小知识点 之 JVM -XX:SurvivorRatio

JVM参数之-XX:SurvivorRatio

最近面试过程中遇到一些问JVM参数的，本着没用过去学习的办法看了些博客写得不准确，参考oracle的文档记录一下，争取每天记录一点知识点

• -XX:SurvivorRatio=6 ，设置的是Eden区与每一个Survivor区的比值，可以反推出占新生代的比值，Eden为6, 两个Survivor为2, Eden占新生代的3/4, 每个Survivor占1/8，两个占1/4

  原文：

  Survivor Ratio Sizing

  The SurvivorRatio parameter controls the size of the two survivor spaces. For example, -XX:SurvivorRatio=6 sets the ratio between each survivor space and eden to be 1:6, each survivor space will be one eighth of the young generation. The default for Solaris is 32. If survivor spaces are too small, copying collection overflows directly into the old generation. If survivor spaces are too large, they will be empty. At each GC, the JVM determines the number of times an object can be copied before it is tenured, called the tenure threshold. This threshold is chosen to keep the survivor space half full.

  Use the option -XX:+PrintTenuringDistribution to show the threshold and ages of the objects in the new generation. It is useful for observing the lifetime distribution of an application.

  出处：https://docs.oracle.com/cd/E19159-01/819-3681/abeil/index.html