Re: Connection pool deadlock

Anil,

Other than re-coding which is the real solution; (There is no reason for
more than on connection per request) make sure your pool has multiple of
3 connections, ie 9, 12, 15, but not 10.

Dave
On Fri, 2003-02-28 at 00:25, Anil Kumar wrote:
> Hi All,
>
> I'm facing a problem with connection pooling. I'm using the
> pg73jdbc3.jar
> with PG 7.2 on RH 7.3.
>
> This is a Web application running on Tomcat. To render one of its
> pages it
> requires three concurrent connections to the database. It requests
> one
> connection after another and return them in the reverse order (the
> last
> obtained connection is returned first and so on). This creates a
> dead-lock
> if multiple requests are coming for this particular page. For
> example if
> the pool size is 10 and if the application is getting 4
> simultaneous
> requests for this page I found that the connection allocation
> happens in
> the following way:
>
> conn 1 -> request 1
> conn 2 -> request 2
> conn 3 -> request 3
> conn 4 -> request 4
> conn 5 -> request 1
> conn 6 -> request 2
> ...
> conn 10 -> request 2
>
> Here no request (or thread) will get enough number of connections
> to
> complete the request and all requests will go to an indefinite wait
> state.
> Of course this happens only when the connection requests reaches
> the pool
> capacity.
>
> I guess that some of you must have experienced this problem. What
> is the
> way out (other that re-coding the application to complete the
> request with
> single connection)?
>
> best regards
> Anil
>
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--
Dave Cramer <Dave(at)micro-automation(dot)net>