Archive for: September, 2014

Synchronization

Synchronization Because multithreading introduces an asynchronous behavior to your programs, there must be a way for you to enforce synchronicity when you need it. For example, if you want two threads to communicate and share a complicated data structure, such as a linked list, you need some way to ensure that they don’t conflict with each other. That is,…

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Messaging

Messaging After you divide your program into separate threads, you need to define how they will communicate with each other. WheN programming with most other languages, you must depend on the operating system to establish communication between threads. This, of course, adds overhead. By contrast, Java Provides o clean. low-cost way for two or more threads to talk to…

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The Thread Class and the Runnable Interface

The Thread Class and the Runnable Interface Java’s multithreading system is built upon the Thread class, its methods, and its companion interface, Runnable. Thread encapsulates a thread of execution. Since you can’t directly refer to the ethereal state of a running thread, you will deal with it through its proxy, the Thread instance that spawned it. To create…

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The Main Thread

The Main Thread When a Java program starts up, one thrc~d begins running immediately. This is usually called the main thread of your program, because it is the one that is executed when your program begins. The main thread is important for two’ reasons: . • It is the thread from which other “child” threads will be…

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Creating a’Thread

Creating a’Thread In the most general sense, you’ create a thread.by instantiating an object of type Thread. Java defines two ways in which this can be’ accomplished: • You can implement the Runnable interface. • You can extend the Thread class, itself. The following two sections look at each method’, in turn. Implementing Runnable The easiest…

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Extending Thread

Extending Thread The second way to create a thread is to create a new class that extends Thread, and then to create an instance of that lass, The extending class must override the rune I method, which is the entry point fa the new thread, It must also call start to begin execution of the new thread, Here…

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Choosing an Approach ,

Choosing an Approach   At this point, you .might be wondering why Java has two ways to create child .threads and which approach is better. The answers to these questions turn on the same point.  The Thread class defines several methods that can be overridden by a derived class. Of these methods, the only one that must be…

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Creating Multiple Threads

Creating Multiple Threads So far, you have been using only two threads the main thread and. one child thread. However, your program can spawn as many threads as it needs. For example, the following program creates three child threads: The output from-this program is shown here: New thread:                  Thread…

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Using is Alive ( )and Join ( )

Using is Alive ( )and Join ( ) As mentioned, the main thread must be the last thread to finish. In the preceding examples, this is accomplished by calling sleep( ) within maine ), with a long enough delay to ensure that all child threads terminate prior to the main thread. However, this is hardly a satisfactory solution,…

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Thread priorities

Thread priorities   Thread priorities are used by the thread scheduler to decide when each thread should be allowed to run. In theory, higher-priority threads get more CPU time than lower-priority threads. In practice, the amount of CPU time that a thread gets often depends on several factors besides-its priority. (For example, how an operating system implements multitasking can affect…

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