java如何实现静态变量多线程安全问题


问题,如题!
我先说我目前的方案(我感觉不靠谱,但是又不知道如何测试):


 public class SaveDatabasePlanCache {

   private static Integer vehicleSum=0;

    public static Integer getVehicleSum() {
            return vehicleSum;
    }

    public synchronized static void  setVehicleSum(Integer vehicleSum) {
        SaveDatabasePlanCache.vehicleSum = vehicleSum;
    }

}

测试方案:


 TestThread t1=new TestThread("线程1: ");
        TestThread t2=new TestThread("线程2: ");
        TestThread t3=new TestThread("线程3: ");
        TestThread t4=new TestThread("线程4: ");

        ExecutorService service=Executors.newFixedThreadPool(4);
        service.submit(t1);
        service.submit(t2);
        service.submit(t3);
        service.submit(t4);

线程代码:


 public void run() {
                int sum=0;
                boolean flag=true;
                while(flag){
                    sum=SaveDatabasePlanCache.getVehicleSum();
                    if(sum==10000){
                        System.out.println(new Date().toLocaleString()+" "+title+"不执行");
                        flag=false;
                    }else{
                        SaveDatabasePlanCache.setVehicleSum(sum+1);
                        System.out.println(new Date().toLocaleString()+" "+title+SaveDatabasePlanCache.getVehicleSum());
                    }


                }

            }

上面是我对静态变量的线程安全方案,就是在设置值的时候开启一个线程同步锁的机制,不知道这样是否有效,我在测试的时候,程序死锁过。
请问有什么有效的方法可以测试吗或者解决我当前的问题,谢谢!

java java多线程 线程安全 静态方法 synchronized

费诺瓦.卡塔 9 years, 4 months ago

先找到死锁的原因,很明显应该在你的线程处理方法里。

dgwnb answered 9 years, 4 months ago

问题已经解决,我把缓存类的属性改为了原子数据类型代码如下:


 public static AtomicInteger vehicleSum=new AtomicInteger(0);
    public static AtomicInteger vehicleCurrent=new AtomicInteger(1);

    public static AtomicInteger vehicle32Sum=new AtomicInteger(0);
    public static AtomicInteger vehicle32Current=new AtomicInteger(1);

    public static AtomicInteger vehicle33Sum=new AtomicInteger(0);
    public static AtomicInteger vehicle33Current=new AtomicInteger(1);

    public static AtomicInteger vehicleWdSum=new AtomicInteger(0);
    public static AtomicInteger vehicleWdCurrent=new AtomicInteger(1);

    public static AtomicInteger vehicleZdSum=new AtomicInteger(0);
    public static AtomicInteger vehicleZdCurrent=new AtomicInteger(1);

么么艾萨克 answered 9 years, 4 months ago

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