在虚幻引擎中删除NXOpen对象时崩溃

Question

你好，堆栈溢出社区，

第一次问。

我正在开发一个原型，用于在VR中使用虚幻引擎对CAD数据进行建模。我已经设法让我的虚幻项目在我的计算机辅助设计系统Siemens NX上构建，或者更确切地说，是NXOpen应用编程接口。

总体而言，该应用程序接口工作正常，我可以调用NXOpen函数并创建基本对象，但一些操作会导致崩溃，我猜测这与内存管理有关。我不能完全理解到底发生了什么。

例如，我有创建NX块功能的代码，可以很好地工作。之后，我将需要一个实体对象，它存储在块功能中。访问也是有效的，但是当‘but’超出范围时，它就会崩溃。当访问NX功能中的所有类型的数据时，也会发生类似的崩溃。这个虚拟代码经常触发崩溃：

    // 'block' gets created here

    if (block) {
        std::vector<NXOpen::Body*> bodies = block->GetBodies();
        if (bodies.size() > 0) {
            NXOpen::Body* body = bodies.front();
        }
    } // <-- this line crashes

Exception thrown: read access violation.
**flag** was 0xFFFFFFFFFFFFFFFF. occurred

    [Inline Frame] UE4Editor-Core.dll!__TBB_machine_cmpswp1(volatile void *) Line 69    C++
>   [Inline Frame] UE4Editor-Core.dll!__TBB_TryLockByte(unsigned char &) Line 917   C++
    UE4Editor-Core.dll!__TBB_LockByte(unsigned char & flag) Line 924    C++
    [Inline Frame] UE4Editor-Core.dll!MallocMutex::scoped_lock::{ctor}(MallocMutex &) Line 66   C++
    UE4Editor-Core.dll!rml::internal::Block::freePublicObject(rml::internal::FreeObject * objectToFree) Line 1382   C++
    [Inline Frame] UE4Editor-Core.dll!rml::internal::internalPoolFree(rml::internal::MemoryPool * memPool, void *) Line 2571    C++
    UE4Editor-Core.dll!rml::internal::internalFree(void * object) Line 2595 C++
    UE4Editor-Core.dll!FMemory::Free(void * Original) Line 76   C++
    UE4Editor-GestEnUE-Win64-DebugGame.dll!operator delete(void * Ptr, unsigned __int64 Size) Line 6    C++
    [External Code] 
    UE4Editor-GestEnUE-Win64-DebugGame.dll!UNXConnection::AddPointSetsToBody(const FString & name) Line 268 C++
    UE4Editor-GestEnUE-Win64-DebugGame.dll!ANXPart::AddCylinder(FVector pos, FVector axis, float height, float diameter, bool WorldSpace) Line 103  C++
    UE4Editor-GestEnUE-Win64-DebugGame.dll!ANXPart::execAddCylinder(UObject * Context, FFrame & Stack, void * const Z_Param__Result) Line 18    C++
    UE4Editor-CoreUObject.dll!UFunction::Invoke(UObject * Obj, FFrame & Stack, void * const Z_Param__Result) Line 4643  C++
    UE4Editor-CoreUObject.dll!UObject::CallFunction(FFrame & Stack, void * const Z_Param__Result, UFunction * Function) Line 904    C++
    [Inline Frame] UE4Editor-CoreUObject.dll!FFrame::Step(UObject *) Line 319   C++
    UE4Editor-CoreUObject.dll!UObject::ProcessContextOpcode(FFrame & Stack, void * const Z_Param__Result, bool bCanFailSilently) Line 2314  C++
    [Inline Frame] UE4Editor-CoreUObject.dll!FFrame::Step(UObject *) Line 319   C++
    UE4Editor-CoreUObject.dll!UObject::execLetObj(UObject * Context, FFrame & Stack, void * const Z_Param__Result) Line 2136    C++
    [Inline Frame] UE4Editor-CoreUObject.dll!FFrame::Step(UObject *) Line 319   C++
