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https://issues.apache.org/jira/browse/POOL-284?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14295696#comment-14295696
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Phil Steitz commented on POOL-284:
----------------------------------
They are wrapped "in the pool." The map that is causing the problem is the
allObjects map that is used to associate the PooledObject wrappers with the
unwrapped instances that are handed out to and received back from clients.
Since borrowObject returns an unwrapped object, returnObject needs to accept an
unwrapped instance and the pool needs to determine which PooledObject the
returning instance corresponds to. That is why allObjects uses "naked" objects
as keys and PooledObject wrappers as values.
> "Returned object not currently part of this pool" when using mutable objects
> ----------------------------------------------------------------------------
>
> Key: POOL-284
> URL: https://issues.apache.org/jira/browse/POOL-284
> Project: Commons Pool
> Issue Type: Bug
> Affects Versions: 2.2
> Reporter: Valentin Mayamsin
>
> I'm using pool to reuse expensive Sets (storing millions of items). Here is a
> test which fails:
> {code}
> GenericObjectPoolConfig config = new GenericObjectPoolConfig ();
> GenericObjectPool<Set> aPool = new GenericObjectPool<> ( new
> BasePooledObjectFactory<Set> ()
> {
> @Override
> public Set create () throws Exception
> {
> return new HashSet();
> }
> @Override
> public PooledObject<Set> wrap ( Set o )
> {
> return new DefaultPooledObject<> ( o );
> }
> @Override
> public void passivateObject ( PooledObject<Set> p ) throws
> Exception
> {
> p.getObject ().clear ();
> super.passivateObject ( p );
> }
> }, config );
> Set set = aPool.borrowObject ();
> set.add ( new Object () );
>
> aPool.returnObject ( set );
> {code}
> This is because GenericObjectPool uses a HashMap<Object, PooledObject> to
> correlate objects and state. HashMap stores objects correlated to their
> hashCode. So in case object's state change then hashCode will change, thus
> Map will fail to correlate this object since it stores old hashCode
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