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From Dirk Verbeeck <>
Subject Re: [Pool] GenericObjectPool release of resources during garbage coll ection
Date Wed, 10 Sep 2003 20:31:13 GMT
You are correct the GenericObjectPool doesn't have a finalize method.
There is a close method that does the cleanup but you have to call it 
You can of course subclass but using a finalizer is not recommended. 
Using a close method and making sure all your object are closed is much 
Relying on the GC to call your finalize method is not very good. It can 
take a long time before your network connection is closed and remember 
the GC is run when there is a low memory condition so it is very 
dangerous to create object inside a finalizer (iterators, messages to be 
send to the reciever, ...).
and of course you have to take threading / deadlocks into account... 
 very dangerous/difficult/untestable code

You will be better off designing something without finalizers.
Take a look DBCP, PoolableConnection for a nice design pattern for using 


Sy Andrew wrote:

>When an instance of GenericObjectPool is about to be garbage collected, does
>it release the objects/resources in its pool (e.g. by calling the
>PoolableObjectFactory.destroyObject(Object) method)? I plan to use
>GenericObjectPool to pool some objects, where each of these objects is
>holding on to a network connection. Ideally, the connections should always
>be closed cleanly. 
>Of course I can also implement finalize() on my own objects, or use a
>PhantomReference to the GenericObjectPool instance to ensure that this
>happens. But I just wanted to make sure first that GenericObjectPool is not
>already doing the work for me. I looked at the source code for
>GenericObjectPool and it did not seem to be doing this functionality. But
>since it's my first time looking at the code, can anyone confirm this?
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