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From "Phil Steitz (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (POOL-284) "Returned object not currently part of this pool" when using mutable objects
Date Sun, 22 Feb 2015 20:57:11 GMT

     [ https://issues.apache.org/jira/browse/POOL-284?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Phil Steitz updated POOL-284:
-----------------------------
    Attachment: StaticBucketMap-mods.patch

Diff showing mods on the original Collections class.  Objective was to use system identity
hash codes as hash codes for keys and force reference equality checks.  Also, eliminate dependencies
on other Collections classes.  This class could be stripped down further if we decide to go
this route.

> "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
>         Attachments: StaticBucketMap-mods.patch, pool-283-4.patch
>
>
> 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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