Re: [aspectj-users] Memory consumption problems

[Ashley Williams <ashley.williams@xxxxxx>]

The figures give no indication as to
how steady the memory consumption is since it was just
a snapshot: the worry is that it will
get a lot worse after weeks in production.

I have no idea how aspectj works under
the hood and I can't find much info through google either.
Since we are using LTW, my guess is
that the aspectj class loading interceptor uses bcel to filter the
class files according to our aspects
and in doing so creates the bcel instances below.
Hopefully then, those bcel instances
are just transitory in the LTW process and are immediately
ready for garbage collection when the
new class bytecode is produced.

However this is pure speculation based
on 5 minutes at the bcel website and therefore
would like to find out a little more.
I would definitely recommend at least one prominent
page on this sort of thing at eclipse.org,
since surprises like this, even if it is benign, can
cause panic in organizations at the
early adoption stage for aspectj.

Maybe there is a page and I just haven't
found it yet!

aspectj-users-bounces@xxxxxxxxxxx wrote on 25/07/2008
15:28:43:

> Ashley, from your numbers the memory consumption seems to be pretty
> steady, actually, doesn't it? It certainly isn't growing. so maybe
you
> should use a profiler to figure out where the memory is actually
> consumed. It might just be due to a bug in your implementation. In
> general I am very sure that your assumptions about percflow are
> correct.
> 
> It may also depend on how you measure memory consumption. Up until
now
> I have found no really reliable way to measure memory consumption
in
> Java, even if you manually call the garbage collector etc.
> 
> Eric
> 
> 2008/7/25 Ashley Williams <ashley.williams@xxxxxx>:
> >
> > Hi,
> >
> > We were looking forward to going to production with our profiling
aspect
> > however when we ran our app through jmap we got the chart pasted
below. So
> > it looks like some aspectj objects are responsible for a sizable
share of
> > memory. Without knowing more about them and if they will consume
more memory
> > with time, we can't proceed any further.
> >
> > The aspect we have created contains a stopwatch implementation
and a logger
> > and its cardinality is percflow so we get one per service method
call on our
> > server. I was under the impression though that as soon as the
method call is
> > finished any aspectj resources associated are eligable for garbage
> > collection.
> >
> > I would appreciate it if somebody could shed some light on this.
> >
> > Cheers
> > - Ashley Williams
> >
> > Size                
Count    Class
> >
> > 163466352       2149652 char[]
> > 102393424       609786  byte[]
> > 92017240        2300431 java.lang.String
> > 43706328        114013  java.lang.Object[]
> > 38792736        808182  java.util.HashMap$Entry
> > 32742008        201623  int[]
> > 32662680        269046  java.util.HashMap$Entry[]
> > 31770768        234338  * ConstMethodKlass
> > 26740224        417816  java.util.TreeMap$Entry
> > 24387008        762094  org.aspectj.apache.bcel.classfile.ConstantUtf8
> > 24380640        234338  * MethodKlass
> > 18097728        188518  org.jboss.jms.message.JBossObjectMessage
> > 17139712        267808  java.util.HashMap
> > 16629528        13554   * ConstantPoolKlass
> > 16087896        182817  org.aspectj.apache.bcel.classfile.Method
> > 15182816        172532  org.aspectj.apache.bcel.classfile.Code
> > 14216368        402768  org.aspectj.apache.bcel.classfile.Attribute[]
> > 12472208        82054   java.lang.reflect.Method
> > 11550800        13554   * InstanceKlassKlass
> > 10796824        8196    org.aspectj.apache.bcel.classfile.Constant[]
> > 10261296        199361  * SymbolKlass
> > ---
> >
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> 
> 
> 
> -- 
> Eric Bodden
> Sable Research Group
> McGill University, Montréal, Canada
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