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From "Deepa Remesh (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 Mon, 20 Feb 2006 21:50:06 GMT
    [ http://issues.apache.org/jira/browse/DERBY-210?page=comments#action_12367089 ] 

Deepa Remesh commented on DERBY-210:
------------------------------------

Thanks Kathey for the test case. I got what you are trying to say and I am working on making
the changes. However, I could not verify your test case with the current client code (I could
verify it with few changes just for testing). With current client code, if we don't close
a result set explicitly, it's statement object will not be freed. This is because result set
gets added to 'positionedUpdateCursorNameToResultSet_'  table in SectionManager. The result
set object gets removed from this table only when ResultSet.markClosed() gets called. So the
test you suggested cannot check the status of objects on network server since the current
client-side cleanup itself is not complete. This issue is listed in DERBY-817. 

> 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, 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-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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