Re: [aspectj-users] Bytecode Caching in AspectJ

[Andy Clement <andrew.clement@xxxxxxxxx>]

Hi,

AspectJ attempts to read many system properties to configure its
behaviour.  Normally the property read is guarded by a try...catch so
that if you haven't given it permissions then it will continue with a
default behaviour.  The line you are having trouble with only had a
try...catch added recently.  The fix for you would be to move to a
more recent AspectJ.  A late 1.6.X or 1.7.0.


> org.aspectj.matcher.jar:
>
>   I have read that org.aspectj.matcher.jar is used to match only classes
> that is needed for weaving. Please let me know its role still more in depth
> and how can enable it  in our programming .

The AspectJ weaver includes two parts: (a) the matching code to
determine what code matches what pointcut (b) the weaver that makes
the code modifications.
When working in a framework like Spring, sometimes it only wants the
matching logic as it implements the weaving in a different way
(proxies).  The org.aspectj.matcher jar contains only the code
required to match.  If you are using real aspects (code or annotation
style) you really need to use the weaver jar.  If you are in a spring
environment and using proxies you can possibly just use the matcher
jar.  Why do you think you dont want the weaver jar? Is it because of
the exception you were hitting?

cheers,
Andy

On 7 August 2012 07:12, Jeevitha Muthusamy <mail2jeevithamk@xxxxxxxxx> wrote:
>
> Hi Andy,
>
> In Websphere,when aspects are enabled, the following exception is thrown.
>
> java.security.AccessControlException: Access denied
> (java.util.PropertyPermission aj.weaving.verbose read)
> at
> java.security.AccessControlException.<init>(AccessControlException.java:62)
> at java.security.AccessController.checkPermission(AccessController.java:68)
> at java.lang.SecurityManager.checkPermission(SecurityManager.java:533)
> at java.lang.SecurityManager.checkPropertyAccess(SecurityManager.java:1286)
> at java.lang.System.getProperty(System.java:379)
> at java.lang.System.getProperty(System.java:367)
> at java.lang.Boolean.getBoolean(Boolean.java:233)
> at
> org.aspectj.weaver.tools.WeavingAdaptor.getVerbose(WeavingAdaptor.java:154)
> at org.aspectj.weaver.tools.WeavingAdaptor.<init>(WeavingAdaptor.java:91)
> at
> org.aspectj.weaver.loadtime.ClassLoaderWeavingAdaptor.<init>(ClassLoaderWeavingAdaptor.java:83)
> at org.aspectj.weaver.loadtime.Aj$WeaverContainer.getWeaver(Aj.java:115)
> at org.aspectj.weaver.loadtime.Aj.preProcess(Aj.java:73)
> at
> org.aspectj.weaver.loadtime.ClassPreProcessorAgentAdapter.transform(ClassPreProcessorAgentAdapter.java:55)
> .............
>
> What could be the reason for this? How can we resolve this?
>
>
> org.aspectj.matcher.jar:
>
>   I have read that org.aspectj.matcher.jar is used to match only classes
> that is needed for weaving.
>   Please let me know its role still more in depth and how can enable it  in
> our programming .
>
>
> Thanks,
> Jeevitha
>
>
> On Tue, Jul 31, 2012 at 6:41 AM, Andy Clement <andrew.clement@xxxxxxxxx>
> wrote:
>>
>> Oh and the best way to learn about what is in releases beyond 1.5.4 is
>> to skim the readmes.  They aren't very verbose documents:
>>
>> http://www.eclipse.org/aspectj/doc/released/README-160.html
>> http://www.eclipse.org/aspectj/doc/released/README-161.html
>> http://www.eclipse.org/aspectj/doc/released/README-162.html
>> etc to README-1612
>> http://www.eclipse.org/aspectj/doc/released/README-170.html
>>
>> In 1.6.8 there was a major performance boost due to an internals
>> rewrite.  And actually if you are seeing serialversionuid problems in
>> 1.5.4 that may not contain all the fixes for the -XaddSerialVersionUID
>> feature.  I would recommend upgrading if you can.
>>
>> Andy
>>
>>
>> On 30 July 2012 18:08, Andy Clement <andrew.clement@xxxxxxxxx> wrote:
>> > IIRC you shouldn't have to turn permissions on to get it to run.
>> > However some of the configurable behaviour won't be configurable if
>> > you don't enable some permissions.  For example AspectJ needs to be
