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cooperating processes

An Independent process is not affected by other running processes.

Cooperating processes may affect each other, hopefully in some controlled way.

Why cooperating processes?

• information sharing

• computational speedup

• modularity or convenience

It’s hard to find a computer system where processes do not cooperate. Consider the commands you type at the Unix command line. Your shell process and the process that executes your command must cooperate. If you use a pipe to hook up two commands, you have even more process cooperation.

For the processes to cooperate, they must have a way to communicate with each other. Two common methods:

• shared variables – some segment of memory accessible to both processes

• message passing – a process sends an explicit message that is received by another