[Interest] Qt3D memory leaks
Igor Mironchik
igor.mironchik at gmail.com
Thu Apr 13 20:43:51 CEST 2017
13.04.2017 20:36, Sean Harmer пишет:
>
>
> On 13/04/2017 16:31, Igor Mironchik wrote:
>> Hi,
>>
>>
>> 13.04.2017 17:55, Igor Mironchik пишет:
>>>
>>> Am I right that QEntity doesn't delete its children on destruction and
>>> just removes them from scene?
>>
>> I asked this in context of QEntity::addComponent()...
>>
>> Seems that entity doesn't delete anything. And documentation is unclear
>> in it:
>>
>> voidQEntity::addComponent(QComponent <qt3dcore-qcomponent.html>*comp)
>>
>> Adds a new reference to the component comp.
>>
>> Note: If the Qt3DCore::QComponent <qt3dcore-qcomponent.html> has no
>> parent, the Qt3DCore::QEntity <qt3dcore-qentity.html> will set itself as
>> its parent thereby taking ownership of the component.
>>
>>
>> As I can guess it doesn't take ownership. Because of it I have few leaks
>> at exit but not in restart of tree...
>
> The entity takes ownership of any components that are parentless when
> added. This is done using the usual QObject ownership mechanism so the
> components will be deleted by the entity when it is being destroyed
> just like any other QObject parent. There may be a leaks elsewhere but
> I don't think this is it. There were some leaks related to VAOs fixed
> around the time of the 5.8.0 release. I can't recall if they made it
> into 5.8.0 or not off the top of my head. Please try with a build from
> the 5.9 branch in git.
Yes, you are right. QEntity really deletes all children. I checked it.
Then I have no idea what it can be. Every restart of the 5 years tree
loses ~30 - 40 MB of memory.
>
> Cheers,
>
> Sean
>
>>
>>>
>>>>
>>>> Are those numbers for Linux or Windows?
>>>>
>>>>>
>>>>>
>>>>> 13.04.2017 15:39, william.crocker at analog.com пишет:
>>>>>> On 04/13/2017 08:34 AM, Igor Mironchik wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> Strange, I launch 3Dtree on Linux under valgrind:
>>>>>>>
>>>>>>> ==4321== HEAP SUMMARY:
>>>>>>> ==4321== in use at exit: 439,965 bytes in 6,185 blocks
>>>>>>> ==4321== total heap usage: 2,207,719 allocs, 2,201,534 frees,
>>>>>>> 1,241,469,509
>>>>>>> bytes allocated
>>>>>>> ==4321==
>>>>>>> ==4321== LEAK SUMMARY:
>>>>>>> ==4321== definitely lost: 1,080 bytes in 10 blocks
>>>>>>> ==4321== indirectly lost: 7,609 bytes in 55 blocks
>>>>>>> ==4321== possibly lost: 416 bytes in 1 blocks
>>>>>>> ==4321== still reachable: 430,860 bytes in 6,119 blocks
>>>>>>> ==4321== suppressed: 0 bytes in 0 blocks
>>>>>>>
>>>>>>
>>>>>> Check the virtual image size on Linux,
>>>>>> just to make sure it is not growing as well.
>>>>>> That is the bottom line.
>>>>>>
>>>>>>> But on my Windows OS after each restart of tree I receive plus
>>>>>>> ~100MB additional
>>>>>>> memory.
>>>>>>>
>>>>>>> As I can see this memory still reachable. But why 3Dtree allocates
>>>>>>> more and more
>>>>>>> memory and doesn't use freed one?
>>>>>>>
>>>>>>> 13.04.2017 9:58, Sean Harmer пишет:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> On 13/04/2017 07:09, Igor Mironchik wrote:
>>>>>>>>> Hello,
>>>>>>>>>
>>>>>>>>> 3Dtree has been updated. Now autumn is animated. Removed
>>>>>>>>> hand-made
>>>>>>>>> classes of leaf geometry and mesh. Now example uses ready mesh
>>>>>>>>> prepared
>>>>>>>>> in Blender. Modified a little constants of the tree. Example
>>>>>>>>> looks nice.
>>>>>>>>> This is a benchmark of your video card, because leafs and
>>>>>>>>> branches are
>>>>>>>>> stand alone objects (QEntity). For example 5 years tree has ~ 900
>>>>>>>>> objects. My Intel Pentium with Intel HD graphics normally paint
>>>>>>>>> only 5
>>>>>>>>> years tree, 6 years tree starts to slow down.
