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Re: [eclipselink-users] Re: one connection for each request
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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
