Re: Multi-threaded OCI Application Does Not Scale
Date: 24 Jan 2003 02:20:33 -0800
Message-ID: <532afd4.0301240220.7631fdc8_at_posting.google.com>
Possibly, all the threads are using the same connection / session.
As one session can execute only one command at a time, a single
session used by all threads effectively makes it a single threaded
program! You can monitor this on the server side through V$SESSIONS to
see how many sessions your program has created.
If this is the problem, let each thread create a different session.
Anup Jalan
cary_at_nams.net (Cary Lapoint) wrote in message news:<6b0e1783.0301231314.1c05a725_at_posting.google.com>...
Rave Technologies
www.rave-tech.com
> Hello,
>
> I have written a multi-threaded (pthreads) OCI program that INSERT's
> large quantities of data into an Oracle database. It works very
> reliably but does not scale well at all. To be specific, as the
> number of threads increases, the total import rate decreases slightly!
> However, as the number of separate concurrent program instances
> (processes) increases, the total import rate increases almost linearly
> until maxing out available system resources. The issue is currently
> under review by Oracle Support, but since it is a severity 4 problem,
> it might never be resolved. These are the facts. Identical behavior
> has been observed on a Solaris system running Oracle 8.1.7.0.0 and a
> Linux box running Oracle 8.1.7.0.1. Each loader thread has its own
> dedicated environment handle created using OCIEnvCreate() with
> OCI_THREADED | OCI_ENV_NO_MUTEX | OCI_OBJECT and a single session.
> Timing code embedded in the program shows that all examined
> sub-operations except one actually do scale reasonably well.
> Unfortunately, the one that does not, the OCIStmtExecute() call that
> performs the array INSERT's, dominates the overall program
> performance. Has anyone observed this behavior before? Can anyone
> cite/describe a database-intensive multi-threaded OCI application that
> does scale well? Any advice? Should it even be necessary to use
> OCI_THREADED since I use completely separate environment handles
> (still a little unclear on this point)? Thanks in advance.
>
>
> Cary
Received on Fri Jan 24 2003 - 11:20:33 CET