need help with bizarre error caught in debugger. execution is hanging

Ziaran nir1408 at hotmail.com
Mon Feb 23 09:42:21 CET 2004


I guess it is a thread synchronization progblem
In that case some other thread modifies self.data leaving it empty in the
time between the if statement expression is evalutaed and the time the
return statement is executed.

Can this be the case?


"omission9" <omission9 at invalid.email.info> wrote in message
news:2uf_b.66535$1S1.50598 at nwrddc01.gnilink.net...
> Ziaran wrote:
> > Why do you do
> >
> > if len(self.data) <= 0:
> >     return len(self.data[0])
> >
> > Isn't that a sure IndexError exception?
> > Maybe you catch it somewhere up the stack and so you keep it silent.
> >
>
> That if statement just happens to be the last line before the return.
> What you have stated is not what actually happens.
> The actual code is
>          if len(self.data) <= 0:
>              return 0
>          else:
>              return len(self.data[0])
> I guess the "else" line doesn't appear in the stack trace for whatever
> reason.
> There is no doubt, however, that it is hanging on the line
> return len(self.data[0])
>
> >
> > "omission9" <omission9 at invalid.email.info> wrote in message
> > news:vfBZb.57526$1S1.32587 at nwrddc01.gnilink.net...
> >
> >>Any advice on the following would be much appreciated. I have thrown
> >>everything I have at it and am completely stumped. I apologize for the
> >>length, I have tried to be as succint as possible.
> >>
> >>I have a pythoncard/wxPython application. The application works well
> >>except that users were reporting occasional crashes. The application
> >>would simply stop and just hang. I was able to reproduce the bug
> >>faithfully and ran the application in the python debugger pdb.py.
> >>The trace is below and I simply cannot understand why it is hanging
> >>where it is. The application gets stuck executing
> >>
> >>return len(self.data[0])
> >>
> >>This works many many times during the applications execution, indeed
> >>several successful runs of this line are visible immediatley above the
> >>hang. I have also printed out the value of self.data. This is a list
> >>containing 12 inner lists each of length 3 at the point of the hang and
> >>is never larger than that.
> >>What on earth could cause this to stop the interpreter cold in its
> >>tracks without an exception being thrown? CPU usage on the machine is
> >>high throughout the application's execution and stays as such after the
> >>"hang" begins. I eventually kill the app although I have let it run for
> >>a long time and it never leaves this line.
> >>For what its worth, I am using python 2.3 on windows2k.
> >>
> >>Anyone have idea what could be happening?
> >>
> >>  c:\python23\lib\site-packages\wxpython\grid.py(664)_setOORInfo()->None
> >>  -> return val
> >>  (Pdb) s
> >>  --Return--
> >>   c:\python23\lib\site-packages\wxpython\grid.py(850)__init__()->None
> >>  -> self._setOORInfo(self)
> >>  (Pdb) s
> >>
> >>
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(17)__init
> >
> >>  __()
> >>  -> self.data = data
> >>  (Pdb) s
> >>
> >>
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(18)__init
> >
> >>  __()
> >>  -> self.colLabels = headings
> >>  (Pdb) s
> >>  --Return--
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(18)__init
> >
> >>  __()->None
> >>  -> self.colLabels = headings
> >>  (Pdb) s
> >>
> >>
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtablegrid.py(15)__
> >
> >>  init__()
> >>  -> self.colsizes = colsizes
> >>  (Pdb) s
> >>
> >>
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtablegrid.py(16)__
> >
> >>  init__()
> >>  -> self.SetTable(table, True)
> >>  (Pdb) s
> >>  --Call--
> >>  c:\python23\lib\site-packages\wxpython\grid.py(993)SetTable()
> >>  -> def SetTable(self, *_args, **_kwargs):
> >>  (Pdb) s
> >>  > c:\python23\lib\site-packages\wxpython\grid.py(994)SetTable()
> >>  -> val = gridc.wxGrid_SetTable(self, *_args, **_kwargs)
> >>  (Pdb) s
> >>  --Call--
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(27)GetNumb
> > erRows()
> >
> >>  -> def GetNumberRows(self):
> >>  (Pdb) s
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(28)GetNumb
> > erRows()
> >
> >>  -> return len(self.data)
> >>  (Pdb) s
> >>  --Return--
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(28)GetNumb
> > erRows()->12
> >
> >>  -> return len(self.data)
> >>  (Pdb) s
> >>  --Call--
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(30)GetNumb
> > erCols()
> >
> >>  -> def GetNumberCols(self):
> >>  (Pdb) s
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(31)GetNumb
> > erCols()
> >
> >>  -> if len(self.data) <= 0:
> >>  (Pdb) s
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(34)GetNumb
> > erCols()
> >
> >>  -> return len(self.data[0])
> >>  (Pdb) s
> >>--Return--
> >>
> >>
> >>
> >
> >
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(34)GetNumb
> > erCols()->3
> >
> >>  -> return len(self.data[0])
> >>  (Pdb) s
> >>
> >
> >
> >
>





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