Memory leaks / lifetime best practices

[prideout]

Has anyone tested the sample apps for memory leaks? For example, try running the shapeToUrl function in a loop and looking at Chrome's Task Manager or performance tools.

I'm asking because the Emscripten docs strongly recommend explicit delete calls for all classes:

https://emscripten.org/docs/porting/connecting_cpp_and_javascript/embind.html#memory-management

For example, consider the following code from a starter template:

// Tell OpenCascade that we want our shape to get meshed
new oc.BRepMesh_IncrementalMesh_2(shape, 0.1, false, 0.1, false);

I think this should actually be:

// Tell OpenCascade that we want our shape to get meshed
const incmesh = new oc.BRepMesh_IncrementalMesh_2(shape, 0.1, false, 0.1, false);
incmesh.delete();

[donalffons]

You are correct, the example code is currently leaking memory left and right. For some smaller applications, this might not be a real problem (if the ocjs life time is relatively short and/or the amount of leaked memory is small). But generally, you would have to do memory cleanup, like you suggested.

The examples / starter templates currently don't do memory cleanup, because I think that makes them easier to read / understand (all the .delete() calls can lead to very lengthy code). But it might be a good idea to have a documentation page on that situation...

Both OpenCascade / OCCT and Emscripten support SmartPointers (OCCT handle or shared_ptr). So, there is a chance that the amount of memory cleanup code could be reduced with those concepts in a future version, but that would need more investigation...

Using the FinalizationRegistry API might also help with reducing the amount of memory cleanup code you have to maintain.