>> > able to access system properties to check some configuration settings.
>> >
>> > What precise permission is it complaining about? (and where?)
>> >
>> > cheers,
>> > Andy
>> >
>> > On 29 July 2012 23:07, Jeevitha Muthusamy <mail2jeevithamk@xxxxxxxxx>
>> > wrote:
>> >> Thanks Andy !!
>> >>
>> >> We have faced java security permission issue while enabling Aspect code
>> >> in
>> >> Websphere Application server.
>> >>
>> >> Is it mandatory to set java security  permissions to enable aspects for
>> >> Websphere or for all application serversr??
>> >>
>> >> Please let me know some aspectj features since 1.5.4,  that is
>> >> applicable
>> >> and effective in Java 6.
>> >>
>> >> Thanks,
>> >> Jeevitha
>> >>
>> >>
>> >>
>> >> On Sat, Jul 28, 2012 at 4:10 AM, Andy Clement
>> >> <andrew.clement@xxxxxxxxx>
>> >> wrote:
>> >>>
>> >>> On 23 July 2012 01:54, Jeevitha Muthusamy <mail2jeevithamk@xxxxxxxxx>
>> >>> wrote:
>> >>> >    May I know what is Bytecode Caching in AspectJ1.7 and its
>> >>> > benefits??
>> >>>
>> >>> The caching is currently best described here:
>> >>> https://bugs.eclipse.org/bugs/show_bug.cgi?id=367673
>> >>>
>> >>> It is a per classloader cache of woven bytecode that avoids re-weaving
>> >>> on subsequent restarts.
>> >>>
>> >>> >    And when caching is enabled, what exactly is cached??
>> >>>
>> >>> Per the readme and that bug, the caching is enabled when you turn on
>> >>> the system property:
>> >>>  -Daj.weaving.cache.enabled=true
>> >>>
>> >>> The woven bytecode is cached on a per classloader basis.  On a
>> >>> subsequent JVM restart
>> >>> the cached woven bytecode will be used instead of repeating the
>> >>> weaving
>> >>> process.
>> >>>
>> >>> >   What is the life of Caching? Is it automatically refreshed or is
>> >>> > Static?
>> >>>
>> >>> It is not a super intelligent cache.  If the incoming classes change
>> >>> (in length) then the
>> >>> cache will not be used (as it looks like this class needs reweaving),
>> >>> but changing the
>> >>> set of aspects will not cause reweaving to happen (IIRC).  So this is
>> >>> for a system
>> >>> that is pretty static in terms of aspects but you want faster startup
>> >>> on secondary starts.
>> >>>
>> >>> >   Is there any Memory  limit for Caching? ie. If only to certain
>> >>> > extent
>> >>> > Caching is done or is unlimited??
>> >>>
>> >>> disk space is the limiting factor I believe.
>> >>>
>> >>> >   Is there any constraints(Where this feature is most applicable? )
>> >>> > to
>> >>> > use
>> >>> > this feature?
>> >>>
>> >>> If you have a system where the set of aspects are fixed, this can work
>> >>> well for you.
>> >>> The bug report contains some performance metrics showing you the
>> >>> benefits.
>> >>>
>> >>> >   It will be more helpful, if any use-cases provided or any
>> >>> > documents
>> >>> > regarding this feature!!
>> >>>
>> >>> Unfortunately the only real docs are in the bugzilla, I haven't had
>> >>> the
>> >>> time
>> >>> to integrate anything into the main docs.
>> >>>
>> >>> There are further changes coming into this area on two fronts:
>> >>>
>> >>> - 'asynchronous' caching. It has become apparent that storing entries
>> >>> on the disk in the first start is a bottle-neck and slowing down that
>> >>> initial start.  aynchronous caching will do the storing in a thread.
>> >>> - assume common aspects across all classloaders to give a further
>> >>> boost.  If your system meets this requirement then the cache will
>> >>> actually be consulted during the initial start if it sees two
>> >>> classloaders loading the same class (only one will suffer the weaving
>> >>> cost).  This can make the initial start faster than without caching
>> >>> (as well as speeding up the latter restarts).
>> >>>
>> >>> Andy
>> >>> _______________________________________________
>> >>> aspectj-users mailing list
>> >>> aspectj-users@xxxxxxxxxxx
>> >>> https://dev.eclipse.org/mailman/listinfo/aspectj-users
>> >>
>> >>
>> >>
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