPServer(serveraddr,RequestHandler)
    ser.serve_forever()
    sys.exit(0)


运行服务
./thread_http_server_error.py
第1次 curl ,等待返回

[~]$curl -s 'http://10.232.41.142:9001/hello1′
<html>/hello1<br><__main__.ThreadingHTTPServer instance at 0x37483b0></html>[~]$
此时服务器端输出日志如下:
$./thread_http_server_error.py
query: /hello1 thread=
search041142.sqa.cm4.tbsite.net – - [15/May/2014 15:02:27] “GET /hello1 HTTP/1.1″ 200 -
success prod query :/hello1


第2次 curl ,不等待返回,ctrl +C 来模拟客户端断开

[~]$curl -s 'http://10.232.41.142:9001/hello2′
[~]$ ctrl+C


此时服务器端输出日志如下:

query: /hello2 thread=
search041142.sqa.cm4.tbsite.net – - [15/May/2014 15:33:10] “GET /hello2 HTTP/1.1″ 200 -
socket.error : Connection broke. Aborting[Errno 32] Broken pipe
—————————————-
Exception happened during processing of request from ('10.232.41.142′, 48769)
Traceback (most recent call last):
File “/home/wuzhu/tools/python_2_7_1/lib/python2.7/SocketServer.py”, line 582, in process_request_thread
self.finish_request(request, client_address)
File “/home/wuzhu/tools/python_2_7_1/lib/python2.7/SocketServer.py”, line 323, in finish_request
self.RequestHandlerClass(request, client_address, self)
File “/home/wuzhu/tools/python_2_7_1/lib/python2.7/SocketServer.py”, line 639, in __init__
self.handle()
File “/home/wuzhu/tools/python_2_7_1/lib/python2.7/BaseHTTPServer.py”, line 337, in handle
self.handle_one_request()
File “/home/wuzhu/tools/python_2_7_1/lib/python2.7/BaseHTTPServer.py”, line 326, in handle_one_request
 self.wfile.flush() #actually send the response if not already done.
File “/home/wuzhu/tools/python_2_7_1/lib/python2.7/socket.py”, line 303, in flush
self._sock.sendall(view[write_offset:write_offset+buffer_size])
AttributeError: 'NoneType' object has no attribute 'sendall'

2. 原因分析

“[Errno 32] Broken pipe “ 产生的原因还是比较明确的,由于 client 在服务器返回前主动断开连接,所以服务器在返回时写 socket 收到SIGPIPE报错。虽然在我们的程序中也对异常进行了处理,将handler 的 wfile._sock 对象close 掉 ,但python 的库里BaseHTTPServer.py中BaseHTTPRequestHandler 类的成员函数handle_one_request还是会直接调用 wfile.flush ,而没有判断 wfile 是否已经 close。

def handle_one_request(self):
    """Handle a single HTTP request.
 
    You normally don't need to override this method; see the class
    __doc__ string for information on how to handle specific HTTP
    commands such as GET and POST.
 
    """
    try:
        self.raw_requestline = self.rfile.readline(65537)
        if len(self.raw_requestline) > 65536:
            self.requestline = ''
            self.request_version = ''
            self.command = ''
            self.send_error(414)
            return
        if not self.raw_requestline:
            self.close_connection = 1
            return
        if not self.parse_request():
            # An error code has been sent, just exit
            return
        mname = 'do_' + self.command
        if not hasattr(self, mname):
            self.send_error(501, "Unsupported method (%r)" % self.command)
            return
        method = getattr(self, mname)
        method()
        #没有判断 wfile 是否已经 close 就直接调用 flush()
        self.wfile.flush() #actually send the response if not already done.
    except socket.timeout, e:
        #a read or a write timed out.  Discard this connection
        self.log_error("Request timed out: %r", e)
        self.close_connection = 1
        return


3. 解决办法

只要在RequestHandler重载其基类BaseHTTPRequestHandler的成员函数handle_one_reques(),在调用 wfile.flush() 前加上 wfile 是否已经 close 即可。

 
#!/usr/bin/env python
#!coding=utf-8

import os
import time
import socket
import threading
from BaseHTTPServer import HTTPServer ,BaseHTTPRequestHandler
from SocketServer import ThreadingMixIn

class RequestHandler(BaseHTTPRequestHandler):
    
    def handle_one_request(self):
        """Handle a single HTTP request.
 
        You normally don't need to override this method; see the class
        __doc__ string for information on how to handle specific HTTP
        commands such as GET and POST.
 
        """
        try:
            self.raw_requestline = self.rfile.readline(65537)
            if len(self.raw_requestline) > 65536:
                self.requestline = ''
                self.request_version = ''
                self.command = ''
                self.send_error(414)
                return
            if not self.raw_requestline:
                self.close_connection = 1
                return
            if not self.parse_request():
                # An error code has been sent, just exit
                return
            mname = 'do_' + self.command
            if not hasattr(self, mname):
                self.send_error(501, "Unsupported method (%r)" % self.command)
                return
            method = getattr(self, mname)
            print "before call do_Get"
            method()
            #增加 debug info 及 wfile 判断是否已经 close
            print "after call do_Get"
            if not self.wfile.closed:
                self.wfile.flush() #actually send the response if not already done.
            print "after wfile.flush()"
        except socket.timeout, e:
            #a read or a write timed out.  Discard this connection
            self.log_error("Request timed out: %r", e)
            self.close_connection = 1
            return
    
    def do_GET(self):
        """
        处理get请求
        """
        query=self.path
        print "query: %s thread=%s" % (query, str(threading.current_thread()))
 
        ret_str="<html>" + self.path + "<br>" + str(self.server) +  "</html>"
 
        time.sleep(5)
        
        try:
            self.send_response(200)
            self.send_header('Content-type','text/html')
            self.end_headers()         
            self.wfile.write(ret_str)
        except socket.error, e:
            print "socket.error : Connection broke. Aborting" + str(e)
            self.wfile._sock.close()
            self.wfile._sock=None
            return False
       
        print "success prod query :%s" % (query)
        return True
 
#多线程处理
class ThreadingHTTPServer(ThreadingMixIn,HTTPServer):
    pass
    
if __name__ == '__main__':
    serveraddr = ('',9001)
 
    ser = ThreadingHTTPServer(serveraddr,RequestHandler)
    ser.serve_forever()
    sys.exit(0)


运行服务
./thread_http_server.py
curl ,不等待返回,ctrl +C 来模拟客户端断开

[~]$curl -s 'http://10.232.41.142:9001/hello2'
[~]$ ctrl+C


此时服务器端输出日志如下:

$./thread_http_server.pybefore call do_Get
query: /hello2 thread=<Thread(Thread-1, started 1103210816)>
search041142.sqa.cm4.tbsite.net - - [15/May/2014 15:54:09] "GET /hello2 HTTP/1.1" 200 -
socket.error : Connection broke. Aborting[Errno 32] Broken pipe
after call do_Get
after wfile.flush()


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mpowal 发布于2015-07-28 10:43:08
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