CODEWITHSUNDEEP
memory-leaksgarbage-collectionjvmjavafxjavafx-2
Stas
Stas

Reputation: 152

JavaFX Node objects are not garbage collected

JavaFX (1.2.x and 1.3.x) doesn't seem to allow garbage collection for at least Nodes and Scenes. A Node object is not freed after being removed from Scene (there's no other explicit reference to it).

Here goes example:

var buttonB:Button =
   Button {
       text: "i'm just hanging here"
   }

var buttonC:Button =
   Button {
       text: "hit me to leak memory"
       action: function() {
           buttonB.managed = false;
           delete buttonB from mainBox.content;
           buttonB.skin = null;
           buttonB = null;
           java.lang.System.gc();
       }
   }

def mainBox:HBox =
   HBox {
       hpos: HPos.CENTER
       nodeVPos: VPos.CENTER
       layoutInfo: LayoutInfo {
        width: 800 height: 600
       }
       content: [buttonC, buttonB]
   }

buttonB is never freed. Setting skin to null helps somehow (in VisualVM most of the references to the button disappear) but doesn't fix the issue. I also tried nullifying all members using JavaFX reflection with no luck.

Is it possible to make buttonB eligible for GC and how to do it?

Does the problem persist in JavaFX 2.0?

Upvotes: 2

Views: 2116

Answers (1)

Thirler
Thirler

Reputation: 20760

I found (through visualVM inspection) that JavaFX 1.3 keeps SoftReferences to buffered images (that probably represent rendered versions of Nodes) for nodes that have been removed. For me this was a sort of memory leak, as soft references are cleared depending on the amount of free memory. This isn't a memory leak (OutOfMemoryException will never happen due to this) but for me this was reason to cause very inefficient garbage collecting.

You can use XX:SoftRefLRUPolicyMSPerMB=<N> to reduce the time SoftReferences are kept, this is at a possible (but unlikely) performance penalty though. It sets the number of milliseconds per free MB that an object is kept. Default is 1000 ms.

Upvotes: 6

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