当使用start函数启动线程run之后，如果run线程里的程序没有运行完就再次使用start函数开启同一个run线程，那我想请问上一次的run线程会出现什么样的结果，是被打断还是等继续运行完之后再执行第二次调用?
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void QThread::start ( Priority priority = InheritPriority ) [slot]
Begins execution of the thread by calling run(), which should be reimplemented in a QThread subclass to contain your code. The operating system will schedule the thread according to the priority parameter. If the thread is already running, this function does nothing.