I am trying to execute a query using postgre sql driver for java jdbc.
I have an issue with memory buildup my statement is in a loop and then sleeps.
The problem is when I look at the job in task manager I can see the memory climbing 00,004K at a time. I have read the documentation I have closed all connections statements resultsets but this still happens.
Please could you tell me what is causing this in my code.
String sSqlString = new String("SELECT * FROM stk.comms_data_sent_recv " +
"WHERE msgtype ='RECEIVE' AND msgstat ='UNPRC' " +
"ORDER BY p6_id,msgoccid " +
"ASC; ");
ResultSet rs = null;
Class.forName("org.postgresql.Driver");
Connection connection = DriverManager.getConnection(
"jdbc:postgresql://p6tstc01:5432/DEVC_StockList?autoCloseUnclosedStatements=true&logUnclosedConnections=true&preparedStatementCacheQueries=0&ApplicationName=P6Shunter", "P6dev",
"admin123");
//Main Loop
while(true)
{
try{
Statement statement = connection.createStatement();
statement.executeQuery(sSqlString);
//rs.close();
statement.close();
//connection.close();
rs = null;
//connection = null;
statement =null;
}
finally {
//connection.close();
}
try {
Thread.sleep(loopTime);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Notice the commented out code.. I did close all but that did not seem to make a difference. Whet I did see is that it seems that the statement executeQuery(sSqlString);
is causing this the reason I think so is if I remove the statement there is no memory leak.
I could be wrong but please assist me.
UPDATE:
I have changed my code as with your recommendations. Hope its a bit better please let me know if I need to change something.
My main loop :
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
//Main Loop
while(true)
{
getAndProcessAllUnprcMessagesFromStockList();
try {
Thread.sleep(loopTime);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
My Function it will call do fetch data :
public static void getAndProcessAllUnprcMessagesFromStockList() throws Exception
{
ResultSet rs = null;
Statement statement = null;
Connection connection =null;
String sSqlString = new String("SELECT * FROM stk.comms_data_sent_recv " +
"WHERE msgtype ='RECEIVE' AND msgstat ='UNPRC' " +
"ORDER BY p6_id,msgoccid " +
"ASC; ");
try{
Class.forName("org.postgresql.Driver");
connection = DriverManager.getConnection(
"jdbc:postgresql://p6tstc01:5432/DEVC_StockList?autoCloseUnclosedStatements=true&logUnclosedConnections=true&preparedStatementCacheQueries=0&ApplicationName=P6Shunter", "P6dev",
"admin123");
PreparedStatement s = connection.prepareStatement(sSqlString,
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_READ_ONLY);
rs = s.executeQuery();
while (rs.next()) {
//Process records
UnprcMsg msg = new UnprcMsg();
msg.setP6Id(rs.getString(1));
msg.setMsgOccId(rs.getString(2));
msg.setWsc(rs.getString(3));
msg.setMsgId(rs.getString(4));
msg.setMsgType(rs.getString(5));
msg.setMsgStatus(rs.getString(6));
//JOptionPane.showMessageDialog(null,msg.getP6Id(), "InfoBox: " + "StockListShunter", JOptionPane.INFORMATION_MESSAGE);
//msg2 = null;
}
rs.close();
s.close();
}
catch(Exception e)
{
e.printStackTrace();
}
finally
{
connection.close();
}
}
I have closed my connections statements and results. I also downloaded eclipse memory analyzer and I ran the jar witch will execute my main loop. Ran it for about an hour and here's some of the data I got from memory analyzer..
Leak suspects :
Now I know I cant go on the memory usage of task manager but whats the difference? Why does task manager show the following :
I was concerned about the memory usage I see in task manager? should I be?