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From Dain Sundstrom <>
Subject Re: [DBCP] DBCP-44 Deadlock
Date Fri, 20 Jul 2007 22:04:53 GMT
On Jul 20, 2007, at 11:26 AM, Dain Sundstrom wrote:

> On Jul 19, 2007, at 11:19 PM, Phil Steitz wrote:
>> I would love to have a fix for DBCP-44; but that could wait on pool
>> 1.4 if necessary (and Ipersonally see no way to fix it just within
>> dbcp.  It would be great if I was wrong on that).
> I think the makeObject method is over synchronized.  Actually, the  
> class doesn't look it's synchronized properly at all.  I'll take a  
> shot at fixing this.

I attached a patch that fixes the synchronization in  
PoolableConnectionFactory, but the deadlock still persists.  The  
problem is GenericObjectPool.borrowObject() is synchronized so when  
it needs to makeObject that method is called while the synchronized  
block is held.  I think this would take major surgery to make  
GenericObjectPool not perform this way.

I think the way to solve this is to write a new pool implementation  
that is much more async.  This easier with the Java5 concurrent  
packages, but still quite tricky.  I'll attempt to put together one  
in a few days.  Regardless, I don't think this is something we should  
target for this release.


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