Question

2. In the context of inter-process communication:
a) Explain the advantage(s) of a shared memory solution.
b) Explain the advantage(s) of a message passing solution.
c) Explain the semantics of a blocking read.

Answer 1

2. a)

Shared Memory :

It is one of the models of inter-process communication (IPC) where two or more than two processes share a common portion of memory area (virtual memory space) to communicate among each other. The advantages of this model are enlisted below.

• Shared memory model is the fastest form of IPC .
• It allows the user to perform multiple tasks at a time .
• Long task can be divided into some small tasks which can be executed in parallel . So the computation power of computer is increased .

b)

Message Passing :

In this IPC model two processes communicate with each other by sending and receiving  messages . The message can be signals, functions, complex data structures, or data packets . There are two types of message passing Synchronous and Asynchronous . The advantages of this model are enlisted below.

• It is easier to build system using this model as the concept of this model very easy to implement.
• This IPC model has tolerance of higher communication latency .
• There is a wide range of message passing libraries (i.e. mpi, pvm,...) are available .

c)

Blocking Read :

There are couple of IPC protocols are available to ensure that the data is delivered to the destination and the delivery information should be returned to the sender process. We can achieve this by blocking the sender process for a certain period of time . A blocking read will wait until there is data available or data gets expired or there is any time out  and then it returns from the function call.