[자바/SCJP/JAVA]자바 프로그래밍 - 라운드 로빈 스케쥴러

김윤석 2007. 12. 18. 14:27

자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA 자바/SCJP/JAVA

RoundRobin 방식으로 스케쥴링하기

CircularList.java 파일
   1 public class CircularList {
   2    Node head, nil;
   3    Node current;
   4
   5    public CircularList() {
   6    head = null;
   7    nil = null;
   8    current = null;
   9    }
10
11    public synchronized Object getNext() {
12    if(current == null) {
13    current = head;
14    } else {
15    current = current.next;
16    }
17    if(current == null) {
18    current = head;
19    }
20    if(current != null)
21    return current.value;
22    else
23    return null;
24    }
25
26    public synchronized void insert(Object o) {
27    if(head == null) {
28    Node node = new Node(o);
29    head = node;
30    nil = node;
31    } else {
32    Node node = new Node(o);
33    Node temp = nil;
34    nil = node;
35    temp.next = nil;
36    }
37    }
38
39    public void delete(Object o) {
40    Node temp1 = head;
41    Node temp2 = null;
42
43    while(temp1 != null) {
44    if(temp1.value == o) {
45    if(temp2 == null) {
46    head = temp1.next;
47    } else {
48    temp2.next = temp1.next;
49    }
50    break;
51    }
52    temp2 = temp1;
53    temp1 = temp1.next;
54    }
55    }
56
57    public class Node {
58    Object value;
59    Node next;
60
61    public Node(Object o) {
62    value = o;
63    next = null;
64    }
65    }
66 }

Scheduler.java 파일
   1 public class Scheduler extends Thread {
   2    private int timeslice;
   3    static private CircularList threads;
   4
   5    static {
   6    threads = new CircularList();
   7    }
   8
   9    public Scheduler(int t) {
10    timeslice = t;
11    setDaemon(true);
12    start();
13    }
14
15    static public void addThread(Thread t) {
16    threads.insert(t);
17    System.out.println("new thread inserted");
18    t.setPriority(2);
19    }
20
21    static public void removeThread(Thread t) {
22    if(t.isAlive())
23    t.setPriority(5);
24    threads.delete(t);
25    }
26
27    public void run() {
28    Thread current;
29    setPriority(6);
30    while(true) {
31    current = (Thread) threads.getNext();
32    if(current == null) {
33    System.out.println("Scheduling is done...");
34    continue;
35    }
36    if(current.isAlive()) {
37    current.setPriority(4);
38    } else {
39    removeThread(current);
40    }
41    //System.out.println("Scheduler running");
42    try {
43    Thread.sleep(timeslice);
44    } catch (InterruptedException ie) {
45    System.out.println("Thread interrupted.");
46    }
47    if(current.isAlive()) {
48    current.setPriority(2);
49    } else {
50    removeThread(current);
51    }
52    }
53    }
54 }

Task.java 파일
   1 class Task extends Thread {
   2    String id;
   3
   4    public Task(String s) {
   5    id = s;
   6    Scheduler.addThread(this);
   7    }
   8
   9    public void run() {
10    for(int i =0; i < 10 ; i++) {
11    doCalc(i);
12    System.out.println(id+":"+getPriority());
13    }
14    }
15
16    public void doCalc(int n) {
17    for(int i = 0; i < n*200000; i++)
18    ;
19    }
20 }

App.java 파일
   1 class App {
   2    public static void main(String args[]) {
   3    Task t1, t2, t3;
   4    Scheduler c = new Scheduler(100);
   5    t1 = new Task("T1");
   6    t2 = new Task("T2");
   7    t3 = new Task3("T3");
   8
   9    t1.start();
10    t2.start();
11    t3.start();
12    }
13 }
14
15 class Task3 extends Task {
16
17    public Task3(String id) {
18    super(id);
19    }
20
21    public void run() {
22    for(int i =0; i < 10 ; i++) {
23    doCalc(i);
24    System.out.println("Task3 id ="+id + ":"+getPriority());
25    }
26    }
27
28    public void doCalc(int n) {
29    for(int i = 0; i < n*200000; i++)
30    ;
31    }
32
33 }

결과
% java App
new thread inserted
new thread inserted
new thread inserted
T1:4
T2:4
T2:4
Task3 id =T3:4
Task3 id =T3:4
T1:4
T2:4
Task3 id =T3:4
T1:4
T2:4
Task3 id =T3:4
T1:4
T1:4
T2:4
Task3 id =T3:4
T1:4
T2:4
Task3 id =T3:4
T1:4
T2:4
Task3 id =T3:4
T1:4
T2:4
Task3 id =T3:4
Task3 id =T3:4
T1:4
T2:4
T1:4
T2:4
Task3 id =T3:2

추천학원:

http://www.it-bank.or.kr/prom/java_main.htm