python-sybase-misc

[Python-sybase-misc] cursor.close() hangs

[Christophe C. <cc...@fr...>]

Hello,

I'm new to this list, and I'm currently trying to access an old windows Sybase 
ASA 7.0 from python/linux. I could make it work with freedts, but it hangs on 
some operation:

 >>> db=Sybase.connect(...)
 >>> c=db.cursor()
 >>> c.execute('select * from rue')
 >>> c.fetchone()
(...)
 >>> c.close()

here it hangs, nothing happens, with 0% CPU.
It only exits if I stop the database server:

Exception Sybase.DatabaseError: <Sybase.DatabaseError instance at 0xb7cf47cc> in 
<bound method _FetchLazy.__del__ of <Sybase._FetchLazy instance at 0xb7cf4e4c>> 
ignored

What is the recommended way to investigate this?
Did anyone have the same problem or is it trivial?

thanks,
Christophe

Re: [Python-sybase-misc] cursor.close() hangs

[Christophe C. <cc...@fr...>]

Christophe Combelles a écrit :
> Hello,
> 
> I'm new to this list, and I'm currently trying to access an old windows Sybase 
> ASA 7.0 from python/linux. I could make it work with freedts, but it hangs on 
> some operation:
> 
>  >>> db=Sybase.connect(...)
>  >>> c=db.cursor()
>  >>> c.execute('select * from rue')
>  >>> c.fetchone()
> (...)
>  >>> c.close()
> 
> here it hangs, nothing happens, with 0% CPU.
> It only exits if I stop the database server:
> 
> Exception Sybase.DatabaseError: <Sybase.DatabaseError instance at 0xb7cf47cc> in 
> <bound method _FetchLazy.__del__ of <Sybase._FetchLazy instance at 0xb7cf4e4c>> 
> ignored
> 
> What is the recommended way to investigate this?
> Did anyone have the same problem or is it trivial?
> 
> thanks,
> Christophe

more info:
I'm using python 2.4.4 with sybase-python 0.38 compiled with -D HAVE_FREETDS -U 
WANT_BULKCOPY, and freetds/libct4 0.64rc2.

it also hangs if I call again c.execute(...) after c.fetchone()

The last thing found in the freetds logfile (debug level 99) is:
-------------------------------------------------------
(...)
token.c:1863:tds_get_data: column 8, type 47, varint size 1
token.c:1920:processing row.  column size is 16
token.c:1863:tds_get_data: column 9, type 111, varint size 1
token.c:1920:processing row.  column size is 8
token.c:1863:tds_get_data: column 10, type 39, varint size 1
token.c:1920:processing row.  column size is 3
token.c:1863:tds_get_data: column 11, type 39, varint size 1
token.c:1920:processing row.  column size is 1
token.c:1863:tds_get_data: column 12, type 111, varint size 1
net.c:446:Received header
0000 04 01 00 11 00 00 00 00-                        |........|

net.c:542:Received packet
0000 fd 30 00 02 00 d1 04 00-00                      |.0...... .|

token.c:1920:processing row.  column size is 253

-------------------------------------------------------

If I hit Ctrl-C on the python terminal, the freetds logfile tells:

net.c:336:socket read interrupted
(as many times I hit Ctrl-C)


Is there a clue to say if this is an issue in freetds or python-sybase ?

Re: [Python-sybase-misc] cursor.close() hangs

[Christophe C. <cc...@fr...>]

Christophe Combelles a écrit :
> Christophe Combelles a écrit :
>> Hello,
>>
>> I'm new to this list, and I'm currently trying to access an old windows Sybase 
>> ASA 7.0 from python/linux. I could make it work with freedts, but it hangs on 
>> some operation:
>>
>>  >>> db=Sybase.connect(...)
>>  >>> c=db.cursor()
>>  >>> c.execute('select * from rue')
>>  >>> c.fetchone()
>> (...)
>>  >>> c.close()
>>
>> here it hangs, nothing happens, with 0% CPU.
>> It only exits if I stop the database server:
>>
>> Exception Sybase.DatabaseError: <Sybase.DatabaseError instance at 0xb7cf47cc> in 
>> <bound method _FetchLazy.__del__ of <Sybase._FetchLazy instance at 0xb7cf4e4c>> 
>> ignored
>>
>> What is the recommended way to investigate this?
>> Did anyone have the same problem or is it trivial?
>>
>> thanks,
>> Christophe
> 
> more info:
> I'm using python 2.4.4 with sybase-python 0.38 compiled with -D HAVE_FREETDS -U 
> WANT_BULKCOPY, and freetds/libct4 0.64rc2.
> 
> it also hangs if I call again c.execute(...) after c.fetchone()
> 
> The last thing found in the freetds logfile (debug level 99) is:
> -------------------------------------------------------
> (...)
> token.c:1863:tds_get_data: column 8, type 47, varint size 1
> token.c:1920:processing row.  column size is 16
> token.c:1863:tds_get_data: column 9, type 111, varint size 1
> token.c:1920:processing row.  column size is 8
> token.c:1863:tds_get_data: column 10, type 39, varint size 1
> token.c:1920:processing row.  column size is 3
> token.c:1863:tds_get_data: column 11, type 39, varint size 1
> token.c:1920:processing row.  column size is 1
> token.c:1863:tds_get_data: column 12, type 111, varint size 1
> net.c:446:Received header
> 0000 04 01 00 11 00 00 00 00-                        |........|
> 
> net.c:542:Received packet
> 0000 fd 30 00 02 00 d1 04 00-00                      |.0...... .|
> 
> token.c:1920:processing row.  column size is 253
> 
> -------------------------------------------------------
> 
> If I hit Ctrl-C on the python terminal, the freetds logfile tells:
> 
> net.c:336:socket read interrupted
> (as many times I hit Ctrl-C)
> 
> 
> Is there a clue to say if this is an issue in freetds or python-sybase ?
> 
> -------------------------------------------------------------------------

I have some news:
In fact, the ct_cancel command hangs in _FetchLazy.__del__ of Sybase.py,
when I call cursor.close() after several fetchone()
But this is a random effect, sometimes it hangs, sometimes not.
It might look like a threading issue.

I don't know what the real problem is, but I've tried to replace CS_CANCEL_ALL 
with CS_CANCEL_CURRENT or CS_CANCEL_ATTN, and it don't hangs anymore.

The difference between the different types of cancel is explained here:
http://manuals.sybase.com/onlinebooks/group-cnarc/cng1000e/prgguide/@Generic__BookTextView/5783;pt=6133
But I'm not sure what is the correct one in which circumstances.

regards,
Christophe

Re: [Python-sybase-misc] cursor.close() hangs

[Harri P. <har...@tr...>]

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Re: [Python-sybase-misc] cursor.close() hangs

[Christophe C. <cc...@fr...>]

Harri Pasanen a écrit :
> On Tuesday 17 July 2007 15:50:00 Christophe Combelles wrote:
>> Christophe Combelles a écrit :
>>> Hello,
>>>
>>> I'm new to this list, and I'm currently trying to access an old
>>> windows Sybase ASA 7.0 from python/linux. I could make it work
>>> with freedts, but it hangs on ...
>>>
> 
> Have you verified the "tds version" in .freetds.conf is correct for 
> that old sybase?

yes I did, and I have tried manny settings.
tds version must be 5.0 for this base

Christophe

> 
> Just a thought,
> 
> Harri
> 
> 
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