现在我编写了一个Java程序,其目的是检测死锁并从这种情况中恢复。程序输入是两个数字,N =资源类型数,M =进程数。
我想做这样的事情:
private static void test2() {
final ReentrantLock lock1 = new ReentrantLock();
final ReentrantLock lock2 = new ReentrantLock();
Thread thread1 = new Thread(new Runnable() {
@Override public void run() {
try {
lock1.lock();
System.out.println("Thread1 acquired lock1");
try {
TimeUnit.MILLISECONDS.sleep(50);
} catch (InterruptedException ignore) {}
lock2.lock();
System.out.println("Thread1 acquired lock2");
}
finally {
lock2.unlock();
lock1.unlock();
}
}
});
thread1.start();
Thread thread2 = new Thread(new Runnable() {
@Override public void run() {
try {
lock2.lock();
System.out.println("Thread2 acquired lock2");
try {
TimeUnit.MILLISECONDS.sleep(50);
} catch (InterruptedException ignore) {}
lock1.lock();
System.out.println("Thread2 acquired lock1");
}
finally {
lock1.unlock();
lock2.unlock();
}
}
});
thread2.start();
// Wait a little for threads to deadlock.
try {
TimeUnit.MILLISECONDS.sleep(100);
} catch (InterruptedException ignore) {}
detectDeadlock();
}
但不是2,N锁定,我有几个问题这样做。我的代码在这里尝试:
class Main {
private static int MAX_AVAILABLE = 10;
private static int IDLE = 1000;
public static void main(String[] args) throws java.lang.Exception{
int n, m; //number of resources and process, respectively
ReentrantLock[] resources; // Locks for resources
int[] available; // Number of instances per resource
Process[] processes; // Processes array
DeadlockDetector supervisor; // Deadlock detaction class
n = Integer.valueOf(args[0]);
m = Integer.valueOf(args[1]);
resources = new ReentrantLock[n];
available = new int[n];
processes = new Process[m];
supervisor = new DeadlockDetector();
// Create resources array
for(int i=0; i<n; ++i){
available[i] = (int)(Math.floor(Math.random()*MAX_AVAILABLE + 1));
resources[i] = new ReentrantLock();
System.out.println("R"+String.valueOf(i+1)+"-> instances: "+String.valueOf(available[i]));
}
// Creating processes
for(int i=0; i<m; ++i){
processes[i] = new Process(i, resources, available, n);
System.out.println("P"+String.valueOf(i+1)+"-> requested "+Arrays.toString(processes[i].requested));
processes[i].start();
}
//Run deadlock detection
try {
TimeUnit.MILLISECONDS.sleep(IDLE);
}catch (InterruptedException ignore){}
supervisor.start();
}
}
class Process extends Thread{
public int id;
public int total; // Total of resources instances needed for finished the process
public ReentrantLock[] resources;
public int[] requested; // Number of instances needed per resource type
public boolean[] needed; // Boolean indicating whether the process needs at least one instance of the resource i
public int n;
private static int MIN_TIME = 1000;
private static int MAX_TIME = 3000;
public Process(int index, ReentrantLock[] res, int[] available, int n_resources){
id = index;
n = n_resources;
resources = res;
total = 0;
requested = new int[n];
needed = new boolean[n];
for(int i=0; i<n; ++i){
requested[i] = (int)(Math.floor(Math.random()*available[i]));
needed[i] = requested[i] > 0;
total += requested[i];
}
}
@Override
public void run(){
int resourceT = 0;
int timeToSleep;
System.out.println("P"+String.valueOf(id+1)+" begin running");
try{
while(total > 0){
resourceT = (int)(Math.floor(Math.random()*n));
if(requested[resourceT] < 1){
System.out.println("P"+String.valueOf(id+1)+"-> I do not need more R"+String.valueOf(resourceT+1));
continue;
}
System.out.println("P"+String.valueOf(id+1)+"-> I'll take R"+String.valueOf(resourceT+1));
resources[resourceT].lock();
timeToSleep = (int)(Math.floor(Math.random()*(MAX_TIME - MIN_TIME)) + MIN_TIME);
try{
TimeUnit.MILLISECONDS.sleep(timeToSleep);
}catch (InterruptedException ignore){}
--total;
--requested[resourceT];
}
}finally{
for(int i=0; i<n; ++i){
if(needed[i] && resources[i].isHeldByCurrentThread())
resources[i].unlock();
}
}
System.out.println("P"+String.valueOf(id+1)+"-> Im finished");
}
}
class DeadlockDetector extends Thread{
public ThreadMXBean threadBean;
public long[] threadIds;
public DeadlockDetector(){
}
@Override
public void run(){
Boolean good;
this.threadBean = ManagementFactory.getThreadMXBean();
threadIds = threadBean.findDeadlockedThreads();
int deadlockedThreads = threadIds != null? threadIds.length : 0;
if(deadlockedThreads>1){
good = false;
System.out.println("Number of deadlocked threads: " + deadlockedThreads);
//recoverDeadlock();
//break;
}
}
public void recoverDeadlock(){
}
}
拜托,有人可以帮我修复这个细节吗?谢谢!