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From Kevin Sutter <kwsut...@gmail.com>
Subject Re: memory leak? - simple question
Date Thu, 14 Jan 2010 23:32:04 GMT
Hi Kurt,
I have not run a profiler to verify the memory leak, but I think I found the
problem...

Although you thought you were running the PCEnhancer during build time, it
was not being performed.  When I looked at the Tomcat log with the original
jar file, the following message was logged which indicates you were falling
back to the "not ready for production" subclassing support:

1844  juddiDatabase  INFO   [http-8080-1] openjpa.Enhance - Creating
subclass for "[class org.apache.juddi.AuthToken]". This means that your
application will be  less efficient and will consume more memory than it
would if you ran the OpenJPA enhancer. Additionally, lazy loading will not
be available for one-to-one and many-to-one persistent attributes in types
using field access; they will be loaded eagerly instead.

I made a few changes to your pom.xml and the "core" module to get the
enhancement to work and I believe the memory leak has went away.  Like I
said, I did not run a profiler, but I added a "finalize" method to your
AuthToken class and I now see that these entities are getting GC'd.

One thing I would do is add the following property to your persistence.xml.

<property name="openjpa.RuntimeUnenhancedClasses" value="warn"/>

This property will produce the following warning if you accidentally fall
into this subclassing support.  We turn this off by default when running
within WebSphere since we really don't want customers to accidentally use
this subclassing.  And, we have turned this off for 1.3.x and trunk due to
the various problems associated with it.  Unfortunately, the 1.2.x branch is
kind of stuck with it...

1688  juddiDatabase  WARN   [http-8080-1] openjpa.Enhance - This
configuration disallows runtime optimization, but the following listed types
were not enhanced at build time or at class load time with a javaagent:
"[class org.apache.juddi.AuthToken]".

And, of course, your webservice no longer works either.  You will get an
HTTP Status 500 error with an error message and call stack that further
explains the error.

To get the maven plugin to work properly...  I made several changes, so
hopefully I remember everything...

o  The number one thing is that the openjpa:enhance goal doesn't seem to get
automatically invoked when you compile.  I have no idea why, but that
doesn't seem to work.

o  You have to make your persistence.xml file available to the "core"
module.  For my testing, I just created a new directory in the "core" module
called "\openjpa-leak\core\src\main\resources\META-INF\persistence.xml".
This will automatically get copied over to "target" and then the
openjpa:enhance goal will find it.

o  How you want to make your persistence.xml file available to both your
"core" module and the "leak-war" module is up to you...  :-)

o  I added a dependency in your core\pom.xml file for the 1.2.1 openjpa.
The documentation [1] says it will default to 1.2.0, if none is specified.

            <dependencies>
                <dependency>
                    <groupId>org.apache.openjpa</groupId>
                    <artifactId>openjpa</artifactId>
                    <version>1.2.1</version>
                </dependency>
            </dependencies>

o  Your plugin properties don't seem to be specified correctly, at least
according to the documentation, but I didn't touch them and things still
seemed to work (once I got around the other problems).

o  I also changed where to find the entities to enhance since this pom.xml
still specified the "model" directory.  There also seems to be confusion as
to whether to specify <classes> or <includes>.  I went with <includes> since
that's what the example showed.

o  It's very easy to see if the enhancement process worked or not since the
size of your entity classes increases by a few thousand bytes.  And, with
the extra property above, this will prevent you from accidentally using the
unenhanced version.

Hope this helps!  Let me know if this gets you around the memory leak.

Kevin

[1]  http://mojo.codehaus.org/openjpa-maven-plugin/usage.html



On Thu, Jan 14, 2010 at 2:12 PM, Kurt T Stam <kurt.stam@gmail.com> wrote:

