Hi Helen,

I read through some of your older stuff on mers about thread safety and
local connections.

At one point you mentioned that you were going to try and lump all the data
on it together into one article. Did you ever get a chance, and if so would
you happen to have the url handy?

I inherited a ton of threaded database applications that use local
connections exclusively (for IB 5.6), and thus am justifiably interested in
learning more about this subject. :)

Regards,


Bill Morrison

-----Original Message-----
From: Helen Borrie [mailto:helebor@...]
Sent: Friday, September 28, 2001 2:27 AM
To: IBObjects@yahoogroups.com
Subject: Re: [IBO] AVs in gds32.dll


At 10:28 AM 28-09-01 +0200, you wrote:

>Hi,
>
>we are using IBO as the database connection in a heavily multi-threaded
>application. We are using separate TIB_Session and a TIBODatabase for every
>thread (we need a TDataset compatible IBO dataset, so using TIBOQuery to
>access the tables).
>
>I could manage to get rid of the "cannot read from connection..." errors
>with creating the database with CreateForSession, but there is a regular
>(once in every 2-3 hours) error:
>
>"Access violation at address 4055EAC4 in module 'gds32.dll'. Read of

address

>00000004"

The important question is: are you making local database connections or
connecting via TCP/IP (LOCALHOST)?

If your web app (and therefore GDS32.dll) is on the same box as the database
server, connecting locally is NOT thread-safe. IB was never designed for
local use and LIBS was added late in its history as a developer tool. It
was never intended for deployment.

The problem comes because, with LIBS, the client and the server share the
same IPC space. If you connect your web app to the database using local
loopback (connecting localhost, or another servername using the localhost IP
address) you *don't* get this IPC space conflict and you won't get these
AVs.

If you are already using tcp/ip for the local connection (thus eliminating
this as the cause) I'd e suspicious about the version of gds32.dll you are
using...

Regards,
Helen

All for Open and Open for All
InterBase Developer Initiative · http://www.interbase2000.org
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