COOPERATING PROCESSES

Advantages of process cooperation

• Information sharing
• Computation speed-up
• Modularity
• Convenience

Independent process cannot affect/be affected by the execution of another process, cooperating ones can

Issues

• Communication
• Avoid processes getting into each other’s way
• Ensure proper sequencing when there are dependencies

Common paradigm: producer-consumer

• unbounded-buffer - no practical limit on the size of the buffer
• bounded-buffer - assumes fixed buffer size

INTERPROCESSES COMMUNICATION

For communication and synchronization

• Shared memory
• OS provided IPC

Message system

• no need for shared variable
• two operations
• send(message) – message size fixed or variable
• receive(message)

If P and Q wish to communicate, they need to

• establish a communication link between them
• exchange messages via send/receive

Implementation of communication link

• physical (e.g., shared memory, hardware bus)
• logical (e.g., logical properties)
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