> 1. Cool that you got it running :)
>
> 2. I just ran with openjpa 1.2.2.SNAPSHOT and still see an accumulation of
> AuthToken objects.
>
> --K
>
>
> Kevin Sutter wrote:
>
>> Hey, this wasn't so difficult...  :-)  Maybe I can still learn new
>> things...  I have Tomcat up and running and I can get your app running.
>>
>> On Thu, Jan 14, 2010 at 1:46 PM, Kevin Sutter <kwsutter@gmail.com> wrote:
>>
>>
>>
>>> Hi Kurt,
>>> These instructions, of course, assume that I know something about Tomcat.
>>> This would not be a good assumption...  :-)  If you really want me to see
>>> this in action, I will need more information on how to start Tomcat and
>>> how
>>> to load applications.  In the mean time, a trace log of OpenJPA would be
>>> an
>>> excellent start.
>>>
>>> Thanks!
>>> Kevin
>>>
>>>
>>> On Thu, Jan 14, 2010 at 11:30 AM, Kurt T Stam <kurt.stam@gmail.com>
>>> wrote:
>>>
>>>
>>>
>>>> Hi Kevin,
>>>>
>>>> I tried adding the javaagent stuff, and it still ends up leaking. I
>>>> extracted the code into a tiny
>>>> war with just one servlet which persist the authToken. The build creates
>>>> a
>>>> Tomcat distro backed by a
>>>> derby database. You can download it from:
>>>>
>>>> http://people.apache.org/~kstam/leak.tgz<http://people.apache.org/%7Ekstam/leak.tgz>
>>>> <http://people.apache.org/%7Ekstam/leak.tgz>
>>>>
>>>>
>>>> You can build it with: mvn install, you can find the final tomcat in
>>>> tomcat/target/tomcat-1.0.SNAPSHOT.zip
>>>>
>>>> or if you don't want to build it:
>>>> http://people.apache.org/~kstam/tomcat-1.0.SNAPSHOT.zip<http://people.apache.org/%7Ekstam/tomcat-1.0.SNAPSHOT.zip>
>>>> <http://people.apache.org/%7Ekstam/tomcat-1.0.SNAPSHOT.zip>
>>>>
>>>>
>>>> After you bring up tomcat it persistent an authToken when you hit
>>>> http://localhost:8080/leak/test
>>>>
>>>> In the profiler I see an org.apache.juddi.AuthToken left behind for each
>>>> request.
>>>>
>>>> Hopefully this little example will pinpoint what's going on.
>>>>
>>>> Thx Kev for sticking with me :)
>>>>
>>>> --Kurt
>>>>
>>>>
>>>>
>>>> Kevin Sutter wrote:
>>>>
>>>>
>>>>
>>>>> Hi Kurt,
>>>>> Since you have the environment to reproduce this, could you run with
>>>>> the
>>>>> OpenJPA trace enabled?  I'm not even sure what I'm looking for at this
>>>>> point.  :-)  But, maybe there's some tracing that would point us in the
>>>>> right direction.
>>>>>
>>>>> <property name="openjpa.Log" value="DefaultLevel=TRACE"/>
>>>>>
>>>>> We have been always been on the watch for memory leaks, so this one is
>>>>> puzzling.  You did mention blocked threads as well.  At this point, you
>>>>> are
>>>>> probably hitting blocked threads due to the GC and Memory problems.
>>>>>  But,
>>>>> we
>>>>> did recently resolve some locking situations [1] in our
>>>>> MetaDataRepository
>>>>> that could affect scaling (under extreme load).  This was resolved in
>>>>> the
>>>>> 1.2.x SNAPSHOT drivers (Mike is currently pushing for a 1.2.2 release,
>>>>> so
>>>>> that should be coming soon).
>>>>>
>>>>> Does your WebService version of the problem use EntityManager
>>>>> transactions,
>>>>> or is the transaction service coming from Tomcat?  And, does your
>>>>> WebService
>>>>> version also do the em.clear() and em.close()?  Basically, are you
>>>>> using
>>>>> application-managed or container-managed persistence while running as
a
>>>>> WebService?
>>>>>
>>>>> I'm very interested in helping to resolve this issue.  Like I
>>>>> mentioned,
>>>>> we
>>>>> do a lot of memory leakage and scalability testing of the OpenJPA
>>>>> solution
>>>>> and we're not aware of anything.  Although there is always the
>>>>> possibility
>>>>> that something was resolved in the 1.2.x branch after the 1.2.1 release
>>>>> that
>>>>> I'm not remembering...
>>>>>
>>>>> Thanks for your help,
>>>>> Kevin
>>>>>
>>>>> [1]  https://issues.apache.org/jira/browse/OPENJPA-250
>>>>>
>>>>> On Wed, Jan 13, 2010 at 9:27 PM, Kurt T Stam <kurt.stam@gmail.com>
>>>>> wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> Thanks Kevin,
>>>>>>
>>>>>> We're enhancing at build time:
>>>>>>
>>>>>>
>>>>>>
>>>>>> http://svn.apache.org/repos/asf/webservices/juddi/trunk/juddi-core/pom.xml
