I was able to work on this issue again. I downloaded the latest builds, reset
my JBoss environment and with the correct set of jars, I do not see any
issues with the multithreading when I use the Locked utility. It was a
mistmatch of versions that caused the earlier problem.
I do however see this error in the logs after I finish entering a node
occasionally. This does not prevent me from adding nodes.
11:18:44,653 INFO [STDOUT] 11:18:44,653 ERROR [ObservationDispatcher]
Synchronous EventConsumer threw exception.
java.lang.NullPointerException
at
org.apache.jackrabbit.core.query.lucene.NodeIndexer.createDoc(NodeIndexer.java:141)
at
org.apache.jackrabbit.core.query.lucene.NodeIndexer.createDocument(NodeIndexer.java:115)
at
org.apache.jackrabbit.core.query.lucene.SearchIndex.createDocument(SearchIndex.java:475)
at
org.apache.jackrabbit.core.query.lucene.SearchIndex$2.next(SearchIndex.java:318)
at
org.apache.jackrabbit.core.query.lucene.MultiIndex.update(MultiIndex.java:321)
at
org.apache.jackrabbit.core.query.lucene.SearchIndex.updateNodes(SearchIndex.java:306)
at
org.apache.jackrabbit.core.SearchManager.onEvent(SearchManager.java:451)
This seems to be an issue already discussed elsewhere. I will refer to the
same.
Marcel Reutegger wrote:
>
> vijay s wrote:
>> Problem:
>>
>> I am able to get my application working with the Locked utility class,
>> but I
>> believe the locking of the folder to add content is causing some issues
>> when
>> I try to "concurrently" add many nodes to a single folder.
>>
>> Jackrabbit throws a random ItemNotFoundException after I add about 400
>> nodes
>> concurrently in 20 threads -->
>> (javax.jcr.ItemNotFoundException:
>> a3214cbe-2a89-4550-8b1b-2b76cce821c0/{http://www.jcp.org/jcr/1.0}lockOwner).
>>
>> Once such an error happens in one of my threads, the rest of the threads
>> get
>> stuck in some form of a deadlock and my server crashes. The crashes
>> become
>> more frequent and detrimental as I increase the number of concurrent
>> threds.
>
> this is strange. our test cases for the utility use 100 concurrent threads
> and
> run without any errors. See:
> http://svn.apache.org/repos/asf/jackrabbit/tags/1.2.1/jackrabbit-core/src/test/java/org/apache/jackrabbit/core/LockTest.java
>
>> Questions:
>>
>> 1) Is there any alternative to this locking procedure to add child nodes
>> to
>> a node. Do we "have" to lock a parent node to add child nodes ?
>
> No, as of version 1.2.1 jackrabbit is able to handle concurrent addNode()
> from
> multiple sessions without the need to lock the parent node. See:
> http://issues.apache.org/jira/browse/JCR-584
>
>> I have found
>> that I get better reliability when I do not use the Locked utility class,
>> but just synchronize the code in a way where only one session can add
>> nodes
>> to a particular folder. I really do not want to single thread the
>> application. Any recommendations on a better approach will be really
>> appreciated. Any insights on this particular cause of the
>> ItemNotFoundException will also be helpful.
>
> See my comments inline
>
>> Code Snippet:
>>
>> public void addContent(final String nodeId, final String nodeType, final
>> Map properties) {
>> System.out.println("Adding project "+nodeId);
>
> Where do you get the session from? What does the parameter do?
>
>> Session session = getSession(true);
>> try {
>> final Node folder =
>> session.getRootNode().getNode("assemblies");
>> Node child = null;
>> if (!folder.hasNode(nodeId)) {
>> Object retChild = new Locked() {
>> protected Object run(Node folder) throws
>> RepositoryException {
>> Node c = folder.addNode(nodeId,
>> nodeType != null ? nodeType
>> :
>> "nt:unstructured");
>>
>> c.addMixin("mix:versionable");
>> for (Object key :
>> properties.keySet()) {
>>
>> c.setProperty((String) key, (String) properties
>>
>> .get(key));
>> }
>>
>> folder.save();
>> return c;
>> }
>> }.with(folder, false,100000);
>> if(retChild==Locked.TIMED_OUT){
>> throw new RuntimeException("Exception
>> occured when adding a node.
>> Please try again");
>> } else {
>> child = (Node)retChild;
>> }
>
> This call is not needed. There shouldn't be any changes on the session at
> this
> point.
>
>> session.save();
>> child = folder.getNode(nodeId);
>> System.out.println("Added project
>> "+child.getPath()+" successfully");
>> }
>> } catch (InterruptedException ex) {
>> throw new RuntimeException(ex);
>> } catch (RepositoryException ex) {
>> throw convertJCRAccessException(ex);
>> } finally {
>> session.logout();
>> }
>> }
>
> Otherwise the code looks ok to me.
>
> Are you able to get the stacktrace of the root cause? The one that shows
> where
> the ItemNotFoundException is thrown.
>
> regards
> marcel
>
>> Exception Snippet:
>> org.springframework.dao.DataRetrievalFailureException: Item not found;
>> nested exception is javax.jcr.ItemNotFoundException:
>> a3214cbe-2a89-4550-8b1b-2b76cce821c0/{http://www.jcp.org/jcr/1.0}lockOwner
>> at
>> org.springmodules.jcr.SessionFactoryUtils.translateException(SessionFactoryUtils.java:197)
>> at
>> org.springmodules.jcr.JcrAccessor.convertJcrAccessException(JcrAccessor.java:58)
>> at
>> org.springmodules.jcr.support.JcrDaoSupport.convertJCRAccessException(JcrDaoSupport.java:117)
>> at ContentDaoImpl.addContent(ContentDaoImpl.java:44)
>> at ContentServiceImpl.addNewProject(ContentServiceImpl.java:51)
>>
>
>
>
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