It looks like mesh is collected, not root. How does root keep mesh alive?
On Wed, Mar 23, 2016, 9:20 PM Scott Duensing <[email protected]>
wrote:
> I've been working on a game engine and using V8 as the embedded language.
> Everything has been going fairly well, using SWIG to wrap native C++
> classes for use in JS.
>
> Until today.
>
> My test code creates a triangle in JavaScript and sends it to the engine
> to be rendered. It works. For about 5 seconds. Then the 'root' object of
> my scene gets garbage collected by V8 and I'm not sure why. I set a
> breakpoint when the object is destroyed and captured a stack trace:
>
> 0 ComponentMesh::~ComponentMesh componentMesh.cpp 18 0x4cd39e
> 1 ComponentMesh::~ComponentMesh componentMesh.cpp 19 0x4cd472
> 2 _wrap_delete_ComponentMesh componentMesh_wrap.cpp 1788
> 0x435c46
> 3 v8::internal::GlobalHandles::Node::PostGarbageCollectionProcessing(v8
> ::internal::Isolate *) 0x6a7fee
> 4 v8::internal::GlobalHandles::PostScavengeProcessing(int)
> 0x6a7e75
> 5 v8::internal::GlobalHandles::PostGarbageCollectionProcessing(v8::
> internal::GarbageCollector, v8::GCCallbackFlags) 0x6a86ba
> 6 v8::internal::Heap::PerformGarbageCollection(v8::internal::
> GarbageCollector, v8::GCCallbackFlags) 0x6afa77
> 7 v8::internal::Heap::CollectGarbage(v8::internal::GarbageCollector,
> const char *, const char *, v8::GCCallbackFlags) 0x6af054
> 8 v8::internal::Factory::NewRawOneByteString(int, v8::internal::
> PretenureFlag) 0x68677d
> 9 v8::internal::Factory::NewStringFromUtf8(v8::internal::Vector<char
> const>, v8::internal::PretenureFlag) 0x686bb0
> 10 v8::String::NewFromUtf8(v8::Isolate *, const char *, v8::
> NewStringType, int) 0x4d00ea
> 11 ScriptInstance::update scriptInstance.cpp 179 0x41d744
> 12 Scripting::update scripting.cpp 219 0x41609c
> 13 main main.cpp 70 0x4b2331
>
>
>
> As you can see, my scripting system calls update() in the JS code which
> should call render() back in the engine. Except the mesh is being GCed
> before that happens. The JS is:
>
> "use strict";
>
> var root;
>
> function startup(scriptId) {
> var mesh = new ComponentMesh("triangle");
> mesh.addVertex(new Vertex(-1.0, -1.0, 0.0));
> mesh.addVertex(new Vertex( 1.0, -1.0, 0.0));
> mesh.addVertex(new Vertex( 0.0, 1.0, 0.0));
> mesh.addIndex(0);
> mesh.addIndex(1);
> mesh.addIndex(2);
>
> root = new Entity("root");
> root.addComponent(mesh);
> }
>
> function update(delta, event) {
> Engine.render(root);
> }
>
> function shutdown() {
> }
>
>
> Why is 'root' being GCed? The context for this script is Persistent<> and
> I don't call Destroy()/Reset().
>
> The entire codebase is available to browse at
> http://skunkworks.kangaroopunch.com/projects/magrathea/repository
>
> Help? Please? Thanks!
>
>
> Scott
>
>
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