Failed to lazily initialize a collection - no session or session was closed

[Steve Loft]

I have implemented a 'long running task' in my plugin. It manipulates pages - deleting, moving, creating, so I understand that I need to wrap my long running task in a transaction?

I have followed the first example on this page: https://developer.atlassian.com/display/CONFDEV/Hibernate+Sessions+and+Transaction+Management+Guidelines

But I get the following error:

net.sf.hibernate.LazyInitializationException: Failed to lazily initialize a collection - no session or session was closed

at net.sf.hibernate.collection.PersistentCollection.initialize(PersistentCollection.java:209)

at net.sf.hibernate.collection.PersistentCollection.read(PersistentCollection.java:71)

at net.sf.hibernate.collection.Bag.iterator(Bag.java:256)

at com.fujitsu.VME.confluence.plugins.PageControl.PublishLongRunningTask$1.doInTransaction(PublishLongRunningTask.java:138)

My code looks like this:

@Override
	protected void runInternal() {
		
		Object result = transactionTemplate.execute(new TransactionCallback()
		{
		    @Override
		    public Object doInTransaction()
		    {
		    	
				try {					
					Space devSpace = page.getSpace();

					Page homePage = devSpace.getHomePage();

					List<Page> children = homePage.getChildren();

					for (Page child : children) {
						// Do stuff with page
					}
				} catch (Exception e) {
					progress.setStatus("Publish failed: " + e.getMessage());
					progress.setCompletedSuccessfully(false);
				} finally {
					progress.setPercentage(100);
				}		 
		        return null;
		    }
		});
	}

I am getting 'page' and 'transactionTemplate' via Spring injection.

The exception occurs at the line 'for (Page child : children) {' - could someone please tell me what I might be doing wrong and how I fix it?

Steve

[Joe Clark · Accepted solution]

Hi Steve,

The Confluence 'content' objects (like pages, blogs, comments and attachments) are hibernate objects and have a transaction affinity. In other words, you cannot read a Confluence object from the database in one transaction and then reference a property on it in another transaction - this appears to be what you are doing with the 'page' object that you are accessing.

Instead of passing the page object into your transaction callback, pass in the unique ID of the page and then re-retrieve the page object within your new transaction using the PageManager.

eg.

@Override
    protected void runInternal()
    {
        final long pageId = page.getId();

        Object result = transactionTemplate.execute(new TransactionCallback()
        {
            @Override
            public Object doInTransaction()
            {
                try
                {
                    Page p = pageManager.getPage(pageId);
                    
                    Space devSpace = p.getSpace();

                    Page homePage = devSpace.getHomePage();

                    List<Page> children = homePage.getChildren();

                    for (Page child : children)
                    {
                        // Do stuff with page
                    }
                } 
                catch (Exception e)
                {
                    progress.setStatus("Publish failed: " + e.getMessage());
                    progress.setCompletedSuccessfully(false);
                } 
                finally
                {
                    progress.setPercentage(100);
                }
                return null;
            }
        });
    }

[Steve Loft]

Thanks, Joseph, that fixed it.

Steve