On 04/05/2010 14:10, Mark Shifman wrote: > > On 05/03/2010 02:53 PM, Pid wrote: >> On 03/05/2010 18:30, Mark Shifman wrote: >>> >>> On 05/03/2010 12:48 PM, Pid wrote: >>>> On 03/05/2010 17:15, Mark Shifman wrote: >>>>> I have a web app running under tomcat-6.0.26 with >>>>> JreMemoryLeakPreventionListener, java jdk1.6.0_18. >>>>> >>>>> Using jmap -histo pid, I can watch >>>>> com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl, etc increase in >>>>> number >>>>> after running my unmarshal action, followed by undeploy and redeploy. >>>>> Find Leaks in the manager also finds leaks. >> >> Do you see log messages referring to potential leaks in the catalina.out >> log (assuming you're on a unix variant)? >> >> If so, can you post them please? > > There are no messages in catalia.out concerning leaks (I am using Linux > 2.6.18-92.1.22.el5) > I also got rid of timeBetweenEvictionRunsMillis in datasource since it causes > a leaky TimerThread). > >> >> What does the manager 'find leaks' command report exactly? > ... > leak (use a profiler to confirm): > /yp_results
There are some useful commands in the JDK which may help track down
exactly which class is causing the problem.
jmap -histo <pid>
(and other jmap subcommands)
If you take a snapshot periodically, esp after reload cycles you may be
able to see which classes are increasing in number.
If you can get a VisualVM working, or connect a JConsole to the remote
VM you may be able to poke around and see which classes aren't being
garbage collected.
> My webapp is named yp_results.
>>
>>>> After a few undeploy/redeploy cycles does the number of
>>>> WebappClassLoader's also increase?
>>>
>>> Yes it increases 1 for each undeploy/redeploy cycle.
>>
>>> snip... <
>>
>>>> Maybe.
>>>>
>>>>> JAXBContext.newInstance() can take a ClassLoader argument. Is there some
>>>>> ClassLoader I should be using that will get around this?
>>
>> OK, so I've looked at JAXBContext (and JAXBContextImpl) and it doesn't
>> (after quick read through) look like it's storing the classloader
>> argument anywhere during the newInstance call, which is the usual source
>> of leaks.
>>>> Where is the jar with the above code, in a webapp?
>>> The code above in in the war for the web app in a class in
>>> WEB-INF/classes/org/blablabla
>>>
>>> It is called via a class that looks like this:
>>>
>>> public class JAXBMascot {
>>> protected static Log log = LogFactory.getLog(JAXBMascot.class);
>>> private XMLEventReader reader;
>>> private Unmarshaller u =
>>> JAXBContextMascot.INSTANCE.createUnmarshaller();
>>
>> You're setting the XMLEventReader, Unmarshaller & InputStream as
>> instance field values, rather than completing the parsing in the
>> getInstance() method?
> I have really big xmls to unmarshall so I am using streaming them in and
> unmarshalling the elements I want
> and then insert into my database. I need the reader to see where I am and
> then the umarshaller
I'll have a look at the code below a bit later, am pushed for time right
now.
p
> I didn't show the all the methods of JAXBMascot but here is workhorse:
> public <T> T getNextElement(String theElement, String elementAfter,
> Class <T>clazz) {
> String elname = "";
> T h = null;
> try {
> while(reader.hasNext()){
> if(reader.peek().isStartElement()){
> elname =
> reader.peek().asStartElement().getName().getLocalPart();
> if(elname.equals(theElement)){
> h= u.unmarshal(reader, clazz).getValue();
> return h;
> }
> } else if(reader.peek().isEndElement()){
> elname =
> reader.peek().asEndElement().getName().getLocalPart();
> if(elname.equals(elementAfter)){
> return h;
> }
> }
>
> reader.nextEvent();
> }
> } catch (XMLStreamException e) {
> throw new RuntimeException(e);
> } catch (JAXBException e) {
> throw new RuntimeException(e);
> }
> return h;
> }
>
> It also has a close method to clean up after I have gotten all the elements.
> public void close(){
> try {
> reader.close();
> } catch (XMLStreamException e) {
> //quietly
> }
> IOUtils.closeQuietly(jxb_in);
> u=null;
> }
> I don't think I am leaving any stuff hanging around but memory leaks are very
> sneaky.
> mas
>>
>> This looks a bit odd to me, but I don't know what the rest of the
>> instance does...
>>
>>
>> p
>>
>>> private InputStream jxb_in;
>>>
>>> public static JAXBMascot getInstance(InputStream in) {
>>> JAXBMascot m = new JAXBMascot();
>>> try {
>>> m.setJxb_in(in);
>>>
>>> m.setReader(XMLInputFactory.newInstance().createXMLEventReader(in));
>>> } catch (Exception e) {
>>> log.fatal("error getting JAXBMascot instance");
>>> IOUtils.closeQuietly(in);
>>> throw new RuntimeException(e);
>>> }
>>>
>>> return m;
>>> }
>>> ....
>>> }
>>>
>>> This is also in the webapp in WEB-INF/classes/org/blablabla
>>
>>
>>
>
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