[kepler-dev] change proposal for ptolemy.vergil.tree.EntityTreeModel class.

[Christopher Brooks]

Hi Jianwu,
Thanks, I folded this into the devel trunk and the 8.0 branch.

_Christopher

On 9/24/10 9:54 AM, Jianwu Wang wrote:
> Hi Christopher,
>
> Since WeakReference.get() could return null, we'd better check it after using this function. So I changed this class a little big more. Please find new class from the attachment and check it in if you
> think it is proper. Thanks.
>
> On 9/20/10 6:14 PM, Christopher Brooks wrote:
>> Hi Jianwu,
>>
>> Your change looks ok to me. The diff between what you sent and what
>> is in the tree is below:
>>
>> bash-3.2$ diff ~/Downloads/EntityTreeModelNew.java EntityTreeModel.java
>> 30d29
>> < import java.lang.ref.WeakReference;
>> 64c63
>> < public class EntityTreeModelNew implements TreeModel {
>> ---
>> > public class EntityTreeModel implements TreeModel {
>> 70c69
>> < public EntityTreeModelNew(NamedObj root) {
>> ---
>> > public EntityTreeModel(NamedObj root) {
>> 82c81
>> < _listenerList.add(new WeakReference(listener));
>> ---
>> > _listenerList.add(listener);
>> 176c175
>> < _listenerList.remove(new WeakReference(listener));
>> ---
>> > _listenerList.remove(listener);
>> 188c187
>> < TreeModelListener listener = (TreeModelListener) ((WeakReference)listeners.next()).get();
>> ---
>> > TreeModelListener listener = (TreeModelListener) listeners.next();
>> 263c262
>> < private List _listenerList = new LinkedList<WeakReference>();
>> ---
>> > private List _listenerList = new LinkedList();
>>
>>
>> I folded in the change and added a comment:
>>
>> /** Add a listener to this model.
>> * @param listener The listener to add.
>> * @see #removeTreeModelListener(TreeModelListener)
>> */
>> public void addTreeModelListener(TreeModelListener listener) {
>> // In http://bugzilla.ecoinformatics.org/show_bug.cgi?id=4801,
>> // Jianwu Wang found that the _listenerList attribute in
>> // ptolemy.vergil.tree.EntityTreeModel was leaking memory.
>> // This attribute keeps holding some references, so that
>> // instances of EntityTreeModel and its sub-classes can not be
>> // GCed when a window is open and closed.
>> //
>> // When it and its sub-classes are used in Kepler,
>> // addTreeModelListener() and removeTreeModelListener()
>> // functions of EntityTreeModel class are called implicitly.
>> // Jianwu did not find a good way to clean up after a window
>> // is closed. Changing the _listenerList attribute using
>> // WeakReference fixe the leak.
>> _listenerList.add(new WeakReference(listener));
>> }
>>
>> I updated the 8.0 release branch, thanks for the patch!
>>
>> Derik, I think you would want this in the 2.1 release. I'm still working on deterimining
>> if ptolemy-8.0.0 is what should be shipped with Kepler 2.1.
>>
>> _Christopher
>>
>>
>> On 9/20/10 4:27 PM, Jianwu Wang wrote:
>>> As I mentioned at http://bugzilla.ecoinformatics.org/show_bug.cgi?id=4801, I found one class might need to be changed for memory leak. It's the _listenerList attribute in
>>> ptolemy.vergil.tree.EntityTreeModel. One memory leak I'm tracing down is that this attribute keeps holding some references, so that instances of EntityTreeModel and its sub-classes can not be GCed
>>> when a window is open and closed.
>>>
>>> When it and its sub-classes are used in Kepler, addTreeModelListener() and removeTreeModelListener() functions of EntityTreeModel class are called implicitly. I haven't find good ways to clean
>>> up after a window is closed.
>>>
>>> If changing the _listenerList attribute using WeakReference, it will be able to fix the leak.
>>
>
>

-- 
Christopher Brooks, PMP                       University of California
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