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From Jason Lea <>
Subject Re: [DBCP] Strange Problems and Errors
Date Tue, 02 Apr 2002 08:18:17 GMT
I have tried using some of your settings, leaving out the validation 
test string and even tried closing a connection more than once.  But I 
can't get the number of active connections to go negative.

PoolableConnection.close() checks if it has been closed before 
(_closed=true).  If it has it throws an exception, otherwise it returns 
itself to the pool.  So it doesn't look like closing more than once can 
lead to this problem.

Looking at the code I have seen only 1 way (so far) to get a negative 
number of active connections.  It involves 

If you call this twice (or more) with the same object eg

Then each time numActive will be decremented.  In fact, you can call it 
with null eg connectionPool.invalidateObject(null), and it will also 
decrement the numActive.

It looks like it is used when you have a connection (or object) you know 
is bad eg threw an exception, and don't want it returned to the object pool.

It looks like you aren't using this from the code snippets you have 
shown, so it could be some other problem.

Jason Lea wrote:
> It's almost as if every time i call close it decrements, but nothing ever increments
> Could it be this problem that Jason stated below?
> Travis
> ---- Original Message ----
> From: Jason Lea <>
> Sent: 2003-04-01
> To: Jakarta Commons Users List <>
> Subject: Re: [DBCP] Strange Problems and Errors
> wrote:
>>Ok, I'm getting some strange behaviour with dbcp as detailed below: 
>>Here is the config for it: 
>>connectionPool = new GenericObjectPool(null); 
>>       connectionPool.setMaxActive(50); 
>>       connectionPool.setWhenExhaustedAction(GenericObjectPool.WHEN_EXHAUSTED_GROW);

>>       connectionPool.setMaxIdle(50); 
>>       connectionPool.setNumTestsPerEvictionRun(5); 
>>       connectionPool.setTestWhileIdle(true); 
>>       connectionPool.setTimeBetweenEvictionRunsMillis(20000); 
>>       connectionPool.setTestOnBorrow(true); 
>>       connectionPool.setTestOnReturn(false); 
>>       connectionPool.setMinEvictableIdleTimeMillis(-1); 
>>       DriverManagerConnectionFactory connectionFactory = new DriverManagerConnectionFactory(dbUrl,
>>       PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(connectionFactory,connectionPool,null,null,false,true);

>>       pool = new PoolingDataSource(connectionPool); 
> Not sure if this will fix the problem but I noticed you are not 
> supplying a validationQuery when you create the 
> PoolableConnectionFactory.  As you are testing the connection while idle 
> and testOnBorrow is also true, the pool should be running a test eg
> PoolableConnectionFactory poolableConnectionFactory = new 
> PoolableConnectionFactory(connectionFactory,connectionPool,null,"SELECT 
> test FROM testtable",false,true);

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