"Grant Edwards" <gr....com> wrote:
> On 2007-08-23, Hendrik van Rooyen <m....ocorp.co.za> wrote:
>
> > While doing a netstring implementation I noticed that if you
> > build a record up using socket's recv(1), then when you close
> > the remote end down, the recv(1) hangs,
>
> I don't see that behavior running 2.4 on Gentoo.
I express myself badly - when I say "close down" I don't mean
"close down as in socket.close" I mean "close down as in click on the
tkinter window, or with keyboard interrupt" - sorry for the confusion
>
> > despite having a short time out of 0.1 set.
>
> What time out? A socket's recv method doesn't do timeouts.
If I set a time out, then the recv does not block,
but gives me a timed out exception.
>
> > If however, you try to receive more than one char, (I tested
> > with 3, did not try 2), then when you shut the remote end down
> > you do not get a time out, but an empty string - the normal
> > end of file, I suppose.
> >
> > Has anybody else seen this behaviour?
>
> No. recv(1) works fine for me (Python 2.4 under Gentoo).
> Perhaps you could post a minimal example that doesn't work for
> you?
I am now frustrated - its not as simple as I thought - my application
still only detects EOF if I do more than recv(1), but I cannot
demonstrate simply - anyway, I have modified your code to look more
like my program's code, and it follows below - if it does nothing else,
it should convince you that recv() *does* time out...
The receiver code below detects if I close the sending console window,
as well as control-c - Rats!
I will muck around with this more to see if I can get to the bottom of it,
as I can't see anything different between what is below and my program,
except that in both cases the comms are done in threads which are not
the main loop.
- Hendrik
------------------------------------------------------------------------
#!/usr/bin/python
#reader
import socket
HOST = 'Linuxbox' # Symbolic name meaning the local host
PORT = 57001 # Arbitrary non-privileged port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
socket.setdefaulttimeout(0.100)
s.listen(1)
conn, addr = s.accept()
print 'Connected by', addr
data = ''
while 1:
try:
data = data + conn.recv(1)
except socket.error,msg:
if 'timed out' in msg:
print msg
continue
else:
print 'socket error is',msg
break
if not data: break
if data.endswith('\n'):
print data
data = ''
print 'heigh ho the end has come!'
conn.close()
------------------------------------------------------------------------
------------------------------------------------------------------------
#!/usr/bin/python
# writer
import socket,time,random
HOST = 'Linuxbox' # Symbolic name meaning the local host
PORT = 57001 # Arbitrary non-privileged port
socket.setdefaulttimeout(0.100)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while True:
try:
print 'Attempting to connect to server'
s.connect((HOST, PORT))
break
except socket.error, msg:
time.sleep(5)
continue
print 'Connected - Time out is:',s.gettimeout()
data = "The quick brown fox jumps over the lazy dog 0123456789\n"
count = 0
while count < 500:
try:
s.send(data)
except socket.error,msg:
if 'timed out' in msg:
print msg
time.sleep(0.05)
continue
else:
print 'socket error is:',msg
break
print "tx:",len(data)
time.sleep(random.randint(200,800)/1000.0)
s.close()
------------------------------------------------------------------------
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