>>>>>>
>>>>>> Yeah we've been running load tests and things are nice and stable
with
>>>>>> Hibernate but with Openjpa we see increasing memory use, blocking
>>>>>> threads
>>>>>> and then an OOM. http://issues.apache.org/jira/browse/JUDDI-267.
Our
>>>>>> preference would be to ship with openjpa by default; but our build
>>>>>> supports
>>>>>> both hibernate and openjpa.
>>>>>>
>>>>>> And yes we use openjpa 1.2.1 (latest stable version).
>>>>>>
>>>>>> --Kurt
>>>>>>
>>>>>>
>>>>>> Kevin Sutter wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> Interesting detective work, Kurt.  Thanks.
>>>>>>>
>>>>>>> Why the WebService version of the app would behave differently
as far
>>>>>>> as
>>>>>>> GC
>>>>>>> is concerned is a mystery.  And, you said that plugging in Hibernate
>>>>>>> into
>>>>>>> this scenario, everything works okay?  Very confusing.
>>>>>>>
>>>>>>> How are you performing the Entity enhancement processing?  Are
you
>>>>>>> pre-enhancing via your build process?  Or, are you using the
>>>>>>> -javaagent
>>>>>>> mechanism?  Or, are you falling back to the subclassing support
>>>>>>> within
>>>>>>> OpenJPA?  (See [1] for more information on these questions in
case
>>>>>>> they
>>>>>>> don't make sense.)
>>>>>>>
>>>>>>> This would be one area that is different between Hibernate and
>>>>>>> OpenJPA
>>>>>>> --
>>>>>>> enhancement processing.
>>>>>>>
>>>>>>> In the Tomcat environment, you may be falling back to the subclassing
>>>>>>> support (which we do not recommend) and hitting a memory leak
with
>>>>>>> that.
>>>>>>>
>>>>>>> You said OpenJPA 1.2.x, right?
>>>>>>>
>>>>>>> Just a couple of thoughts on the subject...
>>>>>>> Kevin
>>>>>>>
>>>>>>> [1]
>>>>>>>
>>>>>>>
>>>>>>> http://webspherepersistence.blogspot.com/2009/02/openjpa-enhancement.html
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Wed, Jan 13, 2010 at 4:25 PM, Kurt T Stam <kurt.stam@gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> The same code executed straight from a java client (inVM)
shows no
>>>>>>>> memory
>>>>>>>> leak.
>>>>>>>>
>>>>>>>> So is the fact that it is WebService significant then? What
else can
>>>>>>>> be
>>>>>>>> different? I think one thread remains up, and somehow this
causes
>>>>>>>> openjpa
>>>>>>>> not being able to clean up after itself. What can I do to
debug this
>>>>>>>> more? I
>>>>>>>> can actually see in the profiler that the objects are allocated
by
>>>>>>>> the
>>>>>>>> WebService, but why aren't they cleaned up?
>>>>>>>>
>>>>>>>> Thx,
>>>>>>>>
>>>>>>>>
>>>>>>>> --Kurt
>>>>>>>>
>>>>>>>>
>>>>>>>> Kurt T Stam wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> Thanks Kevin, thanks for your response.
>>>>>>>>>
>>>>>>>>> I just replaced the static call by:
>>>>>>>>>
>>>>>>>>>            apiAuthToken = new org.uddi.api_v3.AuthToken();
>>>>>>>>>            apiAuthToken.setAuthInfo(modelAuthToken.getAuthToken());
>>>>>>>>>            //MappingModelToApi.mapAuthToken(modelAuthToken,
>>>>>>>>> apiAuthToken);
>>>>>>>>>
>>>>>>>>> which did not make a difference.
>>>>>>>>>
>>>>>>>>> I'm wondering if the fact that my class is a webservice
makes a
>>>>>>>>> difference. I'll try extracting it into
>>>>>>>>> a regular class with a main method and profile that.
At least I
>>>>>>>>> know
>>>>>>>>> that
>>>>>>>>> I didn't forget something
>>>>>>>>> completely obvious..
>>>>>>>>>
>>>>>>>>> --Kurt
>>>>>>>>>
>>>>>>>>> Kevin Sutter wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> Kurt,
>>>>>>>>>> I agree that this is very common usage of the JPA
programming
>>>>>>>>>> model.
>>>>>>>>>>  And,
>>>>>>>>>> we are not aware of any memory leaks.  About the
only thing that
>>>>>>>>>> jumps
>>>>>>>>>> out
>>>>>>>>>> at me is the following two lines:
>>>>>>>>>>
>>>>>>>>>>             apiAuthToken = new org.uddi.api_v3.AuthToken();
>>>>>>>>>>             MappingModelToApi.mapAuthToken(modelAuthToken,
>>>>>>>>>> apiAuthToken);
>>>>>>>>>>
>>>>>>>>>> What do these do?  Can you comment these out and
see if the memory
>>>>>>>>>> leak
>>>>>>>>>> still exists?  Since you are passing the modelAuthToken
into this
>>>>>>>>>> method,
>>>>>>>>>> I
>>>>>>>>>> don't know what it's doing with the reference and
