I am actually use Qt 5.8 branch from Git, I have some performances and stability regression compared to the 5.7 release.
I can't run my application in Debug mode (tested with mingw and VS 2013) with both Qt versions (5.7 and 5.8=), it runs in release but behavior change fast when I do very small changes in my code. It seems that the version 5.7 is able to support more complexe scenes than Qt 5.8 and performances are twice better. As much as I can tell for the moment stability/performances issues cames from threading management. When trying to load a scene in debug mode with Qt 5.8 it often break in T QGenericAtomicOps::load(const T &_q_value) from a pooled thread. Here is the full call stack : > Qt53DRenderd.dll!QGenericAtomicOps<QAtomicOpsBySize<4> >::load<int>(const int & _q_value) Line 90 C++ Qt53DRenderd.dll!QBasicAtomicInteger<int>::load() Line 99 C++ Qt53DRenderd.dll!QtPrivate::RefCount::isShared() Line 101 C++ Qt53DRenderd.dll!QVector<Qt3DRender::Render::ClearBufferInfo>::isDetached() Line 108 C++ Qt53DRenderd.dll!QVector<Qt3DRender::Render::ClearBufferInfo>::detach() Line 384 C++ Qt53DRenderd.dll!QVector<Qt3DRender::Render::ClearBufferInfo>::begin() Line 204 C++ Qt53DRenderd.dll!Qt3DRender::Render::FrameGraphVisitor::visit::__l78::<lambda>() Line 326 C++ Qt53DRenderd.dll!Qt3DRender::Render::GenericLambdaJob<void <lambda>(void) >::run() Line 78 C++ Qt53DCored.dll!Qt3DCore::AspectTaskRunnable::run() Line 91 C++ Qt5Cored.dll!QThreadPoolThread::run() Line 99 C++ Qt5Cored.dll!QThreadPrivate::start(void * arg) Line 380 C++ [External Code] [Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll] It breaks because the QBasicAtomicInteger pointer is allready free (0xFEEEFEEE). And for performance issues it seems to come from synchronization between thread, so I am trying to reduce the number of Qt3D objects (QShaderProgram, Texture,...) by sharing them, but doing this can lead in rendering issues or crashs. I want to help to improve stability (first) and performances, but I don't have a great experience in thread debugging and on how the Qt3D backend works. So I would be happy to get some hints to improve my feedbacks or doing more to help. -- Xavier
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