What's the graceful way of handling out of memory situations in C/C++?

Question

I'm writing an caching app that consumes large amounts of memory.

Hopefully, I'll manage my memory well enough, but I'm just thinking about what to do if I do run out of memory.

If a call to allocate even a simple object fails, is it likely that even a syslog call will also fail?

EDIT: Ok perhaps I should clarify the question. If malloc or new returns a NULL or 0L value then it essentially means the call failed and it can't give you the memory for some reason. So, what would be the sensible thing to do in that case?

EDIT2: I've just realised that a call to "new" can throw an exception. This could be caught at a higher level so I can perhaps gracefully exit further up. At that point, it may even be possible to recover depending on how much memory is freed. In the least I should by that point hopefully be able to log something. So while I have seen code that checks the value of a pointer after new, it is unnecessary. While in C, you should check the return value for malloc.

Answer 1

Doesn't this question make assumptions regarding overcommitted memory?

I.e., an out of memory situation might not be recoverable! Even if you have no memory left, calls to malloc and other allocators may still succeed until the program attempts to use the memory. Then, BAM!, some process gets killed by the kernel in order to satisfy memory load.