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From "Brendan McAdams" <b.mcad...@themunicenter.com>
Subject HELP: DBI Issues
Date Fri, 06 Apr 2001 21:21:57 GMT
Hoping someone can help me; I'm working on rolling out a mod_perl
rewritten release (to push some major performance increases on our
application).

It works *beautifully* - our performance increase is up to 300% over
traditional CGI.

Unfortunately one of our sysadmins discovered a problem when he was
stress testing the system: If he clicks a link to one of the apps
components several times in succession, sybase's connections start
dying.

We have tried this with and without apache::dbi running.

As far as I can figure, what is happening is that when the client closes
its end (when it requests the new report, aborting the previous one),
mod_perl is terminating, but leaving the half processed result set
hanging in sybase.  Subsequent requests to Sybase start choking,
although after several minutes (5-10)  we see Sybase and mod_perl
usually straighten themselves out; this is unfortunately unacceptable.


I need to figure  out a way to handle the possibility of a client abort,
and gracefully close the result set (these are fairly large result sets
being returned from a stored procedure) without choking sybase.  This is
a critical release and I need to get this resolved as quickly as
possible.

An example of sybase errors:
[Fri Apr  6 17:02:50 2001] null: WARNING: Returning REPORT
SPECIFICATION.
[Fri Apr  6 17:02:50 2001] null: no statement executing at
/usr/local/apache/lib/perl/Apache/MuniCenter/MuniTable.pm line 342.
[Fri Apr  6 17:02:50 2001] null: DBD::Sybase::st fetchrow failed:
OpenClient message: LAYER = (4) ORIGIN = (1) SEVERITY = (5) NUMBER =
(28)
[Fri Apr  6 17:02:50 2001] null: Message String: ct_fetch(): protocol
specific layer: external error: There is a tds protocol error. An
illegal token was received.
[Fri Apr  6 17:02:51 2001] null: DBD::Sybase::st execute failed:
OpenClient message: LAYER = (4) ORIGIN = (1) SEVERITY = (5) NUMBER =
(28)
[Fri Apr  6 17:02:51 2001] null: Message String: ct_results(): protocol
specific layer: external error: There is a tds protocol error. An
illegal token was received.
[Fri Apr  6 17:02:51 2001] null: WARNING: Returning REPORT DETAILS.
[Fri Apr  6 17:02:51 2001] null: no statement executing at
/usr/local/lib/perl5/site_perl/5.005/sun4-solaris/DBI.pm line 1093.
[Fri Apr  6 17:02:51 2001] null: ct_cmd_alloc failed at
/usr/local/apache/lib/perl/Apache/MuniCenter/MuniTable.pm line 329.
[Fri Apr  6 17:02:51 2001] null: DBD::Sybase::st execute failed:
OpenClient message: LAYER = (1) ORIGIN = (1) SEVERITY = (1) NUMBER =
(50)
[Fri Apr  6 17:02:51 2001] null: Message String: ct_cmd_alloc(): user
api layer: external error: The connection has been marked dead.

Thanks,

Brendan

-----
Brendan W. McAdams           |   b.mcadams@themunicenter.com
Senior Applications Developer | (212) 208-9116
TheMuniCenter, LLC             | www.themunicenter.com

"Always listen to experts. They'll tell you what can't be done, and why.
Then do it."
- Robert A. Heinlein

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