2012.03.20. 8:08 keltezéssel, Laszlo Nagy írta:
Here you can find the example program and the original post.
http://code.activestate.com/lists/python-list/617894/
I gather you are running urlretrieve in a separate thread, inside a GUI?
Yes.
I have learned that whenever I have inexplicable behaviour in a
function,
I should check my assumptions. In this case, (1) are you sure you have
the right urlretrieve, and (2) are you sure that your self.Log() method
is working correctly? Just before the problematic call, do this:
# was:
fpath = urllib.urlretrieve(imgurl)[0]
# becomes:
print(urllib.__file__, urlretrieve)
self.Log(urllib.__file__, urlretrieve)
fpath = urllib.urlretrieve(imgurl)[0]
I called self.Log() after each line, and also from a general "except:"
clause. Definitely, the line after urlretrieve is not executed, and no
exception is raised. Number of threads goes up (visible from task
manager).
It is true that the program uses another module that uses the socket
module and multiple threads. (These are written in pure python.)
If I remove the other module, then there is no error, however it
renders the application useless. If I start the program with a console
(e.g. with python.exe instead of pythonw.exe) then it works. Looks
like opening a console solves the problem, although nothing is ever
printed on the console.
and ensure that you haven't accidentally shadowed them with something
unexpected. Does the output printed to the console match the output
logged?
Well, this cannot be tested. If there is a console, then there is no
problem.
What happens if you take the call to urlretrieve out of the thread and
call it by hand?
Then it works.
Run urllib.urlretrieve(imgurl) directly in the
interactive interpreter. Does it still hang forever?
Then it works perfectly.
When you say it "never" returns, do you mean *never* or do you mean "I
gave up waiting after five minutes"? What happens if you leave it to run
all day?
I did not try that. But I have already set socket timeout to 10
seconds, and definitely it is not waiting for a response from the server.
How big are the files you are trying to retrieve?
34 KB
Try retrieving a really small file. Then try retrieving a
non-existent file.
Good point. I'll try to retrieve a nonexistent file when I get home. :)
Today I got a different error message printed on console (program
started with python.exe)
Unhandled exception in thread started by <bound method
FrameLocEdit.GetThumbnail of <locedit.FrameLocEdit; proxy of <Swig
Object of type 'wxPanel *' at 0x4f85300>
>>Unhandled exception in thread started by <bound method
FrameLocEdit.GetThumbnail of <locedit.FrameLocEdit; proxy of <Swig
Object of type 'wxPanel *' at 0x4f85300>
>>Unhandled exception in thread started by <bound method
FrameLocEdit.GetThumbnail of <locedit.FrameLocEdit; proxy of <Swig
Object of type 'wxPanel *' at 0x4f85300>
>>Unhandled exception in thread started by
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
<bound method FrameLocEdit.GetThumbnail of <locedit.FrameLocEdit; proxy
of <Swig Object of type 'wxPanel *' at 0x4f85300>
>> File "C:\Python\Projects\Warehouserclient_v3\locedit.py", line 917,
in GetThumbnail
File "C:\Python\Projects\Warehouserclient_v3\locedit.py", line 917,
in GetThumbnail
File "C:\Python\Projects\Warehouserclient_v3\locedit.py", line 917,
in GetThumbnail
sys.excepthook is missing
Traceback (most recent call last):
I have never seen a traceback like this before. I didn't install any
excepthook myself.
Program is using wxPython, socket, threads, threading, PIL.
Here is something even more strange. If I click on the button three
times, then absolutely nothing gets printed on stdout. However, if I
close the program with file/exit (actually, calling
wx.PySimpleApp.ExitMainLoop) then suddenly three stack traces are
printed on stdout, all lines mixed up:
Unhandled exception in thread started by <bound method
FrameLocEdit.GetThumbnail of <locedit.FrameLocEdit; proxy of <Swig
Object of type 'wxPanel *' at 0x4fb530
0>
>>Unhandled exception in thread started by Unhandled exception in
thread started by <bound method FrameLocEdit.GetThumbnail of
<locedit.FrameLocEdit; proxy of <Swig Object of type 'wxPanel *' at
0x4fb5300>
>>Unhandled exception in thread started by Unhandled exception in
thread started by <bound method FrameLocEdit.GetThumbnail of
<locedit.FrameLocEdit; proxy of <Swig Object of type 'wxPanel *' at
0x4fb5300>
>>Traceback (most recent call last):<bound method
FrameLocEdit.GetThumbnail of <locedit.FrameLocEdit; proxy of <Swig
Object of type 'wxPanel *' at 0x4fb5300>
>>Traceback (most recent call last):<bound method
FrameLocEdit.GetThumbnail of <locedit.FrameLocEdit; proxy of <Swig
Object of type 'wxPanel *' at 0x4fb5300>
>>Traceback (most recent call last): File
"C:\Python\Projects\Warehouserclient_v3\locedit.py", line 917, in
GetThumbnail
Traceback (most recent call last):
File "C:\Python\Projects\Warehouserclient_v3\locedit.py", line 917,
in GetThumbnail
Traceback (most recent call last):
File "C:\Python\Projects\Warehouserclient_v3\locedit.py", line 917,
in GetThumbnail
File "C:\Python\Projects\Warehouserclient_v3\locedit.py", line
917, in GetThumbnail
File "C:\Python\Projects\Warehouserclient_v3\locedit.py", line
917, in GetThumbnail
self.Log(traceback.format_exc())
self.Log(traceback.format_exc())
self.Log(traceback.format_exc())
AttributeErrorself.Log(traceback.format_exc())
AttributeErrorself.Log(traceback.format_exc())
AttributeError: AttributeError: AttributeError:
C:\Python\Projects\Warehouserclient_v3>
And the last attributerror doesn't tell what attribute is missing.
Probably I'll have to use a different library (pycurl, for example). But
the error itself is getting more interesting.
Also tried to use an invalid file (that should return with HTTP 404 not
found) but the effect is exactly the same. Nothing is printed on stdout
until I try to close the program (stop wxPython's mainloop). Then all
previously threads throw an AttributeError and all of them print a stack
trace (at the same time, lines mixed up).
I'll be experimenting with pyCurl now.
Thanks,
Laszlo
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