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Презентация на тему 8. Java concurrency 1. Threads

Содержание

2. ConcurrencyA single application is often expected to
3. ProcessesA process has a self-contained execution environmentA
4. Threads IThreads are sometimes called lightweight processesBoth
5. Threads IIThreads share the process's resources, including
6. Defining a ThreadAn application that creates an
7. Runnable ObjectThe Runnable interface defines a single
8. Runnable Object Examplepublic class HelloRunnable implements Runnable
9. Runnable Object in Java 8public static void
10. Thread SubclassThe Thread class itself implements Runnable,
11. Thread Subclass Examplepublic class HelloThread extends Thread
12. Runnable vs Thread SubclassA Runnable object employment
13. Pausing Execution with SleepThread.sleep causes the current
14. Sleep Examplepublic class SleepMessages { public
15. Thread Race ExampleCreate two classes: first implements
16. Thread Race ExampleSee 811ThreadRace project for the full text.*InfopulseTraining Center
17. Thread TerminationsA thread terminates when:its run method
18. Interrupted StatusWhen the interrupt method is called
19. How to Check Interrupted StatusTo find out
20. InterruptedExceptionIf a thread is blocked, it cannot
21. InterruptedException Examplefor (int i = 0;
22. JoinsThe join method allows one thread to
23. Join ExerciseModify 811ThreadRace project so that first thread should wait for second thread finishing*InfopulseTraining Center
24. ThreadRace Classpublic static void main(String[] args) throws
25. Join ExerciseSee 812ThreadJoin project for the full text.*InfopulseTraining Center
26. Thread Prioritypublic final void setPriority(int newPriority) - changes the priority
27. Sharing Resources ExampleTry to generate Fibonacci series
28. Sharing Resources ExampleSee 813Resources project for the full text.*InfopulseTraining Center
29. Скачать презентацию
30. Похожие презентации

ConcurrencyA single application is often expected to do more than one thing at a timeSoftware that can do such things is known as concurrent softwareSince version 5.0, the Java platform has also included high-level concurrency APIs*InfopulseTraining

ProcessesA process has a self-contained execution environmentA process generally has a complete,

Threads IThreads are sometimes called lightweight processesBoth processes and threads provide an

Threads IIThreads share the process's resources, including memory and open filesFrom the

Defining a ThreadAn application that creates an instance of Thread must provide

Runnable ObjectThe Runnable interface defines a single method, run, meant to contain

Runnable Object Examplepublic class HelloRunnable implements Runnable { public void run()

Runnable Object in Java 8public static void main(String args[]) { Runnable r

Thread SubclassThe Thread class itself implements Runnable, though its run method does

Thread Subclass Examplepublic class HelloThread extends Thread { public void run()

Runnable vs Thread SubclassA Runnable object employment is more general, because the

Pausing Execution with SleepThread.sleep causes the current thread to suspend execution for

Sleep Examplepublic class SleepMessages { public static void main(String args[]) throws

Thread Race ExampleCreate two classes: first implements Runnable interface, and second extends

Thread Race ExampleSee 811ThreadRace project for the full text.*InfopulseTraining Center

Thread TerminationsA thread terminates when:its run method returns, by executing a return

Interrupted StatusWhen the interrupt method is called on a thread, the interrupted

How to Check Interrupted StatusTo find out whether the interrupted status was

InterruptedExceptionIf a thread is blocked, it cannot check the interrupted statusThis is

InterruptedException Examplefor (int i = 0; i < importantInfo.length; i++) {

JoinsThe join method allows one thread to wait for the completion of

Join ExerciseModify 811ThreadRace project so that first thread should wait for second thread finishing*InfopulseTraining Center

ThreadRace Classpublic static void main(String[] args) throws InterruptedException{ ThreadRunnab r = new ThreadRunnab(); Thread

Join ExerciseSee 812ThreadJoin project for the full text.*InfopulseTraining Center

Thread Prioritypublic final void setPriority(int newPriority) - changes the priority of this threadpublic final int getPriority() -

Sharing Resources ExampleTry to generate Fibonacci series in one thread and print

Sharing Resources ExampleSee 813Resources project for the full text.*InfopulseTraining Center

Manualshttp://docs.oracle.com/javase/tutorial/essential/concurrency/index.html*InfopulseTraining Center

Слайды презентации

Слайд 2 Concurrency
A single application is often expected to do

ConcurrencyA single application is often expected to do more than one

more than one thing at a time
Software that can

do such things is known as concurrent software
Since version 5.0, the Java platform has also included high-level concurrency APIs

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Слайд 3 Processes
A process has a self-contained execution environment
A process

ProcessesA process has a self-contained execution environmentA process generally has a

generally has a complete, private set of basic run-time

resources (e.g own memory space)
A Java application can create additional processes using a ProcessBuilder object.
Multiprocess applications are beyond the scope of this lesson

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Слайд 4 Threads I
Threads are sometimes called lightweight processes
Both processes

Threads IThreads are sometimes called lightweight processesBoth processes and threads provide

and threads provide an execution environment, but creating a

new thread requires fewer resources than creating a new process.
Threads exist within a process — every process has at least one thread

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Слайд 5 Threads II
Threads share the process's resources, including memory

Threads IIThreads share the process's resources, including memory and open filesFrom

and open files
From the application programmer's point of view,

you start with just one thread, called the main thread
This thread has the ability to create additional threads

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Слайд 6 Defining a Thread
An application that creates an instance

Defining a ThreadAn application that creates an instance of Thread must

of Thread must provide the code that will run

in that thread:
Provide a Runnable object.
Create Thread Subclass.

