接近两个月左右没有写博客，主要是因为小孩过来后，回家比较忙，现在小孩端午送回家了，开始继续之前的JVM学习之路，前面学习了GC的算法和种类，那么本章则是基于算法来产生实际的用途，即垃圾收集器。
一、堆的回顾
新生代中的98%对象都是“朝生夕死”的，所以并不需要按照1:1的比例来划分内存空间，而是将内存分为一块比较大的Eden空间和两块较小的Survivor空间，每次使用Eden和其中一块Survivor。当回收时，将Eden和Survivor中还存活着的对象一次性地复制到另外一块Survivor空间上，最后清理掉Eden和刚才用过的Survivor空间。HotSpot虚拟机默认Eden和Survivor的大小比例是8:1，也就是说，每次新生代中可用内存空间为整个新生代容量的90%（80%+10%），只有10%的空间会被浪费。
当然，98%的对象可回收只是一般场景下的数据，我们没有办法保证每次回收都只有不多于10%的对象存活，当Survivor空间不够用时，需要依赖于老年代进行分配担保，所以大对象直接进入老年代。
堆的结构如下图所示：
http://test.baidu.com/qss/8541/503559.html
http://test.baidu.com/qss/27aa/503580.html
http://test.baidu.com/qss/f245/503585.html
http://test.baidu.com/qss/8771/503590.html
http://test.baidu.com/qss/50fb/503604.html
http://test.baidu.com/qss/a5a2/503608.html
http://test.baidu.com/qss/01f3/503617.html
http://test.baidu.com/qss/032d/503626.html
http://test.baidu.com/qss/71eb/503633.html
http://test.baidu.com/qss/bd53/503641.html
http://test.baidu.com/qss/ec3b/503646.html
http://test.baidu.com/qss/275d/503650.html
http://test.baidu.com/qss/3a4e/503665.html
http://test.baidu.com/qss/9d3a/503719.html
http://test.baidu.com/qss/3e27/503788.html
http://test.baidu.com/qss/8e02/503906.html
http://test.baidu.com/qss/dfa7/503966.html
http://test.baidu.com/qss/d53d/504042.html
http://test.baidu.com/qss/0eac/504128.html
http://test.baidu.com/qss/c4c0/504201.html
http://test.baidu.com/qss/918a/504369.html
http://test.baidu.com/qss/8c8a/504472.html
http://test.baidu.com/qss/69c2/504576.html
http://test.baidu.com/qss/0b7e/504680.html
http://test.baidu.com/qss/0578/504790.html
http://test.baidu.com/qss/8760/504886.html
http://test.baidu.com/qss/7db4/504953.html
http://test.baidu.com/qss/f5f6/505043.html
http://test.baidu.com/qss/be74/505135.html
http://test.baidu.com/qss/95ea/505219.html
http://test.baidu.com/qss/05e2/505312.html
http://test.baidu.com/qss/2e14/505390.html
http://test.baidu.com/qss/7092/505464.html
http://test.baidu.com/qss/af43/505559.html
http://test.baidu.com/qss/4095/505639.html
http://test.baidu.com/qss/eaa7/505731.html
http://test.baidu.com/qss/c074/505805.html
http://test.baidu.com/qss/c95d/505885.html
http://test.baidu.com/qss/b93d/505968.html
http://test.baidu.com/qss/e403/506051.html
http://test.baidu.com/qss/d76a/506144.html
http://test.baidu.com/qss/f6e6/506229.html
http://test.baidu.com/qss/0d99/506313.html
http://test.baidu.com/qss/80c1/506418.html
http://test.baidu.com/qss/b0c4/506513.html
http://test.baidu.com/qss/a518/506652.html
http://test.baidu.com/qss/6ec7/506736.html
http://test.baidu.com/qss/6025/506824.html
http://test.baidu.com/qss/55c8/506911.html
http://test.baidu.com/qss/c09a/506979.html
http://test.baidu.com/qss/b0d2/507060.html
http://test.baidu.com/qss/f210/507127.html
http://test.baidu.com/qss/29d5/507200.html
http://test.baidu.com/qss/bcaf/507273.html
http://test.baidu.com/qss/32ad/507355.html
http://test.baidu.com/qss/4586/507439.html
http://test.baidu.com/qss/e26e/507521.html
http://test.baidu.com/qss/8195/507607.html
http://test.baidu.com/qss/0f2f/507680.html
http://test.baidu.com/qss/1e7a/507752.html
http://test.baidu.com/qss/3f51/507833.html
http://test.baidu.com/qss/17be/507901.html
http://test.baidu.com/qss/6a65/507971.html
http://test.baidu.com/qss/d33e/508049.html
http://test.baidu.com/qss/6c21/508125.html
http://test.baidu.com/qss/9da1/508203.html
http://test.baidu.com/qss/0de0/508273.html
http://test.baidu.com/qss/b34d/508346.html
http://test.baidu.com/qss/1cf4/508421.html
http://test.baidu.com/qss/6650/508492.html
http://test.baidu.com/qss/afab/508634.html
http://test.baidu.com/qss/3165/508708.html
http://test.baidu.com/qss/389f/508783.html
http://test.baidu.com/qss/79ca/508844.html
http://test.baidu.com/qss/3684/508919.html
http://test.baidu.com/qss/d49b/508993.html
http://test.baidu.com/qss/3c58/509057.html
http://test.baidu.com/qss/f9fe/509167.html
http://test.baidu.com/qss/ac64/509232.html
http://test.baidu.com/qss/5ba4/509305.html
http://test.baidu.com/qss/f952/509380.html
http://test.baidu.com/qss/4f1f/509458.html
http://test.baidu.com/qss/26ec/509535.html
http://test.baidu.com/qss/1047/509612.html
http://test.baidu.com/qss/67f1/509678.html
http://test.baidu.com/qss/e2d4/509768.html
http://test.baidu.com/qss/ce55/509843.html
http://test.baidu.com/qss/cbf0/509927.html
http://test.baidu.com/qss/233f/510000.html
http://test.baidu.com/qss/eda0/510091.html
http://test.baidu.com/qss/481c/510171.html
http://test.baidu.com/qss/aefc/510263.html
http://test.baidu.com/qss/06c5/510361.html
http://test.baidu.com/qss/b42f/510440.html
http://test.baidu.com/qss/89b2/510513.html
http://test.baidu.com/qss/7b04/510598.html
http://test.baidu.com/qss/ebc2/510680.html
http://test.baidu.com/qss/4f7b/510780.html
http://test.baidu.com/qss/c508/510881.html
http://test.baidu.com/qss/9159/510977.html
http://test.baidu.com/qss/151a/511088.html
http://test.baidu.com/qss/7f2b/511193.html
http://test.baidu.com/qss/9390/511286.html
http://test.baidu.com/qss/042a/511383.html
http://test.baidu.com/qss/d183/511486.html
http://test.baidu.com/qss/39b3/511573.html