Your issue is a different from the performance increase Brad proposes.
He is talking about a BasicDataSource pool like system with PoolableConnectionFactory and a GenericObjectPool.
This pool is already optimized, the GenericKeyedObjectPool isn't.
I don't agree with your statement that the physical connection to the database needs to occur lazily and inside activateObject.
The physical connection should be created in makeObject but the pool should be optimized not to synchronize the calls to makeObject.
The maps in KeyedCPDSConnectionFactory have something to do with the jdbc2 ConnectionEvents (see cpdsadapter.ConnectionImpl.close()).
Some synchronization is needed to protect these maps.
-- Dirk
Todd Carmichael wrote:
The issue of high concurrency is very important to us as well. What I would
like to see is the narrowing of the synchronization in borrowObject to
include only grabbing a idle object or to making a new object and placing it
the pool. Activation of the object should NOT be sychronized. This is
because activation should not have anything to do with the maintenance of
the datastructures tracking the pool of objects themselves. The one
exception to this is testing an object that is being retrieved from the pool
for use (testOnBorrow): the failure case of this test would need to be
synchronized to handle removing the object from the pool.
In addition, the actual/physical connection to the database needs to occur
lazily and inside activateObject. Currently this occurs in makeObject. I
am speaking of the
org.apache.commons.dbcp.datasources.KeyedCPDSConnectionFactory and
org.apache.commons.pool.impl.GenericKeyedObjectPool. The synchronization of
the makeObject and that fact that it creates that actual physical database
connection causes serious degradation any time a new connection needs to be
created: no other call can execute borrowObject while a database connection
is being created which takes a long time.
I have done a couple prototypes to work around this but have not spent
enough time to get it fully functioning. Part of my problem is that I am
not familiar with nor understand the need for the WeakHashMap in
KeyedCPDSConnectionFactory and that the object PooledConnectionAndInfo uses
final members.
Anyway: +1 for removing the bottle neck on borrowObject when new objects need to be created.
ToddC
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