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From "Amila Suriarachchi" <amilasuriarach...@gmail.com>
Subject Re: Proposal for fixing out-of-memory error JIRA axis2-2968
Date Wed, 18 Jul 2007 05:15:30 GMT
On 7/17/07, Ann Robinson <robinsona@us.ibm.com> wrote:
>
> The Out-Of-Memory (OOM) error happens on a server with a large number of
> applications.  At deployment time, when the applications are loaded, the
> AxisService objects are created. For those applications where the loading
> ends up invoking the WSDL11ToAxisServiceBuilder, the wsdl is read in and
> saved as a Parameter on the AxisService object.  So, the OOM happens before
> requests start flowing.
>
> I tried a solution where the WSDLDefinition object is saved via
> serialization, so that it could be re-loaded when needed after deployment
> time. The javax.wsdl.Definition interface is supposed to implement the
> java.io.Serializable interface. However, the WSDLDefinition object fails
> to serialize. I speculate that the WSDLDefinition implementation has some
> internal tables or structures that don't support the default java
> serialization.
>
> I tried another solution with a wrapper on the WSDLDefinition object.  The
> wrapper, which is transparent to the user of the WSDLDefinition object,
> releases the heavyweight portions of the WSDLDefinition object.  If a
> component accesses the WSDLDefinition via the Parameter from the AxisService
> object, the wrapper can reload the WSDLDefinition.  This solution resolved
> the OOM problem - the server was able to load and start the applications
> successfully, and handle requests.
>
Did you tried the ?wsdl for wsdls having
1. imported wsdl in it
2. imported and included schemas on it
3. inline schemas on it
with useOriginalWSDL parameter set to true?

And wsdl2java generated code for above senarios?


I will create a patch with this solution so that it can be reviewed.

Ok. Please send a note to this thread as well.


> Ann
>
>
> On 07/16/2007 11:25 PM, *"Amila Suriarachchi" <amilasuriarachchi@gmail.com
> >* wrote:
>
>  > On 7/16/07, *Sanjiva Weerawarana* <*sanjiva@opensource.lk*<sanjiva@opensource.lk>>
> wrote:
>  > This is used for when useOriginalWSDL is true right?
>
> yes.
>
>
>    > I think the best thing is option (a) and have some policy for
>    taking it out of the server
>    > and re-loading it if it hasn't been hit for a while.
>    >
>    > I'm very much against option (c)- that's overkill for this problem
>    IMO.
>    >
>    > In any case, why is it leading to an OOM error? The WSDL should be
>    read
>    > once and then hung onto ... so unless the number of services is
>    growing
>    > arbitrarily large there's really no reason for the memory usage to
>    grow.
>    > I'm not convinced this is the reason for the OOM (unless for some
>    reason
>    > we keep creating new Definitions and never release the old one).
>
>
> yes.  this should not cause any OOM errors unless we load wsdl definition
> object per request. (then that is clearly an Axis2 bug). Ann are you getting
> the error at request processing time or deployment time?
>
> if it is at request processing time then we should creating wsdl
> definition objects per request and that should be an axis2 bug. What we
> supposed to do is to keep the original wsdl definition object and serialize
> it when user requested. But Here I think we can check for useOriginalWsdl
> parameter before storing that in memory to improve performance.
>
> if it is at deployment time none of above solutions would not solve the
> problem. Since we have to create the wsdlDefinition object at least once to
> create the axis object structure.
>
> thanks,
> Amila.
>
>    >>  On 15/07/07, Ann Robinson <*robinsona@us.ibm.com*<robinsona@us.ibm.com>>
>    wrote:
>    >>  >
>    >>  >
>    >>  > Hi, all,
>    >>  >  I've been investigating an out-of-memory error that happens
>    on the server
>    >>  > in some environments.  In analyzing the java heap dumps, one
>    of the biggest
>    >>  > consumers of memory is with the wsdl4j WSDLDefinition objects.
>     The heap
>    >>  > dump indicates that the WSDLDefinition uses the xerces dom for
>    underlying
>    >>  > support, particularly for schemas.  This makes the
>    WSDLDefinition very
>    >>  > heavy-weight.
>    >>  >
>    >>  >  The heap dump also shows that the WSDLDefinition objects of
>    concern are the
>    >>  > ones being saved in the AxisService's ParameterInclude list.
>     Comments in
>    >>  > the code (WSDL11ToAxisServiceBuilder) indicate that this is
>    done so that, if
>    >>  > some component needs to utilize the WSDLDefinition, the
>    component can access
>    >>  > it via a Parameter in the AxisService.
>    >>  >
>    >>  >  Is it possible to reduce the utilization of the
>    WSDLDefinition?
>    >>  >  Some ideas are:
>    >>  >  (a) releasing it when it is no longer needed
>    >>  >           - this might not be possible to determine
>    >>  >
>    >>  >  (b) putting a wrapper on the WSDLDefinition object
>    >>  >           - so that the WSDLDefinition,or a portion of the
>    WSDLDefinition,
>    >>  >             can be released
>    >>  >           - but if the WSDLDefinition is accessed after it was
>    released
>    >>  >             the wrapper can reload the WSDLDefinition
>    transparently to
>    >>  >             user
>    >>  >
>    >>  >  (c) create a layer for caching wsdl-related information
>    >>  >           - this would allow for releasing memory based on
>    some algorithm
>    >>  >             and/or interface that could indicate what's no
>    longer needed
>    >>  >
>    >>  >  Ann
>
>


-- 
Amila Suriarachchi,
WSO2 Inc.

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