In any limited-hardware device, memory management is critical. Windows
programmers can be wasteful as it is relatively simple to add more memory into a computer, or
failing that, with modern hard drives, virtual memory is practically unlimited.
In a mobile phone, however, memory resources are not just limited,
but also relatively small. Memory is particularly limited on the stack, and so it is important that software development continuously takes into account the potential for failing to allocate resources. Such issues are dealt with in Symbian OS using two concepts: leaves and the cleanup stack. Leaves provide a lightweight exception-handling mechanism that is lighter on resources than more conventional C++ exception-handling mechanisms. The cleanup stack is a static resource that can be used to clean up dynamically allocated resources on the heap in the event of a leave. If resources are not properly cleaned up in the event of a leave, then memory leaks will occur. These leaks can only be freed up by rebooting the phone (i.e. turning it off and on again). Rebooting a PC is a fairly regular occurrence that usually happens at least once a day.
However, phones may be left on for weeks at a time between reboots and so leaked resources may not be reclaimed for long periods of time, impacting the amount of memory available in the system.
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