[unixODBC-support] Contention problem

Martin J. Evans bohica at ntlworld.com
Fri Apr 7 16:18:46 BST 2017


On 07/04/17 15:57, Reza Taheri wrote:
> On 4/7/17, 7:31 AM, Nick Gorham" <unixodbc-support-bounces at mailman.unixodbc.org <mailto:unixodbc-support-bounces at mailman.unixodbc.org> on behalf of nick at lurcher.org <mailto:nick at lurcher.org>> wrote:
>
>
>
> Probably worth asking the folk who wrote that driver. Are the threads sharing a connection handle? if they are I would expect that the socket that points to would be a limiting factor and expect it to all become serialised behind that.
>
> If you have a single connection and lots of statements, you could make the handle validation quicker by configuring with --enable-fastvalidate
>
>   1.95%  libodbc.so.2.0.0                 [.] __validate_stmt
>
> OK, I’ll try --enable-fastvalidate. If by driver you mean the PGSQL ODBC driver psqlodbcw.so, boy chasing the PGSQL folks in not the quick fix I was hoping for ☺. FWIW, if I am running with 80 threads of execution in the benchmark driver, I have 80 threads on the client, and there are 80 new postgres processes on the server. So I didn’t expect any sharing of connection data structures, but clearly something is being shared

If you are going to rebuild, make sure you disable stats as well.

Martin



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