HotSpot虚拟机关于垃圾回收的几个问题
假如from-survivor space有些对象达到晋升到老年代的条件，而且老年代有足够的空间。
那么当Minor GC发生时：
1、from-survivor space那些达到晋升条件的对象什么时候会进入老年代；
2、Eden space和from-survivor space的对象何时进入to-survivor space，进入时是否有优先级；
3、如果to-survivor space空间不足时剩余的对象如何处理；
4、整个过程的执行顺序是什么。
HotSpot virtual machine on garbage collection of several issues
If from-survivor space some objects to reach the conditions of the old generation, and the old generation has enough space.
Then when the Minor GC occurs:
1) from-survivor space Those who reach the conditions of promotion when the object will into the old age;
2) Eden space and from-survivor space when the object into the to-survivor space, whether there is priority to enter;
3) If the to-survivor space fills up, remaining objects will be how to deal with;
4) what is the order of the whole process.
