ConcurrentModificationException in RequestContextImpl class

Question

Am currently getting a ConcurrentModificationException thrown by the
notifyRequestCompletionListeners method of the RequestContextImpl
class.
The context is:
A JSP includes two JSP fragments, containing tiled views bound to
primary models and surrounded by jato:context tags, to
enable/disable the display of one or the other.
The observed behavior is as follow:
a) Despite a JSP fragment doesn't need to be displayed (i.e.
beging<>Display method returns false), the associated tiled view is
though instanciated.
How come childs are instantiated though not used ?
I thought JATO instanciates resources only when needed - or is it
maybe because the JSP fragments are statically bound - translation-
time includes ?.
b) While in notifyRequestCompletionListeners method of the
RequestContextImpl class, a requestComplete() triggers the
instantiation of a tiled view, which sets a primary model in its
constructor, which is added to the request context. This triggers
the ConcurrentModificationException. The exception happens when the
tiled view contains a HREF (commenting the HREF out in the
registerChildren method, hides the problem).
How is it that instances are created during the
notifyRequestComplitionListeners method, and why only when the tiled
view contains HREF ?

Answer 1

Jacquess--
I don' t have a lot of time right now, but some comments until I have more
time:
I am getting a ConcurrentModificationException thrown by the
notifyRequestCompletionListeners method.
The context is a JSP including two JSP fragments surrounded
by "content" tags and containing tiled views with HREF childs.
The observed behavior is as follow:
a) Although a JSP fragment is not displayed, i.e. begin<>Display
method returns false, the corresponding tiled view class is though
instantiated.The question is when is it instantiated? I would expect it to be
instantiated on the subsequent request back to the server, but not during
the response/rendering phase (when the content tag comes into play). The
built-in mapRequestParameters() logic is not smart enough to skip mapping
values for registered containers. You may be able to encode a value in the
page that indicates the non-displayed views and avoids registering them for
that request. To do this, would want to use the optional constructor for
the ViewBean that takes a RequestContext:
public class MyViewBean extends ViewBeanBase
public MyViewBean(RequestContext context)
super(PAGE_NAME);
registerChild("text1",TextField.class);
if (context.getRequest().getParameter(TILEDVIEW1_SHOWN)!=null)
registerChild("tiledView1",MyTiledView.class);
registerChild("text2",TextField.class);
Get the idea? This is just a thought, I haven't thought it through
completely. In the future, would could perhaps encode this information
transparently for you and take advantage if it during parameter mapping.
I thought JATO instantiates childs only when needed ?
Is it because the JSP fragments are translation time includes ?
b) While iterating over the request completion listeners in the
notifyRequestCompletionListeners method, a new completion listener is
added, causing the ConcurrentModificationException. The completion
listener, which is the primary model of a tiled view, is added when
registering a child that is a HREF bound to this primary model.
Commenting out the registration of the HREF child in the tiled view
hides the problem.Patient: "Doctor, my arm hurts when I do this."
Doctor: "So don't do that."
Are you saying the registration is happening automatically and unavoidably
as a result of some JATO behavior, or are you intentionally adding a
listener during notification?
Should not all required childs be instantiated before the
notifyRequestCompletionListeners method is called ?Generally, yes, though if your listener makes a getChild() call on a child
that wasn't previously instantiated, it would cause that child to be
created.
Why does a HREF trigger the instantiation of a model and not a static
text child for instance ?
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