(C++) I have memory aligned instances allocated on heap, then delete them in another thread. The codes look like this:
ALIGNED class Obj
{
public: ALIGNED_NEW_DELETE
...
};
Thread 1:
Obj *o = new Obj; // overloaded new for aligned memory allocation
postTask(o);
Thread 2:
o->runTask();
delete o; // overloaded delete for aligned memory deletion
// "delete" statement crashes
The delete statement in thread 2 will give an assertion error in Visual Studio 2013 (_BLOCK_TYPE_IS_VALID). Strangely, if i delete the object in the creation thread, everything runs fine.
Why does this happen? What's the solution?
EDIT:
@galop1n: Actually what i am currently using is Eigen's built-in new/delete operators EIGEN_MAKE_ALIGNED_OPERATOR_NEW. I also tried my own operators, both failed.
For Eigen's operators, please look up its source yourself.
For my allocators:
void* operator new(size_t size){ return alignedMalloc(size, align); }
void operator delete(void* ptr) { alignedFree(ptr); }
void* operator new[](size_t size) { return alignedMalloc(size, align); }
void operator delete[](void* ptr) { alignedFree(ptr); }
void* alignedMalloc(size_t size, size_t align)
{
char* base = (char*)malloc(size + align + sizeof(int));
if (base == nullptr)
ASSERT(0, "memory allocation failed");
char* unaligned = base + sizeof(int);
char* aligned = unaligned + align - ((size_t)unaligned & (align - 1));
((int*)aligned)[-1] = (int)((size_t)aligned - (size_t)base);
return aligned;
}
void alignedFree(const void* ptr) {
int ofs = ((int*)ptr)[-1];
free((char*)ptr - ofs);
}
And the ALIGNED macro is __declspec(align(16)). It crashes with or without the "ALIGNED" attribute.
This is awkward, the problem is in Thread 2, The Obj* is casted into a base class' pointer Task*, and for the utter stupidity: ~Task() is not virtual:
class Task
{
public:
~Task(); // <-- not virtual, therefore it crashes
...
}
ALIGNED class Obj : public Task
{ ... }
Should have discovered this problem much much earlier. Because, as in my description of the problem, i said it myself it gives an assertion error: _BLOCK_TYPE_IS_VALID, this is a visual studio debug lib's stuff for the default delete operator, which means it didn't even run into my overloaded delete operator, which ultimately means I missed a "virtual".
It's my bad that i even forgot to add the class inheritance to the question.
Sometimes, i can be stuck at a problem for hours or even days. But after i posted the issue online, i can immediately find the answer. Dunno if any of you have similar problems before; perhaps i've put too much stress onto myself.
Still, thanks you, Internet.
Collected from the Internet
Please contact [email protected] to delete if infringement.
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