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Слайд 7 Runnable Object
The Runnable interface defines a single method,

Runnable ObjectThe Runnable interface defines a single method, run, meant to

run, meant to contain the code executed in the

thread
The Runnable object is passed to the Thread constructor
Thread’s start method is called

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Слайд 8 Runnable Object Example
public class HelloRunnable implements Runnable {

public void run() {

System.out.println("Hello from a thread!");
}
public static void main(String args[]) {
(new Thread(new HelloRunnable())).start();
}
}

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Слайд 9 Runnable Object in Java 8
public static void main(String

Runnable Object in Java 8public static void main(String args[]) { Runnable

args[]) {
Runnable r =
() -> System.out.println("Hello world!");

new Thread(r).start();
}

Слайд 10 Thread Subclass
The Thread class itself implements Runnable, though

Thread SubclassThe Thread class itself implements Runnable, though its run method

its run method does nothing
An application can subclass Thread,

providing its own implementation of run

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Слайд 11 Thread Subclass Example
public class HelloThread extends Thread {

public void run() { System.out.println("Hello

from a thread!");
}
public static void main(String args[]) { (new HelloThread()).start();
}
}

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Слайд 12 Runnable vs Thread Subclass
A Runnable object employment is

Runnable vs Thread SubclassA Runnable object employment is more general, because

more general, because the Runnable object can subclass a

class other than Thread
Thread subclassing is easier to use in simple applications, but is limited by the fact that your task class must be a descendant of Thread
A Runnable object is applicable to the high-level thread management APIs

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Слайд 13 Pausing Execution with Sleep
Thread.sleep causes the current thread

Pausing Execution with SleepThread.sleep causes the current thread to suspend execution

to suspend execution for a specified period
This is an

efficient means of making processor time available to the other threads of an application or other applications that might be running on a computer system
The sleep period can be terminated by interrupts

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Слайд 14 Sleep Example
public class SleepMessages {
public static

void main(String args[]) throws InterruptedException {

String importantInfo[] = { "Mares eat oats",
"Does eat oats", "Little lambs eat ivy",
"A kid will eat ivy too"};
for (int i = 0; i < importantInfo.length; i++) {
Thread.sleep(4000);
System.out.println(importantInfo[i]);
}
}
}

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Слайд 15 Thread Race Example
Create two classes: first implements Runnable

Thread Race ExampleCreate two classes: first implements Runnable interface, and second

interface, and second extends Thread class. Method run() in

both classes prints thread and iteration numbers and sleeps in some seconds.

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Слайд 16 Thread Race Example
See 811ThreadRace project for the full

text.

*
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Слайд 17 Thread Terminations
A thread terminates when:
its run method returns,

Thread TerminationsA thread terminates when:its run method returns, by executing a

by executing a return statement
after executing the last statement

in the method body
if an exception occurs that is not caught in the method
The interrupt method can be used to request termination of a thread

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Слайд 18 Interrupted Status
When the interrupt method is called on

Interrupted StatusWhen the interrupt method is called on a thread, the

a thread, the interrupted status of the thread is

set
This is a boolean flag that is present in every thread
Each thread should occasionally check whether it has been interrupted

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Слайд 19 How to Check Interrupted Status
To find out whether

How to Check Interrupted StatusTo find out whether the interrupted status

the interrupted status was set, first call the static

Thread.currentThread method to get the current thread and then call the isInterrupted method:
while (!Thread.currentThread().isInterrupted())
{
do more work
}

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Слайд 20 InterruptedException
If a thread is blocked, it cannot check

InterruptedExceptionIf a thread is blocked, it cannot check the interrupted statusThis

the interrupted status
This is where the InterruptedException comes in
When

the interrupt method is called on a thread that blocks on a call such as sleep or wait, the blocking call is terminated by an InterruptedException

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Слайд 21 InterruptedException Example
for (int i = 0; i

< importantInfo.length; i++) {
// Pause for 4

seconds
try { Thread.sleep(4000); }
catch (InterruptedException e) {
return;
}
System.out.println(importantInfo[i]);
}

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Слайд 22 Joins
The join method allows one thread to wait

JoinsThe join method allows one thread to wait for the completion

for the completion of another
If t is a Thread

object whose thread is currently executing, t.join() causes the current thread to pause execution until t's thread terminates
Overloads of join allow the programmer to specify a waiting period
join responds to an interrupt by exiting with an InterruptedException

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