10. Multithreading

10. Multithreading

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public class SumTest { public static void main(String a1[]) { int a, b, sum; a = Integer.parseInt(a1[0]); b = Integer.parseInt(a1[1]); sum = a + b ; // 두 수를 더하는 부분입니다 System.out.println(" 두수의 합은 " + sum + " 입니다 "); }}

JAVA

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Multiple threads on multiple CPUs

Multiple threads sharing a single CPU

Thread 3

Thread 2

Thread 1

Thread 3

Thread 2

Thread 1

• Threads Concept

10 장 . 다중 스레드 3

Thread Class- java.lang Package

Thread()Thread(String s)Thread(Runnable r)Thread(Runnable r, String s)

10 장 . 다중 스레드

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MethodMethod Description

static void sleep(long msec)throws InterruptedException

Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds, subject to the precision and accuracy of system timers and schedulers.

static void sleep(long msec, int nsec) throws InterruptedException

Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds plus the specified number of nanoseconds, subject to the precision and accuracy of system timers and schedulers.

String getName() Returns this thread's name.

void setName(String s) Changes the name of this thread to be equal to the argument name.

void start()Causes this thread to begin execution; the Java Virtual Machine calls the run method of this thread.

final int getPriority() Returns this thread's priority.

final void setPriority(int p) Changes the priority of this thread.

void join() throws InterruptedException Waits for this thread to die.

void run()If this thread was constructed using a separate Runnable run object, then that Runnable object's run method is called; otherwise, this method does nothing and returns.

void suspend() This method has been deprecated, as it is inherently deadlock-prone

void resume()This method exists solely for use with suspend(), which has been deprecated be-cause it is deadlock-prone

http://docs.oracle.com/javase/8/docs/api/java/lang/Thread.html


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StateMachine diagram


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Thread states- New

- Runnable(ready)

- Running(executing)

- Waiting

- Dead(finished)


Thread Class

class ThreadA extends Thread { ......... public void run() { .... } .......}

ThreadA ta = new ThreadA();ta.start();


Runnable Interface

class RunnableB extends Applet implements Runnable { ......... public void run() { ........ } ........}

public interface Runnable { public void run();}


Example

RunnableB rb = new RunnableB(); Thread tb = new Thread(rb);tb.start();

RunnableB rb = new RunnableB();new Thread(rb).start();

10 장 . 다중 스레드 10

Exercises

ThreadFromThread.java

01020304050607080910111213

class ThreadTest extends Thread { public void run() { for (int i=1 ; i<=10 ; i++) { System.out.println(“Java :" + i); } }}public class ThreadFromThread { public static void main(String args[]) { ThreadTest t = new ThreadTest(); t.start(); }}

10 장 . 다중 스레드 11

Java : 1

Java : 2

Java : 3

Java : 4

Java : 5

Java : 6

Java : 7

Java : 8

Java : 9

Java : 10

10 장 . 다중 스레드 12

Exercises

ThreadFromRunnable.java

0102030405060708091011121314

class RunnableTest implements Runnable { public void run() { for (int i=1 ; i<=10 ; i++) { System.out.println(“Java :" + i); } } }public class ThreadFromRunnable { public static void main(String args[]) { RunnableTest r = new RunnableTest(); Thread t = new Thread(r); t.start(); }}

10 장 . 다중 스레드 13

Java : 1

Java : 2

Java : 3

Java : 4

Java : 5

Java : 6

Java : 7

Java : 8

Java : 9

Java : 10

10 장 . 다중 스레드 14

ExercisesDoubleThread.java

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class ThreadTest1 extends Thread { public ThreadTest1(String str) { setName(str); } public void run() { for (int i=1 ; i<=10 ; i++) { System.out.println(i + getName()); } System.out.println(“End" + getName()); }}public class DoubleThread { public static void main(String args[]) { ThreadTest1 t1 = new ThreadTest1 (" : Thread1"); ThreadTest1 t2 = new ThreadTest1 (" : Thread2"); t1.start(); t2.start(); }}

10 장 . 다중 스레드 15

1: Thread11: Thread22: Thread12: Thread23: Thread13: Thread24: Thread14: Thread25: Thread15: Thread26: Thread16: Thread27: Thread17: Thread28: Thread18: Thread29: Thread19: Thread210: Thread110: Thread2 End: Thread1End: Thread2

10 장 . 다중 스레드 16

1: Thread21: Thread12: Thread22: Thread13: Thread23: Thread14: Thread24: Thread15: Thread25: Thread16: Thread26: Thread17: Thread27: Thread18: Thread28: Thread19: Thread29: Thread110: Thread210: Thread1 End: Thread2End: Thread1


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setPriority()- Changes the priority of this thread.

static final int MAX_PRIORITY ← priority : 10static final int MIN_PRIORITY ← priority : 1static final int NORM_PRIORITY ← priority : 5


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ExcercisesThreadPriority.java

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class PriorityTest extends Thread{

public PriorityTest(String str){

setName(str);

}

public void run(){

for(int i=1; i<=5; i++){

System.out.println( i + getName() + " Priority : "

+ getPriority() );

}

}

}


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ExcercisesThreadPriority.java

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class ThreadPriority {

public static void main(String args[]){

PriorityTest t1 = new PriorityTest(" : First Thread");

PriorityTest t2 = new PriorityTest(" : Second Thread");

PriorityTest t3 = new PriorityTest(" : Third Thread");

int priority_t1 = Integer.parseInt(args[0]);

int priority_t2 = Integer.parseInt(args[1]);

t1.setPriority(priority_t1);

t2.setPriority(priority_t2);

t3.setPriority(Thread.MIN_PRIORITY);

t1.start();

t2.start();

t3.start();

