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

[omission9]

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)GetNumberRows()
-> def GetNumberRows(self):
(Pdb) s
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(28)GetNumberRows()
-> return len(self.data)
(Pdb) s
--Return--
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(28)GetNumberRows()->12
-> return len(self.data)
(Pdb) s
--Call--
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(30)GetNumberCols()
-> def GetNumberCols(self):
(Pdb) s
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(31)GetNumberCols()
-> if len(self.data) <= 0:
(Pdb) s
c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(34)GetNumberCols()
-> return len(self.data[0])
(Pdb) s
--Return--


c:\cygwin\home\ar881\development\bt_analysis\console\ndbbtable.py(34)GetNumberCols()->3
-> return len(self.data[0])
(Pdb) s

 

[Ziaran]

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.

Nir

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

 

[omission9]

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])

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

 

[Ziaran]

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?

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])

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