Threads and heap

[kaushikagrawal]

Hi folks,

I am working on a crash dump got from a customer and what I see is that 2 of the threads are trying to access the same heap (HeapAlloc) function at the same time. I am not 100% sure if we use Mutexes since I am new to the company but I believe they do. Is it possible for something like HeapAllocation to cause a crash. Please help me out. It might also be heap corruption. I will try to post some code soon, but I would like to get some initial reaction from someone.

Thanks a a lot in advance.

[JVene]

The multi-threaded CRT allocation system (malloc, new, etc) will lock it's own object (critical section I would think) for all calls. It would crash if, for some reason, it's not the multi-threaded version of the library.

Otherwise, it's fairly well nailed down there.

[kaushikagrawal]

Is it possible that one thread which is accessing the heap via win32 API (assuming that it locks that heap as a critical section) but if a thread created by my application is not taking care of that and calling the heap directly via a heapAlloc function would cause a crash - an access violation.

Am I making any sense??

[JVene]

As long as the libraries are the multi-threaded libraries in the setup, this shouldn't be a problem. There can be situations where you link a static library or load a DLL that's built in, say, the non-multi-threaded library, but your application is built with multi-threaded, and you can end up with this problem.

There should be linker complaints, but some linker settings can 'get around' this to generate an invalid executable.

This is rare, though - so after a quick check on the related compiler settings, I'd seriously think in the application code direction.

[kaushikagrawal]

Hi,

I checked all the settings and all of the DLL projects are indeed set to be multi-threaded. Can you give me some pointers as to what can be causing such a problem in the application code. Would really appreciate it.

Thanks.