Re: Fix for a bug in ManagedMemoryDataSource

[Davanum Srinivas <da...@gmail.com>]

Ananth,

Can you please open a bug report in JIRA
(http://issues.apache.org/jira) and submit the patch (guidelines at
http://nagoya.apache.org/wiki/apachewiki.cgi?AxisProjectPages/SubmitPatches).
So that we don't forget this patch/fix.

thanks,
dims


On Thu, 30 Sep 2004 16:24:12 +0100, Ananth Krishna
<ak...@it-innovation.soton.ac.uk> wrote:
> I am sending this mail to the developers list as I have noticed what
> seems to me like a bug in the ManagedMemoryDataSource class in axis1_2
> beta version. We are using javax.activation.DataHandler for soap
> attachments and are aware that axis manages data sources in 1_2 beta
> with the ManagedMemoryDataSource class.
> 
> Since then, we had also noticed that temp files created by axis when
> handling soap attachments weren't being cleaned up. Hence, we are
> explicitly calling 'delete' method on ManagedMemoryDataSource after
> ensuring that the data source returned from javax.activation.DataHandler
> is of the right type.
> 
> For small attachments up to a few kilobytes this worked well but when we
> try to upload larger soap attachments of the order of 5-6 megabytes the
> delete operation on ManagedMemoryDataSource complained with a
> java.util.ConcurrentModificationException on a WeakHashMap used in this
> class.
> 
> I dug deeper into the code and didn't quite realise why a WeakHashMap
> was used here but it seemed to me that there can be a potential race
> condition here and we seem to be hitting it by uploading larger soap
> attachments.
> 
> The delete() method of the main ManagedMemoryDataSource class, while
> iterating over the elements of the defined WeakHashMap, deletes elements
> of the WeakHashMap. As most of us know, this usually is a cause for
> ConcurrentModificationException to be thrown on HashMaps/WeakHashMaps.
> 
> Deleting elements in the WeakHashMap is actually done in the close()
> method of the private class inside ManagedMemoryDataSource which is
> invoked from the delete() method. As the close() method is used all over
> the place in this class, I have created a separate closeStream() method
> which doesn't attempt to delete/modify elements of this HashMap and is
> invoked as before from inside the delete method. This shouldn't affect
> elements of the HashMap being removed as the HashMap is cleared at the
> end of the delete() method anyway.
> 
> I am submitting the changes I have done to this class with this email.
> We have tested this class in the context that I have just described and
> it seems to work well and were hoping this patch can be included in the
> next release of axis..
> 
> Thanks & Regards
>  Ananth
> 
> Ananth Krishna
> IT Innovation Centre
> 2 Venture Road
> Chilworth Science Park
> Southampton, SO16 7NP, UK
> 
> tel:  +44 23 8076 0834
> fax: +44 23 8076 0833
> 
> mailto:ak@it-innovation.soton.ac.uk
> http://www.it-innovation.soton.ac.uk
> 
> 
> 
> 



-- 
Davanum Srinivas - http://webservices.apache.org/~dims/