Aborting a thread corrupts my SqlConnection (?)

30 Nov 2004 12:33 PM

Uri Dor

Hi,
I'm running a long query in a separate thread. If I abort that thread
and then I try to use the same connection string again, I get an
unexpected result.
Details:

the aborted thread runs a query that returns a resultset, using a
DataAdapter.
the query run afterwards is:
INSERT INTO Report_selection_ids DEFAULT VALUES; SELECT SCOPE_IDENTITY()

which usually returns an integer, but if executed after the resultset
query thread was killed, it returns what seems to be the 1st field of
the 1st record of the recordset, which happens to be a string.

I've seen posts on a similar problem in framework 1.0, which was
supposed to be fixed long ago.

I'm using framework 1.1 (no SP - is there one?)

thx
Uri

30 Nov 2004 12:55 PM

Miha Markic [MVP C#]

Show quote Hide quote

"Uri Dor" <tablul@newsgroups.nospam> wrote in message
news:u8LU0it1EHA.3336@TK2MSFTNGP11.phx.gbl...
> Hi,
> I'm running a long query in a separate thread. If I abort that thread and
> then I try to use the same connection string again, I get an unexpected
> result.
> Details:
>
> the aborted thread runs a query that returns a resultset, using a
> DataAdapter.
> the query run afterwards is:
> INSERT INTO Report_selection_ids DEFAULT VALUES; SELECT SCOPE_IDENTITY()
>
> which usually returns an integer, but if executed after the resultset
> query thread was killed, it returns what seems to be the 1st field of the
> 1st record of the recordset, which happens to be a string.
>
> I've seen posts on a similar problem in framework 1.0, which was supposed
> to be fixed long ago.
>
> I'm using framework 1.1 (no SP - is there one?)

Yes, there is sp1.
However, you really shouldn't kill threads - rather use sync mechanisms to
signal to thread to finish.
Btw, how exactly are you killing the thread?
Are you creating a new instance of conneciton object for the new query?

--
Miha Markic [MVP C#] - RightHand .NET consulting & development
SLODUG - Slovene Developer Users Group
www.rthand.com

1 Dec 2004 7:07 AM

Uri Dor

Thanks for your reply, Miha.
I installed sp1, but the problem is still reproducible.
I'm killing the thread using Thread.Abort() and treating the exception.
I'm not aware of any sync mechanism that can stop a
SqlDataAdapter.Fill() call - are you?
Regarding the connections - the killed thread uses its own SqlConnection
instance, although it uses the same connection string so it's pooled.

What's the standard way to do such a thing - basically, to call
DataAdapter.Fill and then interrupt it?

Miha Markic [MVP C#] wrote:
Show quoteHide quote

> "Uri Dor" <tablul@newsgroups.nospam> wrote in message
> news:u8LU0it1EHA.3336@TK2MSFTNGP11.phx.gbl...
>
>>Hi,
>>I'm running a long query in a separate thread. If I abort that thread and
>>then I try to use the same connection string again, I get an unexpected
>>result.
>>Details:
>>
>>the aborted thread runs a query that returns a resultset, using a
>>DataAdapter.
>>the query run afterwards is:
>>INSERT INTO Report_selection_ids DEFAULT VALUES; SELECT SCOPE_IDENTITY()
>>
>>which usually returns an integer, but if executed after the resultset
>>query thread was killed, it returns what seems to be the 1st field of the
>>1st record of the recordset, which happens to be a string.
>>
>>I've seen posts on a similar problem in framework 1.0, which was supposed
>>to be fixed long ago.
>>
>>I'm using framework 1.1 (no SP - is there one?)
>
>
> Yes, there is sp1.
> However, you really shouldn't kill threads - rather use sync mechanisms to
> signal to thread to finish.
> Btw, how exactly are you killing the thread?
> Are you creating a new instance of conneciton object for the new query?
>

1 Dec 2004 8:58 AM

Miha Markic [MVP C#]

"Uri Dor" <tablul@newsgroups.nospam> wrote in message
news:eIwgJR31EHA.208@TK2MSFTNGP12.phx.gbl...
> Thanks for your reply, Miha.
> I installed sp1, but the problem is still reproducible.
> I'm killing the thread using Thread.Abort() and treating the exception.
> I'm not aware of any sync mechanism that can stop a SqlDataAdapter.Fill()
> call - are you?

No, there aren't.
However, you might throw an exception within RowChanged event (I am not sure
if this would stop the Fill process though).

> Regarding the connections - the killed thread uses its own SqlConnection
> instance, although it uses the same connection string so it's pooled.

Interesting.

>
> What's the standard way to do such a thing - basically, to call
> DataAdapter.Fill and then interrupt it?

Try the suggestion above and see what happens and let us know.

--
Miha Markic [MVP C#] - RightHand .NET consulting & development
SLODUG - Slovene Developer Users Group
www.rthand.com

2 Dec 2004 12:43 AM

Pablo Castro [MS]

Killing a thread is always dangerous. If at all possible you should avoid
doing that. One option for the Fill case is to try to use the Cancel()
method in the command object (adapter.SelectCommand.Cancel()). Depending on
where the command processing is, it may help.

--
Pablo Castro
Program Manager - ADO.NET Team
Microsoft Corp.

This posting is provided "AS IS" with no warranties, and confers no rights.

Show quoteHide quote

"Miha Markic [MVP C#]" <miha at rthand com> wrote in message
news:OvyOkP41EHA.3368@TK2MSFTNGP10.phx.gbl...
>
> "Uri Dor" <tablul@newsgroups.nospam> wrote in message
> news:eIwgJR31EHA.208@TK2MSFTNGP12.phx.gbl...
> > Thanks for your reply, Miha.
> > I installed sp1, but the problem is still reproducible.
> > I'm killing the thread using Thread.Abort() and treating the exception.
> > I'm not aware of any sync mechanism that can stop a
SqlDataAdapter.Fill()
> > call - are you?
>
> No, there aren't.
> However, you might throw an exception within RowChanged event (I am not
sure
> if this would stop the Fill process though).
>
> > Regarding the connections - the killed thread uses its own SqlConnection
> > instance, although it uses the same connection string so it's pooled.
>
> Interesting.
> >
> > What's the standard way to do such a thing - basically, to call
> > DataAdapter.Fill and then interrupt it?
>
> Try the suggestion above and see what happens and let us know.
>
> --
> Miha Markic [MVP C#] - RightHand .NET consulting & development
> SLODUG - Slovene Developer Users Group
> www.rthand.com
>
>