小编sss*_*sss的帖子

我想通过使用乐观锁定来处理并发执行.我@Version在我的实体类中包含了注释.

在我的代码中,我同时运行两个线程.有时它正确执行.有时它是投掷org.eclipse.persistence.exceptions.OptimisticLockException和javax.persistence.OptimisticLockException.

public class StudentCreation implements Runnable {
    EntityManagerFactory emf = 
        Persistence.createEntityManagerFactory("jpaApp");
    Student student = null;

    @Override
    public void run() {
        for (int i = 1; i <= 2; i++) {
            try {
                if (i % 2 == 0) {
                    update("XYZ");
                } else {
                    update("ABC");
                }
            } catch (Exception e) {
                System.out.println("Update exception");
            }
        }
    }

    // main method
    public static void main(String ar[]) {
        StudentCreation std1 = new StudentCreation();
        // creating two threads …