1.2 The Memory Concept
Memory management or the act of managing computer memory is defined as a way to
dynamically allocate portions of memory to a program at its request. It is also the act of
freeing memory for reuse when data is no longer needed (a task done by browsers).
A thread of execution is the smallest sequence of programmed instructions that can be
managed independently. Multiple threads can coexist within the same process and share
the same memory area.
In general terms, we can subdivide memory into two distinct areas, the stack and the
heap.
A stack is a restricted data structure. Only a small number of operations can be
performed in it. Usually this data points to bigger data on the heap. Like for example,
variables pointing to objects.
When these operations are done, the data is automatically cleared to give space for the
next batch. In a way the stack acts as scratchpad for memory operations, and for the most
part, only quick data such as pointers (variable names) reside in the stack.
The heap is a completely different mater. To start with, in the heap, data is not as well
organized as in the stack, and chunks of data can be stored ad-hoc because in the heap, if
a piece of data gets larger, memory can be allocated as needed. This makes the heap
slower than the stack. Stack memory is faster because in the stack, each data set has a
specific size under strict management.
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