    UE4Editor-CoreUObject.dll!ProcessLocalScriptFunction(UObject * Context, FFrame & Stack, void * const Z_Param__Result) Line 974  C++
    UE4Editor-CoreUObject.dll!ProcessScriptFunction<void (__cdecl*)(UObject *,FFrame &,void *)>(UObject * Context, UFunction * Function, FFrame & Stack, void * const Z_Param__Result, void(*)(UObject *, FFrame &, void *) ExecFtor) Line 809  C++
    UE4Editor-CoreUObject.dll!ProcessLocalFunction(UObject * Context, UFunction * Fn, FFrame & Stack, void * const Z_Param__Result) Line 1033   C++
    [Inline Frame] UE4Editor-CoreUObject.dll!FFrame::Step(UObject *) Line 319   C++
    UE4Editor-CoreUObject.dll!ProcessLocalScriptFunction(UObject * Context, FFrame & Stack, void * const Z_Param__Result) Line 974  C++
    UE4Editor-CoreUObject.dll!ProcessScriptFunction<void (__cdecl*)(UObject *,FFrame &,void *)>(UObject * Context, UFunction * Function, FFrame & Stack, void * const Z_Param__Result, void(*)(UObject *, FFrame &, void *) ExecFtor) Line 809  C++
    UE4Editor-CoreUObject.dll!ProcessLocalFunction(UObject * Context, UFunction * Fn, FFrame & Stack, void * const Z_Param__Result) Line 1033   C++
    [Inline Frame] UE4Editor-CoreUObject.dll!FFrame::Step(UObject *) Line 319   C++
    UE4Editor-CoreUObject.dll!UObject::ProcessContextOpcode(FFrame & Stack, void * const Z_Param__Result, bool bCanFailSilently) Line 2314  C++
    [Inline Frame] UE4Editor-CoreUObject.dll!FFrame::Step(UObject *) Line 319   C++
    UE4Editor-CoreUObject.dll!ProcessLocalScriptFunction(UObject * Context, FFrame & Stack, void * const Z_Param__Result) Line 974  C++
    UE4Editor-CoreUObject.dll!ProcessScriptFunction<void (__cdecl*)(UObject *,FFrame &,void *)>(UObject * Context, UFunction * Function, FFrame & Stack, void * const Z_Param__Result, void(*)(UObject *, FFrame &, void *) ExecFtor) Line 809  C++
    UE4Editor-CoreUObject.dll!ProcessLocalFunction(UObject * Context, UFunction * Fn, FFrame & Stack, void * const Z_Param__Result) Line 1033   C++
    [Inline Frame] UE4Editor-CoreUObject.dll!FFrame::Step(UObject *) Line 319   C++
    UE4Editor-CoreUObject.dll!ProcessLocalScriptFunction(UObject * Context, FFrame & Stack, void * const Z_Param__Result) Line 974  C++
    UE4Editor-CoreUObject.dll!UObject::ProcessInternal(UObject * Context, FFrame & Stack, void * const Z_Param__Result) Line 1058   C++
    UE4Editor-CoreUObject.dll!UFunction::Invoke(UObject * Obj, FFrame & Stack, void * const Z_Param__Result) Line 4643  C++
    UE4Editor-CoreUObject.dll!UObject::ProcessEvent(UFunction * Function, void * Parms) Line 1464   C++
    UE4Editor-Engine.dll!AActor::ProcessEvent(UFunction * Function, void * Parameters) Line 769 C++
    UE4Editor-GestEnUE-Win64-DebugGame.dll!ABuilderBase::commit() Line 37   C++
    UE4Editor-GestEnUE-Win64-DebugGame.dll!AGestEnLeapPawn::Tick(float DeltaTime) Line 138  C++
