[Objectbridge-developers] Re: ConnectionManager

[Thomas M. <tho...@ho...>]

Hi Satish,
sa...@na... wrote:
> 
> Hi Thomas,
> 
> I have been noticing that lots of JDBC connections were getting
> created for simple queries using the same broker instance.
> 
> Then I noticed that new ConnectionManager
> instances were getting created for each query using the same broker
> instance. I inserted some debug statements and I think I might be
> seeing a bug.
> 
> Basically, since the connectionTable is empty for a new ConnectionManager
> (created in StatementsForClass), getNewConnection is called in
> ConnectionManager. Also curious is why the connectionManager object in
> PersistenceBroker was not being used?
> 
> I haven't had the time to put together a simple case that you can use.
> But, if you need, I will do so.
> 
> Please let me know.
> 
> If you do have a fix for this, can you mail it to me since I need to get
> this software out as soon as possible.
> 
Yes, this is definitely a bug. Sascha reported it some days ago and I
already prepared a fix.
As I did a lot of other internal changes in the meantime that won't be
compatible to your sources I can't send you the patched files.
But fortunately it's not difficult to do:
1. provide PersistenceBrokerImpl with a public method
getConnectionManager():
public ConnectionManager getConnectionManager()
{
   return m_ConnectionManager;
}

2. in the StamentsForClass constructor change the line
 ConnectionManager manager = new ConnectionManager(broker);

to:

 ConnectionManager manager = broker.getConnectionManager();
 
3. That's it! 

> Also, did you get a chance to look at my previous email regarding
> mysql wait_timeouts on idle connections and hence you can be left with
> stale connections in the pool (the server pool).
> 

Yes, but it's not easy to simulate this behaviour with instantdb. I
assume that the method java.sql.Connection.isClosed() will return true
or throws an SQLException in this case.
I will write some code that will use isClosed() to check if the
connection is still valid and will acquire a fresh one if necessary. The
fix will be in the next release. (by the end of the week)

HTH,

Thomas

> Thanks for all your help,
> Satish.
> 
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