JVisualVM 简介

jvisualvm是JDK自带的Java性能分析工具,在JDK的bin目录下,文件名就叫jvisualvm.exe。 双击打开即可使用, jvisualvm可以监控本地、远程的java进程,实时查看进程的cpu、堆、线程等参数,对java进程生成dump文件,并对dump文件进行分析。

很多插件 Java VisualVM的最大好处是可通过安装Visual GC插件来分析GC(Gabage Collection)趋势、内存消耗详细状况。

最常用的场景是 从服务器上dump下来文件也可以直接扔给jvisualvm来分析

对于Java8来说,一般堆内存的初始容量为物理内存大小的1/64, 最大内存不超过物理内存的1/4或1G.

initial heap size

Larger of 1/64th of the machine’s physical memory on the machine or some reasonable minimum. Before Java SE 5.0, the default initial heap size was a reasonable minimum, which varies by platform. You can override this default using the -Xms command-line option.

maximum heap size

Smaller of 1/4th of the physical memory or 1GB. Before Java SE 5.0, the default maximum heap size was 64MB. You can override this default using the -Xmx command-line option.

Note: The boundaries and fractions given for the heap size are correct for Java SE 5.0. They are likely to be different in subsequent releases as computers get more powerful.

Post Directory