Q. What is Shared Memory Programming?

We know all processors share a common memory in shared memory model. Every processor can be assigned a separate portion of program stored in memory to execute with data stored in specified locations. Every processor does calculation independently with data assigned to them by controlling program known as the main program. After finishing their calculations all of these processors unite the main program. The main program completes only after all child processes have been finished completely. There are plentiful alternatives to apply these ideas by high level programming. Few of them are:

i)  Employing heavy weight processes.

ii) Employing threads. (E.g. Pthreads).

iii) Using a totally new programming language for parallel programming (E.g. Ada).

iv) Employing library routines with existing sequential programming language.

v) Editing the syntax of an existing sequential programming language to create a parallel programming language (e.g. UPC).

vi) Using an existing sequential programming language supplemented with compiler directives for specifying parallelism (e.g.  OpenMP)

We will take the last alternative. We will also give an introduction to shared programming employing library routines with an existing sequential programming language.