Re: Memory Leak

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Can you put System.gc() before or after the sleep?
The GC wil not run if you don't need the memory for something else.

Ronald.


Op vrijdag, 26 februari 2010 09:40 schreef William Taylor <[email protected]>:
> 
>  
> 
> On Feb 26, 2010, at 12:16 AM, Christopher G. Stach II wrote:
> 
> > 
> > ----- "William Taylor" <[email protected]> wrote:
> > 
> >> On Feb 25, 2010, at 11:44 PM, Christopher G. Stach II wrote:
> >>>> Working on some code where I select 4 million rows and store the
> >>>> results in a short array.
> >>> 
> 
> 
> Here is the test case. This is with the newest connector J 5.1.12
> 
> table name is test with a single smallint column.  4 million rows.
> 
> first console output shows 0mb used by the problem.
> each output after that shows ~255MB of ram used.
> regardless of how long you let the program run the GC never reclaims the memory.
> top says java is using ~289MB ram.
> mysqld shows ~7.4mb ram
> 
> public class Test
> {
> 
>     public static void main(String[] args) 
>     {
>         new Test();
>     }
>     
>     public Test()
>     {
>         System.out.println((Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory())/(1024*1024)+" MB");
>         
>         try 
>         {
>             Class.forName("com.mysql.jdbc.Driver").newInstance();            
>         } 
>         catch (InstantiationException e) 
>         {
>             e.printStackTrace();                        
>         } 
>         catch (IllegalAccessException e) 
>         {
>             e.printStackTrace();            
>         } 
>         catch (ClassNotFoundException e) 
>         {
>             e.printStackTrace();
>             System.exit(1);            
>         }
>         
>         try
>         {            
>             String url = "jdbc:mysql://localhost/yourDataBase";//?dontTrackOpenResources=true";
>             String userName = "username";
>             String password = "password";
>             
>             Connection connection = DriverManager.getConnection (url, userName, password);
>             PreparedStatement statement = connection.prepareStatement("select id from test");
>             ResultSet resultSet = statement.executeQuery();        
>             
>             resultSet.close();            
>             statement.close();
>             connection.close();
>         }
>         catch (SQLException e)
>         {
>             e.printStackTrace();
>         }    
>         
>         while(true)
>         {
>             try
>             {
>                 Thread.sleep(1000);
>             }
>             catch (InterruptedException e)
>             {
>                 e.printStackTrace();
>             }
>             
>             System.out.println((Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory())/(1024*1024)+" MB");
>         }
>     }
> }
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> 
> 


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