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Date: Wed, 9 Jun 2010 10:44:33 +0800
Message-ID: <AANLkTiluvxmjZ1XyKWR2kprKU2C0qkZcnLy95au16aln@mail.gmail.com>
Subject: Re: PhantomReference in Cassandra
From: Anty <anty.rao@gmail.com>
To: dev@cassandra.apache.org
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In theory ,it could do some help.

On Sat, Jun 5, 2010 at 9:10 PM, Jonathan Ellis <jbellis@gmail.com> wrote:

> From what I have read, allowing the reference to be GC'd itself is
> equivalent to calling clear.  Does adding clear() make an observable
> difference?
>
> On Sat, Jun 5, 2010 at 1:31 AM, Anty <anty.rao@gmail.com> wrote:
> > ---------- Forwarded message ----------
> > From: Anty <anty.rao@gmail.com>
> > Date: Sat, Jun 5, 2010 at 4:30 PM
> > Subject: PhantomReference in Cassandra
> > To: user@cassandra.apache.org, chukwa-dev <chukwa-dev@hadoop.apache.org>
> >
> >
> > Hi:All
> > in the code of SSTableReader.java
> >  private static final ReferenceQueue<SSTableReader> finalizerQueue = new
> > ReferenceQueue<SSTableReader>()
> >    {{
> >        Runnable runnable = new Runnable()
> >        {
> >            public void run()
> >            {
> >                while (true)
> >                {
> >                    SSTableDeletingReference r = null;
> >                    try
> >                    {
> >                        r = (SSTableDeletingReference)
> > finalizerQueue.remove();
> >                        finalizers.remove(r);
> >                    }
> >                    catch (InterruptedException e)
> >                    {
> >                        throw new RuntimeException(e);
> >                    }
> >                    try
> >                    {
> >                        r.cleanup();
> >                    }
> >                    catch (IOException e)
> >                    {
> >                        logger.error("Error deleting " + r.path, e);
> >                    }
> >                }
> >            }
> >        };
> >        new Thread(runnable, "SSTABLE-DELETER").start();
> >    }};
> >
> >
> > the PhantomReference SSTableDeletingReference's cleanup() method doesn't
> > invoked clear() method inherited from Reference, whichi clear the phantom
> > reference to the referent.
> > but,the GC enqueues the PhantomReference onto ReferenceQueue before the
> > phantom reference clears. Is it necessary to invoke the clear() method
> after
> > r.clearup() or add clear() method in cleanup() method to accelerate the
> GC
> > process.
> >    try
> >                    {
> >                        r.cleanup();
> >                        r.clear();
> >
> >                    }
> >                    catch (IOException e)
> >                    {
> >                        logger.error("Error deleting " + r.path, e);
> >                    }
> > --
> > Best Regards
> > Anty Rao
> >
> >
> >
> > --
> > Best Regards
> > Anty Rao
> >
>
>
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of Riptano, the source for professional Cassandra support
> http://riptano.com
>


-- 
Best Regards
Anty Rao

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