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Re: [aspectj-users] problems with load time weaving and rmi communication 
Hi guys,

first of all thank you for your answers.
i did some testing with the aspectjweavers from aspectj final, from the current development build and from Rods expermintal build from glassbox inspector. The results are alarmingly different.

i did a little stress tests, that did about 3000 requests in a loop. without rmi rmi communication there is no significant memory usage. with rmi communication and rods development aspectjweaver i was able to send nearly 3000 requests. the memory usage went up to 500 MByte. with the aspectjweaver from the aspectj final build and from the actual development build i was only able to send nearly 500 requests. the memory usage went up to 500MByte and i got an out of memory error. rods experimental build made a significant difference in memory usage.

i summarized my results on the following url: http://www.webengineer.de/ltw.html
there you can find some screenhots from jconsole i made during my tests.

i also switched on the -verbose option in my aop.xml. as matthew mentioned before, when using rmi communication there are created a lot of class loaders. see the following i pasted from my tomcat console:

06.03.2006 10:17:36 myTest.DummyServlet doThis_aroundBody4
info AspectJ Weaver Version LTWExperimental built on Thursday Jan 26, 2006 at 03:39:19 GMT
info register classloader weblogic.utils.classloaders.GenericClassLoader@18880287
info using file:/C:/Programme/apache-tomcat-5.5.12/shared/lib/pmon-1.0.0-SNAPSHOT.jar!/META-INF/aop.xml
info register aspect de.pmon.PerformanceMonitor
info weaving 'myTest/bean/Service_ee9ogc_HomeImpl_814_WLStub'
info AspectJ Weaver Version LTWExperimental built on Thursday Jan 26, 2006 at 03:39:19 GMT
info register classloader weblogic.utils.classloaders.GenericClassLoader@32211177
info using file:/C:/Programme/apache-tomcat-5.5.12/shared/lib/pmon-1.0.0-SNAPSHOT.jar!/META-INF/aop.xml
info register aspect de.pmon.PerformanceMonitor
info weaving 'myTest/bean/Service_ee9ogc_EOImpl_814_WLStub'
06.03.2006 10:17:36 myTest.DummyServlet doThis_aroundBody4
06.03.2006 10:17:36 myTest.DummyServlet doThis_aroundBody4
info AspectJ Weaver Version LTWExperimental built on Thursday Jan 26, 2006 at 03:39:19 GMT
info register classloader weblogic.utils.classloaders.GenericClassLoader@20872473
info using file:/C:/Programme/apache-tomcat-5.5.12/shared/lib/pmon-1.0.0-SNAPSHOT.jar!/META-INF/aop.xml
info register aspect de.pmon.PerformanceMonitor
info weaving 'myTest/bean/Service_ee9ogc_HomeImpl_814_WLStub'
info AspectJ Weaver Version LTWExperimental built on Thursday Jan 26, 2006 at 03:39:19 GMT
info register classloader weblogic.utils.classloaders.GenericClassLoader@22373430
info using file:/C:/Programme/apache-tomcat-5.5.12/shared/lib/pmon-1.0.0-SNAPSHOT.jar!/META-INF/aop.xml
info register aspect de.pmon.PerformanceMonitor
info weaving 'myTest/bean/Service_ee9ogc_EOImpl_814_WLStub'
06.03.2006 10:17:36 myTest.DummyServlet doThis_aroundBody4
06.03.2006 10:17:36 myTest.DummyServlet doThis_aroundBody4
info AspectJ Weaver Version LTWExperimental built on Thursday Jan 26, 2006 at 03:39:19 GMT
info register classloader weblogic.utils.classloaders.GenericClassLoader@25411170
info using file:/C:/Programme/apache-tomcat-5.5.12/shared/lib/pmon-1.0.0-SNAPSHOT.jar!/META-INF/aop.xml
info register aspect de.pmon.PerformanceMonitor
info weaving 'myTest/bean/Service_ee9ogc_HomeImpl_814_WLStub'
info AspectJ Weaver Version LTWExperimental built on Thursday Jan 26, 2006 at 03:39:19 GMT
info register classloader weblogic.utils.classloaders.GenericClassLoader@10284000
info using file:/C:/Programme/apache-tomcat-5.5.12/shared/lib/pmon-1.0.0-SNAPSHOT.jar!/META-INF/aop.xml
info register aspect de.pmon.PerformanceMonitor
info weaving 'myTest/bean/Service_ee9ogc_EOImpl_814_WLStub'
06.03.2006 10:17:36 myTest.DummyServlet doThis_aroundBody4
06.03.2006 10:17:36 myTest.DummyServlet doThis_aroundBody4

