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Showing posts from July, 2011

Memory Leak

Memory Pools are just a section of memory reserved for allocating temporarily to other parts of the application. So, memory leak occurs when you allocate some memory from the heap(or a pool) and then delete all references to that memory without returning it to the pool it was allocated from.

Basically, we are left with less memory to allocate because we have not freed the memory and keep on allocating it.

Structure padding

Structure Padding

Most processors require specific memory alignment on variables certain types. Normally the minimum alignment is the size of the basic type in question, fo instance this is common

char variables can be byte aligned and appear at any byte boundary

short (2 byte) variables must be 2 byte aligned, they can appear at any even byte boundary. This means that 0x10004567 is not a valid location for a short variable but 0x10004566 is.

long (4 byte) variables must be 4 byte aligned, they can only appear at byte boundarys that are a multiple of 4 bytes. This means that 0x10004566 is not a valid location for a long variable but 0x10004568 is.

Structure padding occurs because the members of the structure must appear at the correect byte boundary, to achieve this the compiler puts in padding bytes (or bits if bit fields are in use) so that the structure members appear in the correct location.

e.g.

struct ex{
int i; //assuming int to take 2 bytes
char c;
int j;
};

Here, size of struct will be 6…