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
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 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
>
>
>
--
Mark Shifman MD. Ph.D.
Yale Center for Medical Informatics
Phone (203)737-5219
mark.shif...@yale.edu
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