}

}


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1 : Third Thread : 11 : First Thread : 51 : Second Thread : 102 : Second Thread : 103 : Second Thread : 104 : Second Thread : 102 : First Thread : 53 : First Thread : 54 : First Thread : 55 : First Thread : 52 : Third Thread : 15 : Second Thread : 103 : Third Thread : 14 : Third Thread : 15 : Third Thread : 1


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실습예제DoubleThread1.java

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class DoubleThreadTest1 extends Thread {

public DoubleThreadTest1(String str) {

setName(str);

}

public void run() {

for (int i=1 ; i<=3 ; i++) {

System.out.println(i + getName());

}

System.out.println(“End" + getName());

}

}

public class DoubleThread1 {

public static void main(String args[]) {

DoubleThreadTest1 t1 =

new DoubleThreadTest1(" : Thread1");

DoubleThreadTest1 t2 =


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new DoubleThreadTest1(" : Thread2");

System.out.println("***** Start *****");

t1.start();

t2.start();

System.out.println("***** End *****");

}

}


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***** Start ********** End *****1 : Thread21 : Thread12 : Thread22 : Thread13 : Thread23 : Thread1End : Thread2End : Thread1


5 스레드의 시작과 종료

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class DoubleThreadTest2 extends Thread {

public DoubleThreadTest2(String str) {

setName(str);

}

public void run() {

for (int i=1 ; i<=3 ; i++) {

System.out.println(i + getName());

}

System.out.println(“End" + getName());

}

}

public class DoubleThread2 {

public static void main(String args[])throws Exception {

DoubleThreadTest2 t1 = new DoubleThreadTest2

(" : Thread1");

DoubleThreadTest2 t2 = new DoubleThreadTest2


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(" : Thread2");

System.out.println("***** Start *****");

t1.start();

t2.start();

t1.join();

t2.join();

System.out.println("***** End *****");

}

}


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***** Start *****1 : Thread11 : Thread22 : Thread12 : Thread23 : Thread13 : Thread2End : Thread1End : Thread2***** End *****


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synchronized Method

329 page

Critical section

Critical section

unlock


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330 page


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ExcercisesTVContribution.java

010203040506070809101112131415161718

class Account { private int total = 0; synchronized void deposit() { total = total + 1000; } int gettotal() { return total; }}class Customer extends Thread { Account same_a; Customer(Account a, String s) { same_a = a; setName(s); } public void run() { for(int i = 0; i < 200 ; i++) { System.out.println(getName() + " : " + i);


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실습예제TVContribution.java

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same_a.deposit(); if (same_a.gettotal() >= 500000) break; } }}public class TVContribution { public static void main(String args[])throws Exception { Account same_account = new Account(); Customer donator1 = new Customer(same_account,“Donator1"); Customer donator2 = new Customer(same_account,"Donator2"); Customer donator3 = new Customer(same_account,"Donator3"); Customer donator4 = new Customer(same_account,"Donator4"); Customer donator5 = new Customer(same_account,"Donator5");


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실습예제TVContribution.java

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donator1.start(); donator2.start(); donator3.start(); donator4.start(); donator5.start(); donator1.join(); donator2.join(); donator3.join(); donator4.join(); donator5.join(); System.out.println(“Total : " + same_account.gettotal()); }}


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Donator3 : 0Donator3 : 1Donator1 : 0Donator4 : 0 .........Donator5 : 62Donator3 : 124Donator1 : 126Donator4 : 125Donator2 : 62Total : 504000


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Donator1 : 0Donator1 : 1Donator1 : 2Donator3 : 0 .........Donator2 : 42Donator3 : 102Donator5 : 92Donator1 : 62Donator2 : 43Total : 503000


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java.lang.Object Class

- wait(), notify(), notifyAll()

void wait() throws InterruptedExceptionvoid wait(long msec) throws InterruptedExceptionvoid wait(long msec, int nsec) throws InterruptedException

void notify()void notifyAll()


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wait( ), notify( ), notifyAll( ) Method

335 page


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ExcercisesProducerConsumer.java

0102030405060708091011121314151617181920

class Buffer { private int contents; private boolean available = false; public synchronized void put(int value) { while (available == true ) { try{ wait(); } catch (InterruptedException e) {} } contents = value; System.out.println (“Producer########## : Produce " + contents); notify(); available = true; }public synchronized int get() { while (available == false ) { try { wait();


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} catch (InterruptedException e) {} } System.out.println (“Consumer########## : Consume " + contents); notify(); available = false; return contents; } }class Producer extends Thread { private Buffer b; public Producer(Buffer blank) { b = blank ; } public void run() { for (int i = 1; i <= 10;i++) b.put(i); }}


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class Consumer extends Thread { private Buffer b; public Consumer(Buffer blank) { b = blank; } public void run() { int value = 0; for (int i = 1 ; i <= 10 ; i++ ) value = b.get(); }}public class ProducerConsumer { public static void main(String args[]) { Buffer buff = new Buffer(); Producer p1 = new Producer(buff); Consumer c1 = new Consumer(buff); p1.start() ; c1.start() ; }}


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Producer ########## : Produce 0Consumer########## : Consume 0Producer ########## : Produce 1

............................

Consumer########## : Consume 7 Producer ########## : Produce 8 Consumer########## : Consume 8 Producer ########## : Produce 9 Consumer########## : Consume 9

Documents

10. Multithreading