进程调度：时间片轮转+抢占+动态优先级调度算法

优先级调度算法"/>

进程调度：时间片轮转+抢占+动态优先级调度算法

时间片轮转：每个进程至多持续运行一定时间。

抢占：进程进入就绪队列，进行优先级比较，优先级大的可抢占正在运行的进程。

动态优先级：进程进入就绪队列一定时间未获取cpu，则提升优先级。

进程类

package process;/*** 进程类*/
public class Process implements Comparable<Process>{//  进程标识管理器private static int processIdManage = 1;//  进程大小private int size;//  进程控制块private Pcb pcb;//  进程优先级更新时间条件private long priorityUpdateCondition;public Process(int size){this.size = size;this.pcb = new Pcb();}public int getSize() {return size;}public long getPriorityUpdateCondition() {return priorityUpdateCondition;}public void setPriorityUpdateCondition(long priorityUpdateCondition) {this.priorityUpdateCondition = priorityUpdateCondition;}@Overridepublic int compareTo(Process o) {//  通过优先级实现进程比较return -(this.getPcb().getPriority() - o.getPcb().getPriority());}/*** 进程控制块类*/public static class Pcb{//  进程标识private int id;//  进程状态private String status;//  进程优先级private int priority;//  进程运行至结束需要的时间private long needRunTime;//  进程等待时间private long waitRunTotalTime;public Pcb(){this.id = processIdManage++;this.status = "创建";this.priority = 0;this.needRunTime = 0;this.waitRunTotalTime = 0;}public int getId(){return id;}public String getStatus() {return status;}public void setStatus(String status) {this.status = status;}public int getPriority() {return priority;}public long getNeedRunTime() {return needRunTime;}public void setNeedRunTime(long needRunTime) {this.needRunTime = needRunTime;}public void setPriority(int priority){this.priority = priority;}public long getWaitRunTotalTime() {return waitRunTotalTime;}public void setWaitRunTotalTime(long waitRunTotalTime) {this.waitRunTotalTime = waitRunTotalTime;}}public Pcb getPcb() {return pcb;}}

调度类

package process;import java.util.ArrayList;
import java.util.Collections;
import java.util.List;/*** 进程调度类*/
public class ProcessDispatch {//  就绪队列private final static List<Process> PROCESS_QUEUE = new ArrayList<Process>();//  优先级更新条件：50秒不被调度则更新private static long condition = 50;/*** 添加进程进入就绪队列，更改进程状态为:就绪* @param process 进程* @return boolean 添加成功返回true,否则false*/public synchronized static boolean add(Process process){if(process == null)return false;process.getPcb().setStatus("就绪");PROCESS_QUEUE.add(process);showStatus(process);//  更新队列顺序Collections.sort(PROCESS_QUEUE);return true;}/*** 抢占cpu，更改进程状态为:运行* @return Process 抢占的进程*/private synchronized static Process removeTop(){if(PROCESS_QUEUE.isEmpty()){return null;}Process process = PROCESS_QUEUE.remove(0);process.getPcb().setStatus("运行");process.setPriorityUpdateCondition(0);showStatus(process);return process;}/*** 显示进程状态* @param process 进程*/private synchronized static void showStatus(Process process){if(process == null)return;Process.Pcb pcb = process.getPcb();System.out.printf("进程Id:%5d 进程优先级:%5d 进程状态:%6s 剩余需运行时间:%5d 等待时间:%5d\n",pcb.getId(),pcb.getPriority(),pcb.getStatus(),pcb.getNeedRunTime(),pcb.getWaitRunTotalTime());}/*** 获得就绪队列第一个进程* @return Process 进程*/private synchronized static Process getTop(){if(PROCESS_QUEUE.isEmpty()){return null;}return PROCESS_QUEUE.get(0);}/*** 更新进程等待时间，并判断是否更新优先级*/private synchronized static void addWaitTimeAndUpdatePriority(){boolean isUpdate = false;for(Process p:PROCESS_QUEUE){//  更新进程优先级更新时间条件p.setPriorityUpdateCondition(p.getPriorityUpdateCondition()+1);Process.Pcb pcb = p.getPcb();//  更新总的等待时间pcb.setWaitRunTotalTime(pcb.getWaitRunTotalTime()+1);//  增加进程优先级if(p.getPriorityUpdateCondition() == condition){isUpdate = true;pcb.setPriority(pcb.getPriority()+1);}}//  优先级更新，进行重新排序队列if(isUpdate)Collections.sort(PROCESS_QUEUE);}/*** 时间片管理类*/protected static class TimeSliceManage implements Runnable{//  时间片大小为5private static long size = 5-1;//  开始时间private static long start;//  当前时间private static long stop;//  cpu进程private static Process cpuProcess;public void setSize(long size){TimeSliceManage.size = size;}@Overridepublic void run(){start = stop = 0;while(true){stop++;//  如果没有进程运行if(cpuProcess == null){start = stop = 0;cpuProcess = removeTop();continue;}long intervalSize = stop - start;Process.Pcb pcb = cpuProcess.getPcb();//  时间片用完if(intervalSize == size){//  进程未运行结束if(pcb.getNeedRunTime() > 1){//  更新运行时间pcb.setNeedRunTime(pcb.getNeedRunTime()-1);showStatus(cpuProcess);//  更换时间片,将cpu进程添加到就绪队列add(cpuProcess);//  就绪进程抢占cpucpuProcess = removeTop();//  进程运行结束}else{pcb.setStatus("结束");pcb.setNeedRunTime(0);showStatus(cpuProcess);//  更换时间片cpuProcess = removeTop();}start = stop = 0;//  时间片未用完}else{//  进程未运行结束if(pcb.getNeedRunTime() > 1){//  更新运行时间pcb.setNeedRunTime(pcb.getNeedRunTime()-1);showStatus(cpuProcess);//  就绪队列最高优先级进程 可抢占 当前cpu进程Process topProcess = getTop();if(topProcess != null && topProcess.getPcb().getPriority() > pcb.getPriority()){//  更换时间片,将cpu进程添加到就绪队列add(cpuProcess);//  就绪进程抢占cpucpuProcess = removeTop();start = stop = 0;}//  进程运行结束}else{pcb.setStatus("结束");pcb.setNeedRunTime(0);showStatus(cpuProcess);//  更换时间片cpuProcess = removeTop();start = stop = 0;}}//  就绪队列所有进程等待时间+1addWaitTimeAndUpdatePriority();}}}//  时间片线程对象private static Thread thread = new Thread(new TimeSliceManage());//  启动时间片public static void startTimeSlice(){thread.start();}//  停止时间片public static void stopTimeSlice(){thread.hashCode();}
}

Test类

package process;public class Test {public static void main(String[] args) {ProcessDispatch.startTimeSlice();Process p1 = new Process(2000);p1.getPcb().setNeedRunTime(20);Process p2 = new Process(150);p2.getPcb().setNeedRunTime(10);p2.getPcb().setPriority(1);Process p3 = new Process(300);p3.getPcb().setNeedRunTime(30);p3.getPcb().setPriority(1);Process p4 = new Process(1000);p4.getPcb().setNeedRunTime(20);p4.getPcb().setPriority(1);ProcessDispatch.add(p1);ProcessDispatch.add(p2);ProcessDispatch.add(p3);ProcessDispatch.add(p4);while (true);}
}

结果演示