Producer–Consumer Using Shared Memory and Semaphores

The code in this repository implements the Producer–Consumer problem using shared memory and System V semaphores with strict atomicity requirements.

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Requirements & Constraints

Shared Memory

• Create a shared memory segment using:
  • shmget
  • shmat
• The parent process must remove the shared memory segment using:
  • shmctl

Semaphores

• Use exactly three semaphores:
  1. Mutex semaphore – controls exclusive access to the shared buffer
  2. Empty semaphore – counts empty slots in the buffer
  3. Full semaphore – counts full slots in the buffer
• Semaphore operations must be performed using:
  • semop
• Atomic P() and V() operations must be used
• Do NOT use separate semaphore calls for individual operations

Processes

• The program must create three child processes using fork():
  • Two producers
  • One consumer

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Program Structure

.
├── main.c        # Process creation, synchronization, and cleanup
├── buff.h        # Shared buffer definition
├── buff.c        # Buffer operations
└── README.md     # Assignment documentation

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Compilation & Execution

Compile using GCC:

gcc -Wall -o ass2 main.c buff.c

Run the program:

./ass2

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Synchronization Logic

• Producers:

  • Wait on empty
  • Acquire mutex
  • Insert item into buffer
  • Release mutex
  • Signal full

• Consumer:

  • Wait on full
  • Acquire mutex
  • Remove item from buffer
  • Release mutex
  • Signal empty

All semaphore operations are performed using atomic semop() calls.

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