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JDBC Connection object lifetime / timeout?

Shane Paul
Greenhorn

Joined: May 04, 2009
Posts: 1
Hi,

I am using the latest JDBC 5 connector to connect to MySQL. Everything works swimmingly, most of the time !!!.

I wrote my own ConnectionPool.java class that basically creates 20
connections in a queue and manages checkin/ out of JDBC connections by the
application.

...
...
...
connectionQueue = new LinkedBlockingQueue<Connection>(20);

while(connectionQueue.remainingCapacity(...
tempConnection = DriverManager.getConnection(URL,
UserName, Password);
connectionQueue.add(tempConnection);
}

...
checkin()
checkout(Connection c)
...

This works fine most of the time, even under high use/pressure... However...if I leave the program running but idle for an extended
while... where basically it's just in a listening state and none of the
connections are getting taken and they are all residing in the
Pool...whenever a new message arrives and it requires a connection to the DB
i always get error:

mysql.jdbc.exceptions.jdbc4.Communicat... Communication link
failure

A program restart will fix immediately. I'm guessing the idle time is the key here with
the connections somehow dying, getting corrupt, exceeded time to live
etc or something...? but I've no idea how to fix...

All suggestions very welcome
Thanks
Jan Cumps
Bartender

Joined: Dec 20, 2006
Posts: 2516
    
  10

Shane,

the best way to fix it, is to use one of the existing connection pooling libraries. They have built in mechanisms to check connection health before giving the connection to your application.

You could build in this functionality in your own connection pool:
Before handing over a connection, execute a small sql statement with that connection.
If it returns, you can give the connection to the application.
If it fails, throw away the connection, replace it with a fresh one, and give it to the application.

Regards,


OCUP UML fundamental and ITIL foundation
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subject: JDBC Connection object lifetime / timeout?