    UE4Editor-Engine.dll!AActor::TickActor(float DeltaSeconds, ELevelTick TickType, FActorTickFunction & ThisTickFunction) Line 970 C++
    UE4Editor-Engine.dll!FActorTickFunction::ExecuteTick(float DeltaTime, ELevelTick TickType, ENamedThreads::Type CurrentThread, const TRefCountPtr<FGraphEvent> & MyCompletionGraphEvent) Line 164    C++
    [Inline Frame] UE4Editor-Engine.dll!FTickFunctionTask::DoTask(ENamedThreads::Type) Line 285 C++
    UE4Editor-Engine.dll!TGraphTask<FTickFunctionTask>::ExecuteTask(TArray<FBaseGraphTask *,FDefaultAllocator> & NewTasks, ENamedThreads::Type CurrentThread) Line 842  C++
    [Inline Frame] UE4Editor-Core.dll!FBaseGraphTask::Execute(TArray<FBaseGraphTask *,FDefaultAllocator> & CurrentThread, ENamedThreads::Type) Line 511 C++
    UE4Editor-Core.dll!FNamedTaskThread::ProcessTasksNamedThread(int QueueIndex, bool bAllowStall) Line 686 C++
    UE4Editor-Core.dll!FNamedTaskThread::ProcessTasksUntilQuit(int QueueIndex) Line 582 C++
    [Inline Frame] UE4Editor-Core.dll!FTaskGraphImplementation::ProcessThreadUntilRequestReturn(ENamedThreads::Type) Line 1406  C++
    UE4Editor-Core.dll!FTaskGraphImplementation::WaitUntilTasksComplete(const TArray<TRefCountPtr<FGraphEvent>,TInlineAllocator<4,FDefaultAllocator> > & Tasks, ENamedThreads::Type CurrentThreadIfKnown) Line 1457 C++
    UE4Editor-Engine.dll!FTickTaskSequencer::ReleaseTickGroup(ETickingGroup WorldTickGroup, bool bBlockTillComplete) Line 557   C++
    UE4Editor-Engine.dll!FTickTaskManager::RunTickGroup(ETickingGroup Group, bool bBlockTillComplete) Line 1505 C++
    UE4Editor-Engine.dll!UWorld::RunTickGroup(ETickingGroup Group, bool bBlockTillComplete) Line 789    C++
    UE4Editor-Engine.dll!UWorld::Tick(ELevelTick TickType, float DeltaSeconds) Line 1568    C++
    UE4Editor-UnrealEd.dll!UEditorEngine::Tick(float DeltaSeconds, bool bIdleMode) Line 1618    C++
    UE4Editor-UnrealEd.dll!UUnrealEdEngine::Tick(float DeltaSeconds, bool bIdleMode) Line 403   C++
    UE4Editor-Win64-DebugGame.exe!FEngineLoop::Tick() Line 3967 C++
    [Inline Frame] UE4Editor-Win64-DebugGame.exe!EngineTick() Line 62   C++
    UE4Editor-Win64-DebugGame.exe!GuardedMain(const wchar_t * CmdLine, HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, int nCmdShow) Line 168   C++
    UE4Editor-Win64-DebugGame.exe!WinMain(HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, char * __formal, int nCmdShow) Line 261   C++

如果我正确地理解了callstack，那么当对象被删除时就会发生错误。但为什么这会成为问题所在？会不会是虚幻和NX第三方库都试图管理内存？

有没有人知道导致这些崩溃的原因，甚至知道如何解决它？如果有必要，我很乐意提供更多的信息。

问候，LaRanaRica

Answer 1

我发现在使用NXOpen时，经常使用调试运行时库会导致内存错误。您可以使用链接器设置/MD (代替/MDd)来更改此设置。

Answer 2

我知道这为时已晚，但我有一个比在发布模式下构建而不是在调试模式下构建要好得多的解决方案，因为我以前遇到过这个问题很多次，并使用相同的简单解决方案解决了它。

您可以通过将以下行添加到C++源文件的顶部来修复它，在所有#include之前：

#define _ITERATOR_DEBUG_LEVEL 0