java - Java 8中tomcat jvm的输出Java Real memory usage

Question

我想绘制 Java 8 中 tomcat 门户的 java vm 内存使用情况图表。

Java Runtime 值是错误的，它只给出半准确的估计，例如:

Runtime.getRuntime().maxMemory();

我以为我在 stackOverflow 上找到了一个很好的解决方案，但它只适用于 Java 7:

MemoryPoolMXBean testEdenBean = ManagementFactory.getMemoryPoolMXBeans().get(3);
MemoryPoolMXBean testSurvivorBean = ManagementFactory.getMemoryPoolMXBeans().get(4);
MemoryPoolMXBean testTemurBean = ManagementFactory.getMemoryPoolMXBeans().get(5);

max = testEdenBean.getUsage().getMax() 
    + (testSurvivorBean.getUsage().getMax() * 2) 
    + testTemurBean.getUsage().getMax();

Java VisualVM 给了我真正的值(value)，因为如果我用 1024m 启动 tomcat -Xmx，我得到 Max: 1.073.741.824 B，这是正确的。

如何让我的代码输出正确的值？

Answer 1

试试这个:

    MemoryMXBean mbean = ManagementFactory.getMemoryMXBean();
    MemoryUsage heapUsage = mbean.getHeapMemoryUsage();
    System.out.println("Max heap memory is "+heapUsage.getMax()/1024/1024+" MBytes");
    System.out.println("Used heap memory is "+heapUsage.getUsed()/1024/1024+" MBytes");

    MemoryUsage nonHeapUsage= mbean.getNonHeapMemoryUsage();
    System.out.println("Max non-heap memory is "+nonHeapUsage.getMax()/1024/1024+" MBytes");
    System.out.println("Used non-heap memory is "+nonHeapUsage.getUsed()/1024/1024+" MBytes");

如果这就是您要找的，请告诉我。