1).What is Asynchronous concurrent processes? 2). Explain the difference between concurrency and synchronization?

 1) 

Synchronization:

means acquiring a reentrant lock on an object. The lock is released when either end of synchronized block is reached or thread goes into waiting state. The lock is reentrant in the sense that the same thread can acquire the lock again and again but a different thread cannot. So synchronized keyword essentially guards a piece of code from being accessed by multiple threads simultaneously

Concurrency:

 collections are exactly opposite. They are called so because they allow multiple threads to concurrently access the same data (without causing a side effect). For example, concurrent Hash Map allows multiple threads to perform write operations in parallel as long as the writes are happening on different segments.


********************************************


2).


Message Passing Interface (MPI) is a communication protocol for parallel programming. MPI is specifically used to allow applications to run in parallel across a number of separate computers connected by a network

  In the MPI programming model, a computation comprises one or more   processes that communicate by calling library routines to send   and receive messages to other processes. In most MPI implementations, a fixed set of processes is created at program initialization, and one process is created per processor. However, these processes may execute different programs. Hence, the MPI programming model is sometimes referred to as multiple program multiple data (MPMD) to distinguish it from the SPMD model in which every processor   executes the same program.

Because the number of processes in an MPI computation is normally fixed, our focus in this chapter is on the mechanisms used to communicate   data between processes. Processes can use point-to-point communication operations to send a message from one named process to another; these operations can be used to implement local and unstructured communications. A group of processes can call collective communication operations to perform commonly used   global operations such as summation and broadcast. MPI's ability to probe for messages supports asynchronous communication. Probably MPI's most important feature from a software engineering viewpoint is its support for modular programming. A mechanism called a communicator allows the MPI programmer to define modules that encapsulate internal communication structures.



 


Comments

Post a Comment

Popular posts from this blog

Explain with the help of an example the distributed Coordination in OS?

  Definition   – In this article, we will fully  explain distributed operating system . Distributed operating system allows distributing of entire systems on the couples of center processors, and it serves on the multiple real time products as well as multiple users.   All processors are connected by valid communication medium such as high speed buses and telephone lines, and in which every  processor  contains own loca l  memory  along with other local processor. According this nature, distributed operating system is known as loosely coupled systems. This  operating system  involves multiple computers, nodes, and sites, and these components are linked each other with LAN/WAN lines. Distributed OS is capable for sharing their computational capacity and I/O files with allowing the virtual machine abstraction to users. Types of Distributed Operating System Classification of distributed operating system  Can be done in thr...
Read more

A BRIEF HISTORY OF COMPUERS:

Image
First Generation: Vacuum Tubes  ENIAC The ENIAC (Electronic Numerical Integrator And Computer), designed and constructed at the University of Pennsylvania, was the world’s first general-purpose electronic digital computer. The project was a response to U.S needs during World War II. John Mauchly, a professor of electrical engineering at the University of Pennsylvania, and John Eckert, one of his graduate students, proposed to build a general-purpose computer using vacuum tubes for the BRL’s application. In 1943, the Army accepted this proposal, and work began on the ENIAC. The resulting machine was enormous, weighing 30 tons, occupying 1500 square feet of floor space, and containing more than 18,000 vacuum tubes. When operating, it consumed 140 kilowatts of power. It was also substantially faster than any electromechanical computer, capable of 5000 additions per second. The ENIAC was completed in 1946, too late to be used in the war effort. The use of the ENIAC for a pur...
Read more

State the main difference in Microsoft windows GUI and MAC GUI?

  In present times, it is not uncommon to have a desktop with two or more monitors. How these operating systems perform in a multiple monitor environment is an interesting topic. In this work, we will evaluate the efficiency of and compare how two popular operating systems, Windows and Mac OS, perform in large and multiple monitor environments. In particular, we will evaluate the performance of menu bars in both operating systems as they serve a near identical purpose and have the same functionality while providing their offerings differently. It is well-known that Mac OS uses a menu bar at the top of the screen (global) and Windows uses a menu bar attached to the top of its respective application (local).  The conducted user study shows that the overall performance of Windows menu bar was better than that of the Mac menu bar implementation in the conducted tests .
Read more