java实现死锁避免银行家算法
时间: 2023-06-28 10:11:28 浏览: 54
银行家算法是一种避免死锁的经典算法,它主要用于分配有限的资源,以避免出现死锁的情况。下面是Java实现死锁避免银行家算法的示例代码:
```java
import java.util.Scanner;
public class BankerAlgorithm {
private int[][] need; // 还需要的各类资源
private int[][] allocate; // 已分配的各类资源
private int[] available; // 可用的各类资源
private int[] safeSequence; // 安全序列
public void init() {
Scanner scanner = new Scanner(System.in);
System.out.println("请输入进程数量:");
int processCount = scanner.nextInt();
System.out.println("请输入资源种类数量:");
int resourceCount = scanner.nextInt();
need = new int[processCount][resourceCount];
allocate = new int[processCount][resourceCount];
available = new int[resourceCount];
safeSequence = new int[processCount];
System.out.println("请输入每个进程需要的各类资源:");
for (int i = 0; i < processCount; i++) {
for (int j = 0; j < resourceCount; j++) {
need[i][j] = scanner.nextInt();
}
}
System.out.println("请输入每个进程已分配的各类资源:");
for (int i = 0; i < processCount; i++) {
for (int j = 0; j < resourceCount; j++) {
allocate[i][j] = scanner.nextInt();
}
}
System.out.println("请输入系统可用的各类资源:");
for (int i = 0; i < resourceCount; i++) {
available[i] = scanner.nextInt();
}
}
public void run() {
int processCount = need.length;
int resourceCount = available.length;
int[] work = new int[resourceCount];
System.arraycopy(available, 0, work, 0, resourceCount);
boolean[] finish = new boolean[processCount];
for (int i = 0; i < processCount; i++) {
finish[i] = false;
}
int count = 0;
while (count < processCount) {
boolean found = false;
for (int i = 0; i < processCount; i++) {
if (!finish[i]) {
boolean enough = true;
for (int j = 0; j < resourceCount; j++) {
if (need[i][j] > work[j]) {
enough = false;
break;
}
}
if (enough) {
safeSequence[count] = i;
count++;
finish[i] = true;
found = true;
for (int j = 0; j < resourceCount; j++) {
work[j] += allocate[i][j];
}
}
}
}
if (!found) {
System.out.println("系统处于不安全状态,无法分配资源!");
return;
}
}
System.out.println("安全序列:");
for (int i = 0; i < processCount; i++) {
System.out.print("P" + safeSequence[i]);
if (i != processCount - 1) {
System.out.print(" -> ");
}
}
System.out.println();
}
public static void main(String[] args) {
BankerAlgorithm bankerAlgorithm = new BankerAlgorithm();
bankerAlgorithm.init();
bankerAlgorithm.run();
}
}
```
在这个示例代码中,我们通过输入进程数量、资源种类数量、每个进程需要的各类资源、每个进程已分配的各类资源、系统可用的各类资源来初始化我们的银行家算法。接着,我们通过遍历所有进程来找到一个安全的序列。如果无法找到一个安全的序列,则说明当前系统处于不安全状态,无法分配资源。如果找到了一个安全的序列,则输出这个序列。