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From "Kathey Marsden (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-210) Network Server will leak prepared statements if not explicitly closed by the user until the connection is closed
Date Tue, 07 Mar 2006 21:59:56 GMT
    [ http://issues.apache.org/jira/browse/DERBY-210?page=comments#action_12369318 ] 

Kathey Marsden commented on DERBY-210:
--------------------------------------

 I would like to suggest that we go ahead and commit Deepa's patch5, since it shows marked
improvement and no signs of regression.  Any objections?  If I hear nothing I will checkin
 later this afternoon.

John, it would be interesting to see the output of runtimeinfo at the 55 hour mark, to see
if it is really prepared statements leaking or something else.




> Network Server will leak prepared statements if not explicitly closed by the user until
the connection is closed
> ----------------------------------------------------------------------------------------------------------------
>
>          Key: DERBY-210
>          URL: http://issues.apache.org/jira/browse/DERBY-210
>      Project: Derby
>         Type: Bug
>   Components: Network Client
>     Reporter: Kathey Marsden
>     Assignee: Deepa Remesh
>  Attachments: DOTS_ATCJ2_Derby-noPatch.png, DOTS_ATCJ2_Derby-withPatch.png, StatementStress.java,
derby-210-patch1.diff, derby-210-patch2.diff, derby-210-patch2.status, derby-210-patch3.diff,
derby-210-patch4-v2.diff, derby-210-patch4-v2.status, derby-210-patch4-v3.diff, derby-210-patch4-v3.status,
derby-210-patch5-v1.diff, derby-210-patch5-v1.status, derby-210-v2-draft.diff, derby-210-v2-draft.status,
derbyStress.java
>
> Network server will not garbage collect prepared statements that are not explicitly closed
by the user.  So  a loop like this will leak.
> ...
> PreparedStatement ps;
>  for (int i = 0 ; i  < numPs; i++)
> 	{
> 	 ps = conn.prepareStatement(selTabSql);
> 	 rs =ps.executeQuery();
> 	 while (rs.next())
> 	{
> 	    rs.getString(1);
> 	}
> 	rs.close();
> 	// I'm a sloppy java programmer
> 	//ps.close();
> 	}
> 			
> To reproduce run the attached program 
> java derbyStress
> Both client and server will grow until the connection is closed.
>  
> It is likely that the fix for this will have to be in the client.  The client does not
send protocol to close the prepared statement, but rather reuses the PKGNAMCSN on the PRPSQLSTT
request once the prepared statement has been closed. This is how the server knows to close
the old statement and create a new one.

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