跨进程内存管理

Question

I wish to allocate data on a shared memory segment in one process and free it in another.

I allocate it in process 1 (Proc1) using the following line: new_Class* pData = managed_windows_shared_memory_segment.construct<new_Class>(anonymous_instance) ()

I then convert the pointer to a handle get_handle_from_address(pData) , transfer it to the other process (Proc2) convert it back to a pointer static_cast<new_Class*>managed_windows_shared_memory_segment.get_address_from_handle(handle) and try to deallocate it there. (after Proc1 died i might add)

when i try to deallocate it in proc 2 with destroy_ptr(pData) I get annoying an annoying exception: "Unhandled exception at 0x0000000000000000" and trying to use deallocate(pData) doesn't fare better.

when i deallocate from Proc1 all is well, it's just the deallocation from from Proc2 that appears problematic.

Any Ideas?

---

The problem was caused by a virtual destructor in a base class. note to self: Don't use virtual functions on shared memory, the Virtual method table is NOT cross process.

I would like to thank Chad. He rightly pointed out that i should post relevant code which caused me to take a closer look at an obscure base class.

Answer 1

I heartily suggest using smart pointers, as you would with non-interprocess allocations.

Of course, regular shared_ptr doesn't cut it unless the refcount/weakref are also allocated in the shared memory segment.

Luckily, Boost Interprocess comes fully charged with

• boost::interprocess::shared_ptr<T>
• boost::interprocess::make_shared<T>(...)

See http://www.boost.org/doc/libs/1_58_0/doc/html/interprocess/interprocess_smart_ptr.html#interprocess.interprocess_smart_ptr.shared_ptr

There are also scoped_ptr<> , unique_ptr<> and even an intrusive_ptr<> for all your peculiar needs :)