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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 Wed, 08 Mar 2006 22:21:40 GMT
    [ http://issues.apache.org/jira/browse/DERBY-210?page=comments#action_12369556 ] 

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

I committed Deepa's patch5
Thank you so much Deepa for all your hard work on this issue and Bryan and John too.

Date: Wed Mar  8 13:16:49 2006
New Revision: 384331

URL: http://svn.apache.org/viewcvs?rev=384331&view=rev

I spoke with Deepa on IRC about the oustanding issues and possible Jira organization.

The current oustanding issues seem to be:
a) Prepared statements are not garbage collected on the server until the sections are reused.
(This has to be fixed with a DRDA protocol Change)
b) ResultSets are not garbage collected on the server until the section is reused. (This could
be fixed with DERBY-1021)
c) John found an issue with Statements not getting cleaned up at least in the server.

Would this sound like a reasonable course of action?
1) Open a subtask of this issue with the work Deepa has done so far and close it. Something
like:
"Change the client driver to allow statements to be garbage-collected once they are dereferenced
by an application"
2) Open a subtask of DERBY-210 for item a above.
3) Open an issue for "b" and make DERBY-1021 part of it or just close out DERBY-1021
4) Open a new issue for c



> 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, runtimeinfo_DOTS-OOME.txt
>
> 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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