socket freezes

[Luis P. Mendes]

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Hi,

I've developed a program that uses a socket to receive information 24h a
~ day.

The problem is that the socket seems to freeze. By that I mean the
program stops getting information but doesn't raise any error.

I tried to solve this by writing the following functions, in order to
try to start the socket connection again:

def keepAlive(self):
~ self.alive = 0
~ tnow = time.time()
~ if tnow - self.lastTime > 90: # last time got from last string
received from the socket
~ self.alive = 1

def reSocket():
~ print "socket has failed", time.strftime('%X', time.localtime())
~ time.sleep(60)
~ l=GServer() # new instance that contains the socket

reSocket is triggered when self.alive is 1.

But it hasn't solved my problem. These functions have effect only after
I do a ^C, and even then, the socket doesn't start to acquire new input.

Any clues you can give me about this?
Luis P. Mendes
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[Rene Pijlman]

Luis P. Mendes:

I've developed a program that uses a socket to receive information 24h a
~ day.

The problem is that the socket seems to freeze. By that I mean the
program stops getting information but doesn't raise any error.
That's weird. There's probably a bug in your program.
I tried to solve this by writing the following functions, in order to
try to start the socket connection again:

So now you have two problems. When there's a bug in your program, it's
usually best to hunt it down, rather than to add more code with more bugs
:-)

--
René Pijlman

[Steve Holden]

Luis P. Mendes wrote:

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Hi,

I've developed a program that uses a socket to receive information 24h a
~ day.

The problem is that the socket seems to freeze. By that I mean the
program stops getting information but doesn't raise any error.

I tried to solve this by writing the following functions, in order to
try to start the socket connection again:

def keepAlive(self):
~ self.alive = 0
~ tnow = time.time()
~ if tnow - self.lastTime > 90: # last time got from last string
received from the socket
~ self.alive = 1

def reSocket():
~ print "socket has failed", time.strftime('%X', time.localtime())
~ time.sleep(60)
~ l=GServer() # new instance that contains the socket

reSocket is triggered when self.alive is 1.

But it hasn't solved my problem. These functions have effect only after
I do a ^C, and even then, the socket doesn't start to acquire new input.

Any clues you can give me about this?

Try setting a default timeout on the socket, and if it times out
recontact the other system on a new socket. See socket.setdefaultimeout()

regards
Steve
--
Steve Holden [phone] [phone]
Holden Web LLC/Ltd www.holdenweb.com
Love me, love my blog holdenweb.blogspot.com

[Luis P. Mendes]

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| Try setting a default timeout on the socket, and if it times out
| recontact the other system on a new socket. See socket.setdefaultimeout()
|
| regards
| Steve

Thank you for your answers.

I'm beggining to suspect that the problem has to do with a discontinual
of service of the ISP. It provides me a dynamic IP address not a static
one.

I say this because after some hours, I returned to the computer and
could not acess the internet for surfing port 80 and the socket was also
down again - it just uses another port.

After unplugging the power cord of the cable modem from the internet and
pluging it in after a while, I could already access sites (http). But
the socket was still down, still with no error raised.

Based on this hypothesis, is there any way for my python program to deal
with this? Any thoughts?

Thanks again.

Luis
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[jordan.taylor2]

Might want to check out the SO_REUSEADDR bit in sockets. I believe it
helps with a problem of a program not notifying the OS that it's done
with the port.
Piece of a script (duh):

host = ""
port = 51423 #random for this example

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))

Good Luck :D

[Steve Holden]

Dennis Lee Bieber wrote:

On Fri, 03 Mar 2006 20:12:22 +0000, "Luis P. Mendes"
<lu***********@netvisaoXXX.pt> declaimed the following in
comp.lang.python:

I'm beggining to suspect that the problem has to do with a discontinual
of service of the ISP. It provides me a dynamic IP address not a static
one.

And many ISPs force a "lease renewal" after some period of time
(hours or days).

The DHCP protocol is supposed to allow lease renewal throughout the
lease period, and clients are normally expected to renew their lease
halfway through the lease period. So a continuously-connected system
should retain the same IP address.

If ISPs are *forcing* lease renewal they are perverting DHCP. Network
service should be continuous as long as a system remains continuously
connected. [...]

regards
Steve
--
Steve Holden [phone] [phone]
Holden Web LLC/Ltd www.holdenweb.com
Love me, love my blog holdenweb.blogspot.com

[Luis P. Mendes]

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Thank you all for your suggestions.

Luis P. Mendes
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