can you explain me why it is necessary to register a new classloader on each rmi request?
we planned to integrate the permormance monitoring in one of our production systems. but as long as the memory increases on each rmi request we think it is not a good idea to integrate it. currently we only use it on our test systems (unfortunatley).

greetings,
thilo




Ron Bodkin wrote:

>Thilo,
>
>Just as a quick follow up, the AspectJ 1.5.0 release adds some nontrivial
>overhead per ClassLoader where you do weaving. When you are using RMI, the
>VM can create a lot of different ClassLoaders for reflective acessors.
>
>The experimental LTW version I pointed you at allows for sharing aspect
>definitions and AspectJ delegates between ClassLoaders where it is safe (it
>tests for nondelegation), so it should make a significant difference. I
>haven't yet created a patch for this optimization, since as Andy noted, I'm
>working with him to integrate some foundational memory improvements,
>bringing them up to generally usable production quality :-)
>
>The same issue applies for JSP's, where many containers create a large
>number of lightweight ClassLoaders and maintaining heavyweight weaving state
>for each results in major overhead.
>
>-----Original Message-----
>From: aspectj-users-bounces@xxxxxxxxxxx
>[mailto:aspectj-users-bounces@xxxxxxxxxxx] On Behalf Of Thilo Focke
>Sent: Friday, March 03, 2006 8:06 AM
>To: aspectj-users@xxxxxxxxxxx
>Subject: Re: [aspectj-users] problems with load time weaving and rmi
>communication
>
>Hi Matthew and Andy,
>
>1. The memory usage when using RMI without the aspect ist absolutely
>constant and in acceptable ranges (about 30-40 MByte). The memory usage
>increases permanently when using the aspect. When using the aspect on code
>without RMI communication the memory usage is constant (about 100MByte).
>
>2. IŽm using  AspectJ 1.5.0, released on 20th December, 2005
>
>3. My aop.xml looks like this
>
><!DOCTYPE aspectj PUBLIC "-//AspectJ//DTD//EN"
>"http://www.aspectj.org/dtd/aspectj_1_5_0.dtd";>
><aspectj>
>    <weaver options="-proceedOnError -noWarn
>-Xlintfile:META-INF/Xlint.properties">
>        <include within="my.package..*"/>      
>    </weaver>
>    <aspects>        
>        <aspect name="MyMonitor"/>
>    </aspects>
></aspectj>
>
>Thanks a lot,
>Thilo
>
> 
>
>
>--------------->
>
>Thilo,
>
>Can I ask some questions:
>1. What is the memory usage when you use RMI but not the aspect?
>2. Which version of AspectJ are you using? We have made some enhancements 
>recently in memory usage.
>3. Do you use -verbose in the weaver options of aop.xml? If so could you 
>post it. I think the problem might to do with creating lots of class 
>loaders, each with a weaver and the accompanying footprint.
>
>Cheers
>
>Matthew Webster
>AOSD Project
>Java Technology Centre, MP146
>IBM Hursley Park, Winchester,  SO21 2JN, England
>Telephone: +44 196 2816139 (external) 246139 (internal) 
>Email: Matthew Webster/UK/IBM @ IBMGB, matthew_webster@xxxxxxxxxx
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>
>
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