 | | | Application freezes after connection is dead | Application freezes after connection is dead 2006-07-20 - By Reinhard H?ttermann
Back
--Alt-Boundary-5992 (See http://ary-5992.ora-code.com).289331546
Content-type: text/plain; charset=ISO-8859 (See http://ISO-8859.ora-code.com)-1
Content-transfer-encoding: Quoted-printable
Content-description: Mail message body
Hi,
Problem description:
I use unixODBC-2 (See http://DBC-2.ora-code.com).2.8-55 containing the driver manager MyODBC-unixODBC-3 (See http://DBC-3.ora-code.com).51=
.06-150
within a SuSE Linux 9.1 (i586) operating system.
I create handles to open a "permanent" connection to a MySQL database with=
SQLConnect
in an application (in this case a middleware). I send SQL-Statements via t=
his connection and
receives an answer for each of them. This all works fine.
Then I simulate a problem with the LINUX command:
iptables -A INPUT -p tcp --destination-port mysql --source 10.128.64.56 -=
j REJECT
which interrupts the connection (I close the listening port of the databas=
e).
Trying the next SQL-Request with SQLExecDirect leads to a "frozen" applica=
tion, i.e. the
function SQLExecDirect never returns.
O.K., then I try to implement a workaround, i.e. I implement a timeout for=
the call of
SQLExecDirect to catch the frozen status of the function including a long =
jump to a function
to clean up the situation. It means I call SQLDisconnect(). But now this f=
unction never
returns, so the system is frozen again.
O.K. then I forget the clean up and try to establish a new connection with=
SQLConnect and
new handles. But again: the function freezes.
As a summary: After the connection is dead, every action on one of the obj=
ects (the
deallocation of the handles or a call of SQLDisconnect, SQLConnect, ...) r=
egarding the
connection leads to a non-responding application.
First question: Is there anybody who can tell me how to catch this situati=
on?
Second question: The usage of
sqlReturn =3D SQLGetEnvAttr(this->envHandle, SQL_ATTR_CONNECTION_DEAD,
&lConnectionStatus, sizeof(SQLINTEGER), NULL=
);
leads in any case to sqlReturn=3DSQL_ERROR
Why?
Thanks in advance for your help.
Reinhard H=FCttermann
-- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ------=
-- ---- ---- ---- ---- ---- ---- ---- ---- -----
HaCon Ing.-Ges. mbH Hannover, Germany
--Alt-Boundary-5992 (See http://ary-5992.ora-code.com).289331546--
|
|
|