java - 世代垃圾收集

Question

据我了解，分代GC将对象分成几代。
并且在每个周期中，GC 只运行一代。

为什么？为什么垃圾收集只有一代就足够了？

P.S: 我从 here 了解所有这些.

Answer 1

如果您阅读 link我在 earlier question you had about Generational GC 中提供，你就会明白为什么会这样了，这个循环就是white set内存被填满的时候。

To optimize for this scenario, memory is managed in generations, or memory pools holding objects of different ages. Garbage collection occurs in each generation when the generation fills up. Objects are allocated in a generation for younger objects or the young generation, and because of infant mortality most objects die there. When the young generation fills up it causes a minor collection. Minor collections can be optimized assuming a high infant mortality rate. The costs of such collections are, to the first order, proportional to the number of live objects being collected. A young generation full of dead objects is collected very quickly. Some surviving objects are moved to a tenured generation. When the tenured generation needs to be collected there is a major collection that is often much slower because it involves all live objects.

基本上，每个对象都分为几代(基于关于对象的假设)并将它们放入特定代的内存堆中。当该内存堆被填满时，GC 周期开始，那些仍然引用的对象被移动到另一个内存堆并添加新对象。