Programs Process heap space is not infinite. Rather, it is typically bounded by the sum of the amount of physical memory and the swap space allocated to the operating system by the administrator. For example, a system with 1GB of physical memory configured with 2GB of swap space may be able to allocate at most 3GB of heap space total to all running processes (minus the size of the operating system itself and the text and data segments of all running processes). Once all virtual memory has been allocated, requests for more memory will fail. As discussed in MEM32-C. Detect and handle memory allocation errors, programs that fail to check for and properly handle memory allocation failures will have undefined behavior and are likely to crash when heap space is exhausted. Heap exhaustion can result from:
...
If malloc() is unable to return the requested memory, it returns NULL instead.
However, simply checking for and handling memory allocation failures may not be sufficient. Programs such as long running servers that manipulate large data sets need to be designed in a way that permits them to deliver their services when system resources, including the heap, are in short supply. Making use of additional storage devices, such as disk space or databases, is essential in such systems.
Noncompliant Code Example
...