Re: Don't use Connector/J 3.1 with Mysql 4.1.x
Posted by: Daniel Pereira
Date: February 28, 2005 04:54AM

I think why you have problems upgrading your database.

I did a litle program in java which makes queries to the database. Above is an example:

private void timer2OnTime(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String query="";int rvr21=0;
Statement stmt=null;
ResultSet result=null;
Connection con_bdee;

// System.out.println("TIMER2:START");
for(int i=0;i<100000;i++){
// METEO (rvr21)
try {
query="SELECT `value` FROM `tblMeteo` WHERE `name`='rvr21'";
stmt = con_bdee.createStatement();
result = stmt.executeQuery(query);;

} catch(SQLException ex) {
} catch(Exception xx){
System.out.println("TIMER2:EXCEPCÇÂO: BEGIN");
System.out.println("TIMER2:EXCEPCÇÂO: END");


Basically it make queries to the database, this method is running on timer (thread) with 500ms of interval, and i did another timer but with another query to another database. This program runs two threads at the same time.

When i run the program with the Connector/J 3.1.17 the memory of this program grows until it reaches the maximum memory (64Megas) and write "java.lang.OutOfMemory"

When i run the program with Connector/J 3.0.16 the memory stablizes and it didn't grows.

Reading again the documentation of the Connector, they recommended closing the statement and resultset of all queries. So, i append the following code to the try statement of the queries.

try{ result.close();}
catch(SQLException ex){ /*Nothing to do */ }
try{ stmt.close();}
catch(SQLException ex){ /*Nothing to do */ }

Using the Connector/J 3.1.17 the memory didn't grow.

Conclusion you must close all Statement if you want to use the version 3.1.17 of the Connector.

Note: If the resultSet isn't close the memory doesn't grow.
Note: Mysql 4.1.10 used

Is this a bug?
There is any way to prevent this wrong programing like the Connector/J 3.0.16(Closes automaticly the Statements cretated)?

I think, the crashes of the Dimitry program is a because a leak of memory. The queires i made to the database don't close the statements.

Now i'm using the Connector/3.0.16 and i have until now no problems

Best regards,
Daniel Pereira

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Re: Don't use Connector/J 3.1 with Mysql 4.1.x
February 28, 2005 04:54AM

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