Re: Weird exception thrown

Frans is 100% correct as to the cause of the problem. You MUST call
Dispose on all objects coming out of the Oracle provider. I recommend
the use of the "using" statement to insure it's always done.

Marc

On Fri, Jan 9, 2009 at 11:11, Frans Bouma <[email protected]> wrote:
>> I have an application that reads an XML file, parses it and saves its data
>> into an Oracle database. The save is actually an insert, if the record
>> doesn't exist or an update if the record exists. In order to figure out
>> which operation I have to perform, I execute a select, to check whether
> the
>> record is already in the database. I build the Select SQL statement,
> create
>> an Oracle Command object with it and then call its Execute Reader method.
>> This method returns an OracleDataReader object and for that, all I care to
>> check is to see whether it has any records. The OracleDataReader class has
> a
>> property called "HasRows" that will tell me just that.
>> I know what you are thinking: I should ask this question on a different
>> forum, like one Oracle hosts for their ODP.NET development, but bare with
> me
>> for a second.
>> After running for 2-3 days continuously, my application starts throwing
> this
>> weird exception where it says that "Memory could not be allocated". I
>> managed to trace the raise of the exception to the invocation of the
>> "HasRows" property for the OracleDataReader object. The problem is that,
>> looking at the documentation, that property is not raising any exceptions,
>> so what the heck is going on.
>> To keep things under control, I even tried to kick in the garbage
> collection
>> (GC.Collect()) myself, every now and then. Now the exception takes longer
> to
>> be triggered, but eventually it is triggered.
>> Can anyone give me some ideas as to what else to try and figure out what
> the
>> problem is? The XML files are not really big, averaging around 100 kB
> each.
>> When the exception is triggered, I look ion the task manager and Physical
>> Memory usage is nowhere near the top.
>> Any suggestion will be highly appreciated.
>
>        Oracle's ODP.NET is actually a wrapper around their java CLI code,
> so it has unmanaged elements everywhere, even OracleParameter objects have
> unmanaged elements.
>
>        This means that you have to call Dispose() on
> - OracleParameter
> - OracleDataReader
> - OracleCommand
> - OracleConnection
>
>        It's not enough to call Dispose on OracleConnection or
> OracleCommand, nor is it enough to call Close on OracleDataReader.
>
>        If you don't do this, you'll get subtle memory leaks which
> eventually will bring the system down.
>
>        As you're using Oracle, you can do without the select however, use
> the MERGE statement:
> http://www.fast-track.cc/10g_166.htm
>        If you're on 9i you can use an upsert:
> http://www.praetoriate.com/oracle_tips_upserts.htm
>        If you're on an even older dinosaur (poor sod ;)), you're out of
> luck and will have to use the select separately.
>
>        Good luck.
>
>                FB
>
>
> ------------------------------------------------------------------------
> Lead developer of LLBLGen Pro, the productive O/R mapper for .NET
> LLBLGen Pro website: http://www.llblgen.com
> My .NET blog: http://weblogs.asp.net/fbouma
> Microsoft MVP (C#)
> ------------------------------------------------------------------------
>
>
>
>
>
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-- 
Marc C. Brooks
http://musingmarc.blogspot.com

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