commons-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Bernd Eckenfels (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (POOL-284) "Returned object not currently part of this pool" when using mutable objects
Date Wed, 28 Jan 2015 00:36:34 GMT

    [ https://issues.apache.org/jira/browse/POOL-284?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14294485#comment-14294485
] 

Bernd Eckenfels commented on POOL-284:
--------------------------------------

I think both (this and POOL-283) is by design of the generic implementation: users need to
have stable, idendity-preserving equals() and hashcode() implementations (like with normal
maps, too).

It might be possible to check for idendity and accept them anyway, but since the hashCode
has to be stable for managing them, I dont think it helps much.

I havent found this requirement documented in the Javadoc, not of the API/interfaces or the
generic implementation. One or both should state that. (I wonder if a implementation based
on IdendityHashMap for the generic pool would be fine or if this would be a more specific
pool).

> "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



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message