Find Avalon Excalibur's Pool implementations in the
org.apache.avalon.excalibur.pool
package.
There are many implementations that are ThreadSafe, and
one that is not. You have the option of not limiting
used resources at all, or limiting the used resources
based on specific rules.
If you are using the Exalibur Component Management package,
you can have your components implement Poolable or Recyclable
from this package, and your components will be pooled. The
Components are pooled with a soft resource limiting pool.
That means that as additional resources are needed, they are
created--but once they are returned to the pool, the extra
instances are decommissioned.
The Excalibur DataSources package also uses this package,
and uses a hard resource limiting pool. If the number of
open JDBC Connections exceeds the limit, an exception is
thrown.