could it be
>>>>>>>>>> holding
>>>>>>>>>> onto
>>>>>>>>>> something to prevent the GC from cleaning up?
>>>>>>>>>>
>>>>>>>>>> The rest of your example seems very straight forward
with creating
>>>>>>>>>> and
>>>>>>>>>> persisting objects.
>>>>>>>>>>
>>>>>>>>>> Kevin
>>>>>>>>>>
>>>>>>>>>> On Wed, Jan 13, 2010 at 2:09 PM, Rick Curtis <curtisr7@gmail.com>
>>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>> If you change the 1000 to something like 1000000...
does your
>>>>>>>>>>> application
>>>>>>>>>>> go
>>>>>>>>>>> OOM? Are you running in a JSE environment? What
is
>>>>>>>>>>> PersistenceManager?
>>>>>>>>>>>
>>>>>>>>>>> On Wed, Jan 13, 2010 at 2:05 PM, Kurt T Stam
<
>>>>>>>>>>> kurt.stam@gmail.com>
>>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> BTW I'm running with the cache off
>>>>>>>>>>>>
>>>>>>>>>>>> <property name="openjpa.DataCache" value="false"/>
>>>>>>>>>>>>
>>>>>>>>>>>> (that turns it off right?)
>>>>>>>>>>>>
>>>>>>>>>>>> --Kurt
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Kurt T Stam wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>> Hi guys,
>>>>>>>>>>>>>
>>>>>>>>>>>>> [DESCRIPTION] The code below inserts
a 1000 records in the
>>>>>>>>>>>>> database.
>>>>>>>>>>>>>
>>>>>>>>>>>>> for (int i=1; i<1000; i++) {
>>>>>>>>>>>>>       EntityManager em = PersistenceManager.getEntityManager();
>>>>>>>>>>>>>       EntityTransaction tx = em.getTransaction();
>>>>>>>>>>>>>       try {
>>>>>>>>>>>>>           tx.begin();
>>>>>>>>>>>>>               // Generate auth token
and store it!
>>>>>>>>>>>>>           String authInfo = AUTH_TOKEN_PREFIX
+
>>>>>>>>>>>>> UUID.randomUUID();
>>>>>>>>>>>>>           org.apache.juddi.model.AuthToken
modelAuthToken = new
>>>>>>>>>>>>> org.apache.juddi.model.AuthToken();
>>>>>>>>>>>>>           if (authInfo != null) {
>>>>>>>>>>>>>               modelAuthToken.setAuthToken(authInfo);
>>>>>>>>>>>>>               modelAuthToken.setCreated(new
Date());
>>>>>>>>>>>>>               modelAuthToken.setLastUsed(new
Date());
>>>>>>>>>>>>>               modelAuthToken.setAuthorizedName(publisherId);
>>>>>>>>>>>>>               modelAuthToken.setNumberOfUses(0);
>>>>>>>>>>>>>               modelAuthToken.setTokenState(AUTHTOKEN_ACTIVE);
>>>>>>>>>>>>>                 em.persist(modelAuthToken);
>>>>>>>>>>>>>           }
>>>>>>>>>>>>>             apiAuthToken = new org.uddi.api_v3.AuthToken();
>>>>>>>>>>>>>             MappingModelToApi.mapAuthToken(modelAuthToken,
>>>>>>>>>>>>> apiAuthToken);
>>>>>>>>>>>>>             tx.commit();
>>>>>>>>>>>>>                     } finally {
>>>>>>>>>>>>>           if (tx.isActive()) {
>>>>>>>>>>>>>               tx.rollback();
>>>>>>>>>>>>>           }
>>>>>>>>>>>>>           em.clear();
>>>>>>>>>>>>>           em.close();
>>>>>>>>>>>>>       }
>>>>>>>>>>>>>   }
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> [ISSUE]
>>>>>>>>>>>>> After it leaving this code I end up with
a 1000
>>>>>>>>>>>>> org.apache.juddi.model.AuthToken objects
in memory. I've been
>>>>>>>>>>>>> using
>>>>>>>>>>>>> the
>>>>>>>>>>>>> profiler, and these objects cannot be
garbage collected.
>>>>>>>>>>>>>
>>>>>>>>>>>>> This seems to be pretty the most common
use case of using an
>>>>>>>>>>>>> OR-mapping
>>>>>>>>>>>>> tool, so I find it hard to believe openjpa
has a memory leak
>>>>>>>>>>>>> here.
>>>>>>>>>>>>> Does
>>>>>>>>>>>>> anyone see what I'm doing wrong? Or can
someone point me to an
>>>>>>>>>>>>> example
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>> that
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> does not exhibit this behavior? BTW same
code using hibernate
>>>>>>>>>>>> does
>>>>>>>>>>>> not
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>> accumulate these objects.
>>>>>>>>>>>>>
>>>>>>>>>>>>> We're using openjpa 1.2.1.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Thx,
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Kurt
>>>>>>>>>>>>>
>>>>>>>>>>>>> Apache jUDDI.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>> Thanks,
>>>>>>>>>>> Rick
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>>
>
>

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