Re: Re: one connection for each request

There is a configuration on the Connection Pool in Glassfish that allows you to associated the connection to the current thread of execution. This will allow for the connection to be reused when it is requested. Take a look at the ConnectionPool and check this option.

Chris Mathrusse

Yannick Majoros <yannick.majoros@...> Sent by: eclipselink-users-bounces@... 06/26/2009 06:37 AM Please respond to EclipseLink User Discussions <eclipselink-users@...>

To EclipseLink User Discussions <eclipselink-users@...> cc Subject Re: [eclipselink-users] Re: one connection for each request

Reinhard Girstenbrei a écrit :
>
> the fact that each query obtains it's own connection is intended
> behavior. This does guarantee that the application holds on a
> connection for the minimum amount of time and therefore it allows the
> most efficient use of precious physical connection resources. For sure
> you can get a ClientSession that obtains a connection and keeps it.
> You can also obtain an exlusive connection for read and write
> operations and keep it. But maybe the best solution is to use the
> connections lazily, the way you have observed EclipseLink to work.
>
>
Thank you for this information. But I still think something is wrong
and your advice could help me a lot.

If there is a new connection for each db request, even if one single
query generates a lot of requests, I guess they won't use the same
transaction? I would like to have all request in a transaction.

The EclipseLink queries are running in ejb session bean methods. I am
trying to get the transaction (UnitOfWork) which should be associated
with the injected EntityManager. Can I do this?

Here are some stats from glassfish jdbc pool monitoring:

Resource Statistics (14) Name                  Value                  Details                  Description
NumConnSuccessfullyMatched                  0 Count                  Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Number of Connections successfully
matched
NumConnUsed                  0 Count                  High Water Mark: 12 Count
Low Water Mark: 0 Count
Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides Connection usage statistics.
In addition to number of connections being used currently, this also
provides information about the Maximum number of connections that were
used(High Watermark).
WaitQueueLength                  0 Count                  Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides a count value indicating the
number of connection requests in the queue waiting to be servied.
NumConnDestroyed                  10 Count                  Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides a count value reflecting the
number of connections that were destroyed since the last sampling
ConnRequestWaitTime                  0 milliseconds                  High Water Mark: 16303 milliseconds
Low Water Mark: 0 milliseconds
Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides a range value that indicates
the longest, shortest wait times of connection requests since the last
sampling. The current value indicates the wait time of the last request
that was serviced by the pool.
NumConnFailedValidation                  0 Count                  Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides a count value reflecting the
number of connections in the connection pool that failed validation
since the start time till the last sample time.
NumConnReleased                  495643 Count                  Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides a count value reflecting the
number of connections released back to the pool since the last sampling
NumConnFree                  8 Count                  High Water Mark: 12 Count
Low Water Mark: 0 Count
Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides a count value reflecting the
number of connections in the connection pool that are free as of the
last sampling
NumPotentialConnLeak                  0 Count                  Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides a count value reflecting the
number of potential connection leaks
AverageConnWaitTime                  0 milliseconds                  Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Average wait time-duration per
successful connection request
NumConnTimedOut                  0 Count                  Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides a count value reflecting the
number of connections in the connection pool that timed out since the
start time till the last sample time.
NumConnCreated                  18 Count                  Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides a count value reflecting the
number of connections that were created by the pool since the last
sampling.
NumConnAcquired                  495643 Count                  Last Sample Time: 26 juin 2009 14:38:49
Start Time: 26 juin 2009 11:43:10                  Provides a count value reflecting the
number of connections acquired from the pool since the last sampling
NumConnNotSuccessfullyMatched                  0 Count                  Last Sample Time: 26 juin 2009
14:38:49
Start Time: 26 juin 2009 11:43:10                  Number of Connections rejected during
matching


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