The biggest issue you will hit with the JDBC-ODBC bridge is that it is
single threaded. The mutex used by the driver will enter into deadlocks
with the lock the database is maintaining. For instance, assuming
pre-emptive environment
1) T1 enters the driver and aquires the mutex
2) T1 calls setAutocommit(false)
3) T1 releases the mutex
4) T1 aquires the mutex and inserts a row
5) T1 releases the mutex
6) Context switch
7) T2 enters the driver and aquires the mutex
8) T2 tries to select the data just inserted. Since it is not committed it
cannot be read and blocks
9) Blocking causes a Context Switch
10) T1 tries to enter the driver to call commit() but T2 owns the mutex
11) Context switch
12) T2 cannot read the uncommitted data
13) Context switch
14) .......
We now have a deadly embrace. These can happen very easily in single
threaded drivers and the database using locking. I strongly reccomend
avoiding the JDBC/ODBC bridge. You will see this most in containers that
implement <VENDOR> native threading </VENDOR>.
Dave Wolf
Internet Applications Division
Sybase
> -----Original Message-----
> From: A mailing list for Enterprise JavaBeans development
> [mailto:[EMAIL PROTECTED]]On Behalf Of Lauren Commons
> Sent: Tuesday, September 19, 2000 12:09 PM
> To: [EMAIL PROTECTED]
> Subject: Re: j2ee memory error
>
>
> Thanks.
> Yes, we are using the jdbc/odbc bridge (much to my regret
> ;-)
> Have you had the problem just with the j2ee server or
> with others (I'm planning on deploying with Orion)?
> > Are you using the JDBC/ODBC bridge driver. I found it had this
> problem -
> > and the only solution was to get the correct native driver (in my case
> > jConnect from Sybase)
> > HTH,
> >
> > Monica
> >
> > -----Original Message-----
> > From: Lauren Commons [mailto:[EMAIL PROTECTED]]
> > Sent: 18 September 2000 16:59
> > To: [EMAIL PROTECTED]
> > Subject: j2ee memory error
> >
> >
> > Sorry if this is slightly off topic:
> > While running j2ee (jdk1.2.2, on NT) I frequently am
> > getting a java application error: 'The instruction blah
> > blah referenced memory at yadah yadah. The memory could
> > not be "written"'.
> > I searched the Sun sit, and found references to bugs from
> > summer of 1999 that are closed now. Anyone have any
> > clues?
> >
> >
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