>>>>>>>>
>>>>>>>> Yes, at present each entity with a material/geometry renderer
>>>>>>>> combo gets
>>>>>>>> translated to an OpenGL draw call. We are looking to add batching
>>>>>>>> (similar to
>>>>>>>> how Qt Quick 2 works) but it's not there yet.
>>>>>>>>
>>>>>>>> If you don't need to address each individual leaf/branch in your
>>>>>>>> object model.
>>>>>>>> E.g. if you're just rendering them, then you can get *much*
>>>>>>>> better performance
>>>>>>>> by using instanced rendering.
>>>>>>>>
>>>>>>>> Essentially you have one entity representing all leaves. This
>>>>>>>> entity contains
>>>>>>>> the material and geometry renderer as normal. The positions and
>>>>>>>> any other
>>>>>>>> custom properties that vary between instances (rotation, leaf
>>>>>>>> size, leaf
>>>>>>>> colour etc) should be placed into an additional attribute/buffer
>>>>>>>> and provided
>>>>>>>> to the geometry renderer. On this attribute, set the divisor
>>>>>>>> property to 1
>>>>>>>> meaning that 1 piece of data maps to 1 instance of the leave in
>>>>>>>> the scene.
>>>>>>>> With this approach you will be able to render 10,000's leaves in
>>>>>>>> a single draw
>>>>>>>> call. It maps through to a call to glDrawElementsInstanced() in
>>>>>>>> case you want
>>>>>>>> to read up on it. Essentially you're moving the for loop over
>>>>>>>> each leaf on to
>>>>>>>> the GPU.
>>>>>>>>
>>>>>>>> Typically, you'd have your data for the leaves in an array in C++
>>>>>>>> and use this
>>>>>>>> to populate the leaf instance buffer.
>>>>>>>>
>>>>>>>> The plan is to have a batcher that uses this instancing facility.
>>>>>>>>
>>>>>>>> Cheers,
>>>>>>>>
>>>>>>>> Sean
>>>>>>>>
>>>>>>>>>
>>>>>>>>> And one more - now you can rotate the tree with the left mouse
>>>>>>>>> button.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> 11.04.2017 12:15, Igor Mironchik пишет:
>>>>>>>>>>
>>>>>>>>>> Hi,
>>>>>>>>>>
>>>>>>>>>> I fixed a little 3Dtree. Now branches positions are correct.
>>>>>>>>>> And I
>>>>>>>>>> know that not all leafs is visible (this is because leaf
>>>>>>>>>> geometry is
>>>>>>>>>> implemented as plain which renders only on one side).
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> 10.04.2017 13:20, Igor Mironchik пишет:
>>>>>>>>>>>
>>>>>>>>>>> Hello,
>>>>>>>>>>>
>>>>>>>>>>> I guess that Qt3D has huge memory leaks.
>>>>>>>>>>>
>>>>>>>>>>> You can check it on this example:
>>>>>>>>>>> https://github.com/igormironchik/3Dtree
>>>>>>>>>>>
>>>>>>>>>>> It's 3D tree, that grows year by year.
>>>>>>>>>>>
>>>>>>>>>>> By default tree will grow 5 years (5 minutes).
>>>>>>>>>>>
>>>>>>>>>>> When tree grown you can restart tree. And here I delete all
>>>>>>>>>>> resources:
>>>>>>>>>>>
>>>>>>>>>>> void
>>>>>>>>>>>
>>>>>>>>>>> MainWindowPrivate::createTree()
>>>>>>>>>>> {
>>>>>>>>>>> if(m_tree)
>>>>>>>>>>> {
>>>>>>>>>>> for(constauto&e:m_rootEntity->childNodes())
>>>>>>>>>>> e->deleteLater();
>>>>>>>>>>> }
>>>>>>>>>>> m_tree=newBranch(m_startPos,m_endPos,c_startBranchRadius,
>>>>>>>>>>> true,m_rootEntity);
>>>>>>>>>>> m_tree->setAge(0.0f);
>>>>>>>>>>> m_tree->updatePosition();
>>>>>>>>>>> m_tree->placeLeafs();
>>>>>>>>>>> }
>>>>>>>>>>>
>>>>>>>>>>> But a lot of memory are eaten.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
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