使用java代码获取JVM信息

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　　最近在环境中定位服务问题，由于服务使用的docker部署的，且使用的docker镜像，在启动之后，容器内没有jdk相关的工具【jstat、jmap等等】；于是采用 在项目中使用java类获取jvm相关信息，以下是测试的示例：

import java.lang.management.ManagementFactory;
import java.lang.management.MemoryMXBean;
import java.lang.management.MemoryUsage;
import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.MemoryPoolMXBean;
import java.lang.management.ThreadMXBean;  

import java.util.List;  

public class GCInfoDemo {
    public static void main(String[] args) {
        // 获取内存管理 bean
        MemoryMXBean memoryMXBean = ManagementFactory.getMemoryMXBean();
        MemoryUsage heapMemoryUsage = memoryMXBean.getHeapMemoryUsage();
        MemoryUsage nonHeapMemoryUsage = memoryMXBean.getNonHeapMemoryUsage();  

        // 打印内存信息
        System.out.println("Heap Memory Usage:");
        System.out.println("  Init: " + heapMemoryUsage.getInit() / (1024 * 1024) + " MB");
        System.out.println("  Used: " + heapMemoryUsage.getUsed() / (1024 * 1024) + " MB");
        System.out.println("  Committed: " + heapMemoryUsage.getCommitted() / (1024 * 1024) + " MB");
        System.out.println("  Max: " + heapMemoryUsage.getMax() / (1024 * 1024) + " MB");  

        System.out.println("\nNon-Heap Memory Usage:");
        System.out.println("  Init: " + nonHeapMemoryUsage.getInit() / (1024 * 1024) + " MB");
        System.out.println("  Used: " + nonHeapMemoryUsage.getUsed() / (1024 * 1024) + " MB");
        System.out.println("  Committed: " + nonHeapMemoryUsage.getCommitted() / (1024 * 1024) + " MB");
        System.out.println("  Max: " + nonHeapMemoryUsage.getMax() / (1024 * 1024) + " MB");  

        // 获取垃圾回收回收器 bean 的列表
        List<GarbageCollectorMXBean> gcBeans = ManagementFactory.getGarbageCollectorMXBeans();
        System.out.println("\nGarbage Collectors:");
        for (GarbageCollectorMXBean gcBean : gcBeans) {
            System.out.println("  Name: " + gcBean.getName());
            System.out.println("  Number of collections: " + gcBean.getCollectionCount());
            System.out.println("  Total time spent in collections: " + gcBean.getCollectionTime() + " ms");
        }  

        // 打印内存池信息
        System.out.println("\nMemory Pools:");
        for (MemoryPoolMXBean memoryPool : ManagementFactory.getMemoryPoolMXBeans()) {
            System.out.println("  Name: " + memoryPool.getName());
            System.out.println("  Usage: " + memoryPool.getUsage());
        }  

        // 获取线程管理 bean
        ThreadMXBean threadMXBean = ManagementFactory.getThreadMXBean();  

        // 获取所有线程 ID
        long[] threadIds = threadMXBean.getAllThreadIds();
        System.out.println("\nThreads Information:");
        for (long threadId : threadIds) {
            System.out.println("  Thread ID: " + threadId);
            System.out.println("  Thread Name: " + threadMXBean.getThreadInfo(threadId).getThreadName());
            System.out.println("  Thread State: " + threadMXBean.getThreadInfo(threadId).getThreadState());
        }  

        // 检查死锁线程
        long[] deadlockedThreads = threadMXBean.findDeadlockedThreads();
        if (deadlockedThreads != null) {
            System.out.println("\nDeadlocked Threads:");
            for (long deadlockedThreadId : deadlockedThreads) {
                System.out.println("  Deadlocked Thread ID: " + deadlockedThreadId);
                System.out.println("  Thread Name: " + threadMXBean.getThreadInfo(deadlockedThreadId).getThreadName());
            }
        } else {
            System.out.println("\nNo deadlocked threads found.");
        }
    }
}  

1. 获取GC信息

   • 通过ManagementFactory.getGarbageCollectorMXBeans()获取所有垃圾回收器的监控Bean。

   • 每个GarbageCollectorMXBean提供：

     • getName()：GC算法名称（如G1 Young Generation）

     • getCollectionCount()：回收次数

     • getCollectionTime()：累计耗时（毫秒）

　　  2.打印当前线程信息：

1. • 使用 ThreadMXBean 获取当前线程的所有 ID，并通过 getThreadInfo 方法获取每个线程的信息，包括线程名字和状态。

　　  3.检查死锁线程：

1. • 使用 findDeadlockedThreads 方法检查 JVM 中的死锁情况。如果有死锁线程，则输出这些线程的 ID 和名称。如果没有，则输出相应的消息。

Heap Memory Usage:
  Init: 508 MB
  Used: 10 MB
  Committed: 487 MB
  Max: 7205 MB

Non-Heap Memory Usage:
  Init: 2 MB
  Used: 4 MB
  Committed: 7 MB
  Max: 0 MB

Garbage Collectors:
  Name: PS Scavenge
  Number of collections: 0
  Total time spent in collections: 0 ms
  Name: PS MarkSweep
  Number of collections: 0
  Total time spent in collections: 0 ms

Memory Pools:
  Name: Code Cache
  Usage: init = 2555904(2496K) used = 1235968(1207K) committed = 2555904(2496K) max = 251658240(245760K)
  Name: Metaspace
  Usage: init = 0(0K) used = 3597432(3513K) committed = 4980736(4864K) max = -1(-1K)
  Name: Compressed Class Space
  Usage: init = 0(0K) used = 392584(383K) committed = 524288(512K) max = 1073741824(1048576K)
  Name: PS Eden Space
  Usage: init = 133169152(130048K) used = 10914704(10658K) committed = 133169152(130048K) max = 2789212160(2723840K)
  Name: PS Survivor Space
  Usage: init = 22020096(21504K) used = 0(0K) committed = 22020096(21504K) max = 22020096(21504K)
  Name: PS Old Gen
  Usage: init = 355467264(347136K) used = 0(0K) committed = 355467264(347136K) max = 5666504704(5533696K)

Threads Information:
  Thread ID: 6
  Thread Name: Monitor Ctrl-Break
  Thread State: RUNNABLE
  Thread ID: 5
  Thread Name: Attach Listener
  Thread State: RUNNABLE
  Thread ID: 4
  Thread Name: Signal Dispatcher
  Thread State: RUNNABLE
  Thread ID: 3
  Thread Name: Finalizer
  Thread State: WAITING
  Thread ID: 2
  Thread Name: Reference Handler
  Thread State: WAITING
  Thread ID: 1
  Thread Name: main
  Thread State: RUNNABLE

No deadlocked threads found.

Process finished with exit code 0