[英]Python closing sockets at random it seems
I've been looking and dealing with this issue for a week. 我一直在寻找和处理这个问题一个星期。 I have client code that causes select() to return a socket that has actually closed from external reasons throwing an error 9 BAD FILE DESCRIPTOR, however I tested the code from a different python file and CANNOT get it to error.
我有客户端代码,导致select()返回实际上由于外部原因而关闭的套接字,并抛出错误9错误的文件描述符,但是我测试了来自其他python文件的代码,无法将其出错。 Ive tried a million things.
我已经尝试了一百万件事情。 heres a snippet from the server:
这是服务器端的一段代码:
NOTE: This will work for a few iterations and then suddenly break, it errors out in the message_queue as key error due to the file descriptor breaking even tho a message/no message has a key for that socket present. 注意:这将工作几次迭代,然后突然中断,由于文件描述符甚至在消息/无消息都存在该套接字的键的情况下中断,因此它在message_queue中作为关键错误而出错。
#Create the socket to communicate with uWSGI applications
server_address = ('localhost', 10001)
server = create_server_socket(server_address)
#Sockets which we expect to read on from select()
input_sockets = [server]
#Sockets which we expect to write to from select()
output_sockets = []
#Message buffer dicitonary for outgoing messages
message_queue = {}
#Now wait for connections endlessly
while input_sockets:
print >> sys.stderr, "Waiting for the next event..."
readable, writable, exceptional = select.select(input_sockets, output_sockets, input_sockets)
#Handle input_sockets
for s in readable:
#Server socket is available for reading now
if s is server:
#Create a connection and address object when incoming request is recieved
connection, client_addr = s.accept()
print >> sys.stderr, "Connection recieved from %s!" % (client_addr,)
#Set client connection to non blocking as well
connection.setblocking(0)
#Add this socket to input sockets as it will read for client data
input_sockets.append(connection)
#Give connection a queue for sending messages to it
message_queue[connection] = Queue.Queue()
#A client has sent data so we can handle its request
else:
#Pull data from the client
data = ""
try:
while True:
message = s.recv(1024)
if not message:
break
data += message
except Exception as e:
print str(e)
if data:
#Readable client socket has data
print >> sys.stderr, 'Recieved "%s" from %s' % (data, s.getpeername())
message_queue[s].put(data)
#Add output channel now to send message
if s not in output_sockets:
output_sockets.append(s)
#There is no data to be read, socket must be closed
else:
print >> sys.stderr, 'Closing', client_addr,'after recieving no data.'
#Stop listening for input on the socket
if s in output_sockets:
output_sockets.remove(s)
input_sockets.remove(s)
#Close the connection
s.close()
del message_queue[s]
#Handle writable connections
for s in writable:
if s:
try:
next_message = message_queue[s].get_nowait()
except:
print >> sys.stderr, 'No data to send for', s.getpeername()
output_sockets.remove(s)
else:
try:
print >> sys.stderr, 'Sending "%s" to %s' % (next_message, s.getpeername())
s.sendall(next_message)
except:
print >> sys.stderr, 'No data to send for', s.getpeername()
output_sockets.remove(s)
#s.sendall('EOF:!@#$:EOF')
#Now handle any exceptions
for s in exceptional:
print >> sys.stderr, 'Handling exception on ', s.getpeername()
input_sockets.remove(s)
if s in output_sockets:
output_sockets.remove(s)
s.close()
#Remove any messages
del message_queue[s]
client: 客户:
messages = [ 'This is the message. ',
'It will be sent ',
'in parts.',
]
server_address = ('localhost', 10001)
# Create a TCP/IP socket
socks = [ socket.socket(socket.AF_INET, socket.SOCK_STREAM),
socket.socket(socket.AF_INET, socket.SOCK_STREAM),
]
# Connect the socket to the port where the server is listening
print >>sys.stderr, 'connecting to %s port %s' % server_address
for s in socks:
s.connect(server_address)
for message in messages:
# Send messages on both sockets
for s in socks:
print >>sys.stderr, '%s: sending "%s"' % (s.getsockname(), message)
s.send(message)
# Read responses on both sockets
for s in socks:
data = s.recv(1024)
print >>sys.stderr, '%s: received "%s"' % (s.getsockname(), data)
if not data:
print >>sys.stderr, 'closing socket', s.getsockname()
s.close()
NOTE: This client side is only to test and start passing messages. 注意:此客户端仅用于测试并开始传递消息。
There is a race in your code when a socket is returned as both readable and writable and you close the socket because the read returned 0 bytes. 当套接字以可读和可写方式返回并且关闭套接字时,代码中会出现争用,因为读取返回了0个字节。 In this case you remove the socket from
input_sockets
, output_sockets
and message_queue
but the closed socket is still in writable
and it will thus try to write to it inside the same iteration of the select loop. 在这种情况下,您可以从
input_sockets
, output_sockets
和message_queue
删除套接字,但是关闭的套接字仍然是writable
,因此它将尝试在select循环的同一迭代中writable
该套接字。
I have no idea if this is the race you'll see because you neither show debug output not did you say where you stumble over this EBADF. 我不知道这是否是一场比赛,因为您既没有显示调试输出,也没有说过在EBADF上遇到的困难。 To track similar problems down I recommend to augment your code with more debug information on where you close a socket and where you try to process a socket because it is readable or writable so that you actually find the exact place of the race when looking at the debug output.
为了追踪类似的问题,我建议您在代码中添加更多调试信息,以了解关闭套接字的位置以及尝试处理套接字的位置,因为该套接字可读或可写,以便您在查看套接字时能真正找到比赛的确切位置。调试输出。
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