Datagrid column in module causing memory leak

Question

Hi All
I'm having trouble with a DataGrid column preventing a module from being release properly. I can't imagine this is the intended behaviour.
Using this simple test case, a WindowedApplication and an mx:Module I wonder if anyone else can reproduce this problem. The issue goes away if you simply comment out the GridColumn Instance.
Can anyone offer any advice?
Many thanks
James
DataGridTest.mxml
<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009"
                       xmlns:s="library://ns.adobe.com/flex/spark"
                       xmlns:mx="library://ns.adobe.com/flex/mx">
    <fx:Script>
        <![CDATA[
            import mx.core.IVisualElement;
            import mx.events.ModuleEvent;
            import mx.modules.IModuleInfo;
            import mx.modules.ModuleManager;
            private var assetModule:IModuleInfo;
            protected function load_clickHandler(event:MouseEvent):void
                assetModule = ModuleManager.getModule('DataGridTestModule.swf');
                assetModule.addEventListener("ready", getModuleInstance);
                assetModule.load();
            public function getModuleInstance(event:ModuleEvent):void
                var sm:DisplayObject = assetModule.factory.create() as DisplayObject;
                sm.addEventListener("close", closeModule);
                contentHolder.addElement(sm as IVisualElement);
            private function closeModule(event:Event):void
                event.target.removeEventListener("close", closeModule);
                contentHolder.removeElement(event.target as IVisualElement);
                assetModule.unload();
                assetModule = null;
        ]]>
    </fx:Script>
    <s:VGroup width="100%" height="100%">
        <s:HGroup >
            <s:Button id="load" label="Load" click="load_clickHandler(event)"/>
        </s:HGroup>
        <s:BorderContainer id="contentHolder" width="100%" height="100%"/>
    </s:VGroup>
</s:WindowedApplication>
DataGridTestModule.mxml
<?xml version="1.0" encoding="utf-8"?>
<mx:Module xmlns:fx="http://ns.adobe.com/mxml/2009"
                      xmlns:s="library://ns.adobe.com/flex/spark"
                      xmlns:mx="library://ns.adobe.com/flex/mx"
                      layout="absolute" xmlns:components="components.*">
    <fx:Script>
        <![CDATA[
            protected function close_clickHandler(event:MouseEvent):void
                dispatchEvent(new Event('close', true, false))
        ]]>
    </fx:Script>
    <s:BorderContainer id="contacts"
                       width="100%" height="100%"
                       backgroundAlpha="0"
                       borderVisible="false">
        <s:layout>
            <s:VerticalLayout/>
        </s:layout>
        <s:Button id="close" label="Close" click="close_clickHandler(event)"/>
        <s:DataGrid id="queries" >
            <s:columns>
                <s:ArrayList>
                    <s:GridColumn/> <!-- Comment out this GridColumn instance to see the leak disappear -->
                </s:ArrayList>
            </s:columns>
        </s:DataGrid>
    </s:BorderContainer>
</mx:Module>

Answer 1

OK, So I've done some more testing. Creating the GridColumn in AS during the creationComplete event is a slight improvement. It seems to allow the DataGrid and the Module be GC'd, but it's still leaking memory somewhere. I just can't get my head around the Profiler. Also, it's going to be a massive headache if we have to rewrite our application to create all the GridColumns in AS. Surely this shouldn't be necessary?
New test case below:
DataGridTest.mxml
<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009"
                       xmlns:s="library://ns.adobe.com/flex/spark"
                       xmlns:mx="library://ns.adobe.com/flex/mx">
    <fx:Script>
        <![CDATA[
            import mx.collections.ArrayList;
            import mx.core.IVisualElement;
            import mx.events.ModuleEvent;
            import mx.modules.IModuleInfo;
            import mx.modules.ModuleManager;
            import spark.components.gridClasses.GridColumn;
            private var assetModule:IModuleInfo;
            private var sm:DisplayObject;
            protected function load_clickHandler(event:MouseEvent):void
                assetModule = ModuleManager.getModule('DataGridTestModule.swf');
                assetModule.addEventListener("ready", getModuleInstance);
                assetModule.load();
            public function getModuleInstance(event:ModuleEvent):void
                sm = assetModule.factory.create() as DisplayObject;
                sm.addEventListener("close", closeModule);
                contentHolder.addElement(sm as IVisualElement);
            private function closeModule(event:Event):void
                event.target.removeEventListener("close", closeModule);
                contentHolder.removeElement(event.target as IVisualElement);
                assetModule.unload();
                assetModule = null;
        ]]>
    </fx:Script>
    <s:VGroup width="100%" height="100%">
        <s:HGroup >
            <s:Button id="load" label="Load" click="load_clickHandler(event)"/>
        </s:HGroup>
        <s:BorderContainer id="contentHolder" width="100%" height="100%"/>
    </s:VGroup>
</s:WindowedApplication>
DataGridTestModule.mxml
<?xml version="1.0" encoding="utf-8"?>
<mx:Module xmlns:fx="http://ns.adobe.com/mxml/2009"
                      xmlns:s="library://ns.adobe.com/flex/spark"
                      xmlns:mx="library://ns.adobe.com/flex/mx"
                      creationComplete="module1_creationCompleteHandler(event)"
                      layout="absolute" xmlns:components="components.*">
    <fx:Script>
        <![CDATA[
            import flash.utils.setTimeout;
            import mx.collections.ArrayList;
            import mx.events.FlexEvent;
            import spark.components.gridClasses.GridColumn;
             [Bindable]
            private var _col:ArrayList = new ArrayList();
            protected function close_clickHandler(event:MouseEvent):void
                dispatchEvent(new Event('close', true, false))
            protected function module1_creationCompleteHandler(event:FlexEvent):void
                var gc:GridColumn = new GridColumn();
                gc.headerText = 'Test Column';
                _col.addItem(gc);
        ]]>
    </fx:Script>
    <s:BorderContainer width="100%" height="100%">
        <s:layout>
            <s:VerticalLayout/>
        </s:layout>
        <s:Button id="close" label="Close" click="close_clickHandler(event)"/>
        <s:DataGrid id="queries" columns="{_col}"/>
    </s:BorderContainer>
</mx:Module>