How to catch socket timeout?

[Achim Domma]

Hi,

I'm using Python 2.3s timeout sockets and have code like this to read a page
from web:

request = ...
self.page = urllib2.urlopen (request)

and later:

try:
self.data = self.page.read( )
except socket.error,e: ...
except socket.timeout: ...
except timeout: ...

but none of these excepts catches the the timeout while reading the data. I
still get the following exception, which I cannot handle:

....
File "F:\CrawlingFra mework\Rules\To ols\__init__.py ", line 91, in __init__
self.data = self.page.read( )
File "C:\Python23\li b\socket.py", line 283, in read
data = self._sock.recv (recv_size)
timeout: timed out

Any hint on how to handle this exception or what's going wrong?

regards,
Achim

[Peter Otten]

Achim Domma wrote:

I'm using Python 2.3s timeout sockets and have code like this to read a
page from web:

request = ...
self.page = urllib2.urlopen (request)

and later:

try:
self.data = self.page.read( )
except socket.error,e: ...
except socket.timeout: ...
except timeout: ...

but none of these excepts catches the the timeout while reading the data.
I still get the following exception, which I cannot handle:

socket.timeout is a subclass of socket.error, so the timeout exception
should be caught by the first except clause.

However, I could reproduce your uncaught exception with the following
minimalist code:

from urllib2 import urlopen
import socket

slowurl = "http://127.0.0.1/timeout?delay=1 00"
socket.setdefau lttimeout(1)
data = urlopen(slowurl )

try:
data.read()
except: # should catch ANY exception
print "Timeout raised and caught" # this never shows

So it seems there is *no* way to catch the error.
I think you should file a bug report.

Peter

[Achim Domma]

"Peter Otten" <__*******@web. de> wrote in message
news:bk******** *****@news.t-online.com...

So it seems there is *no* way to catch the error.
I think you should file a bug report.

Where/How do I do that?

Achim

[Alan Kennedy]

Peter Otten wrote:

socket.timeout is a subclass of socket.error, so the timeout exception
should be caught by the first except clause. So it seems there is *no* way to catch the error.
I think you should file a bug report.

Hmmm.

What is wrong with the following code? It seems to do what you need:

#============== =============== =============== ===========
from urllib2 import urlopen
import socket
import sys

slowurl = "http://127.0.0.1/cgi-bin/longWait.py?wai t=10"
socket.setdefau lttimeout(1)

try:
data = urlopen(slowurl )
data.read()
except socket.error:
errno, errstr = sys.exc_info()[:2]
if errno == socket.timeout:
print "There was a timeout"
else:
print "There was some other socket error"
#============== =============== =============== ==============

regards,

--
alan kennedy
-----------------------------------------------------
check http headers here: http://xhaus.com/headers
email alan: http://xhaus.com/mailto/alan

[Peter Otten]

Achim Domma wrote:

So it seems there is *no* way to catch the error.
I think you should file a bug report.

Where/How do I do that?

http://www.python.org/dev has an outside link to Bug Tracker leading to a
Sourceforge page where you can submit a short description of the bug.

Have a look at the list of bugs both to see if your bug has already been
submitted by others as well as for example submissions.
Peter

[Peter Otten]

Alan Kennedy wrote:

Hmmm.

What is wrong with the following code? It seems to do what you need:

#============== =============== =============== ===========
from urllib2 import urlopen
import socket
import sys

slowurl = "http://127.0.0.1/cgi-bin/longWait.py?wai t=10"
socket.setdefau lttimeout(1)

try:
data = urlopen(slowurl )
data.read()
except socket.error:
errno, errstr = sys.exc_info()[:2]
if errno == socket.timeout:
print "There was a timeout"
else:
print "There was some other socket error"
#============== =============== =============== ==============

You are right. I did not read the traceback carefully.

Peter

[Bob Halley]

"Achim Domma" <do***@procoder s.net> writes:

I'm using Python 2.3s timeout sockets and have code like this to read a page
from web:

request = ...
self.page = urllib2.urlopen (request)

and later:

try:
self.data = self.page.read( )
except socket.error,e: ...
except socket.timeout: ...
except timeout: ...

As another poster pointed out, socket.timeout is a subclass of
socket.error. (This was so you could write code that treated all
socket errors alike if you wanted timeouts but didn't need to deal
with them separately.)

Section 7.4 of the Language Reference says:

[...] When an exception occurs in the try suite, a search for
an exception handler is started. This search inspects the
except clauses in turn until one is found that matches the
exception. [...]

So, all you need to do is put the socket.timeout except clause before
any socket.error clause:

try:
self.data = self.page.read( )
except socket.timeout: ...
except socket.error,e: ...

/Bob

[Achim Domma]

"Bob Halley" <ha****@play-bow.org> wrote in message
news:ma******** *************** ***********@pyt hon.org...

So, all you need to do is put the socket.timeout except clause before
any socket.error clause:

try:
self.data = self.page.read( )
except socket.timeout: ...
except socket.error,e: ...

Thanks, that works fine, but I don't understand why the exception was not
catched in my case. If I write it like this

try:
self.data = self.page.read( )
except socket.error,e: ...
except socket.timeout: ...

the exception should be catched by the socket.error handler. Or am I wrong?
In my case it was not catched at all. Very mysterious from my point of view,
but it works now.

Achim

[Peter Otten]

Achim Domma wrote:

"Bob Halley" <ha****@play-bow.org> wrote in message
news:ma******** *************** ***********@pyt hon.org...

So, all you need to do is put the socket.timeout except clause before
any socket.error clause:

try:
self.data = self.page.read( )
except socket.timeout: ...
except socket.error,e: ...

Thanks, that works fine, but I don't understand why the exception was not
catched in my case. If I write it like this

try:
self.data = self.page.read( )
except socket.error,e: ...
except socket.timeout: ...

the exception should be catched by the socket.error handler. Or am I
wrong? In my case it was not catched at all. Very mysterious from my point
of view, but it works now.

Achim

Achim, both you and me got it wrong the first time. The important part is to
put both urlopen() and page.read() into the try clause, as Alan Kennedy has
already shown. Both statements can throw a timeout exception, so it's sheer
luck that it worked this time.
And yes, if you put

except socket.error:

before

except socket.timeout:

the latter will never be executed. General structure:
from urllib2 import urlopen
import socket

slowurl = "http://127.0.0.1/timeout?delay=1 00"
socket.setdefau lttimeout(1)

try:
data = urlopen(slowurl )
data.read()
except socket.timeout:
print "Timeout raised and caught"

Peter

[Paul]

What's the best way to do this under Python 2.1?
I believe socket.timeout was a 2.3 feature.
Wrap it in threads?

I'd like to do something similar for the Gibraltar
Linux firewall CD, but it only comes with Python 2.1.

Many thanks in advance.

-- Paul