程序并非总能终止？多线程测试场景下的技术咨询

我正为个人项目测试多线程功能，同时尝试开发异常应对方案，于是写了如下测试代码：

public class main {
    static int addToCounter;
    static int addToErrorCounter;

    public static void main(String[] args) throws InterruptedException {
        int threads = 10;
        Executor exec = new Executor();
        for (int i = 0; i < threads; i++) {
            double error = Math.random();
            testClass aldo = new testClass();
            Thread thread = aldo.getThread(300, error);
            exec...
        }
    }
}

内容的提问来源于stack exchange，提问作者user9549355