JVM Management Runtime ThreadGroup

1.代碼調用內存情況 Runtime runtime = Runtime.getRuntime();

 1)JVM可用最大內存：long max = runtime.maxMemory() (byte)

 2)JVM佔用總內存：long total = runtime.totalMemory() (byte) 

  3)JVM空閒內存 ： long free = runtime.freeMemory() (byte) 

4)JVM可用處理器： int availableProcessors = runtime.availableProcessors();

2.線程組使用情況：

ThreadGroup group = Thread.currentThread().getThreadGroup();

ThreadGroup topGroup = group;// 遍歷線程組樹，獲取根線程組

while (group != null) { topGroup = group; group = group.getParent();}

  1)當前的活動線程總數 : topGroup.activeCount(); 

2)線程組總數 : topGroup.activeGroupCount();

3.ManagemntFactory : GC、內存、編譯等管理情況

  1)獲取GC信息

    long gcCounts = 0;

   long gcTimes = 0;

   for (final GarbageCollectorMXBean gcCollector : ManagementFactory.getGarbageCollectorMXBeans()) {

gcCounts += gcCollector.getCollectionCount();

        gcTimes +=  gcCollector.getCollectionTime();

   }

 2).獲取Memory信息

      MemoryMXBean memoryMXBean = ManagementFactory.getMemoryMXBean();

long getFinallzationCount = memoryMxBean.getObjectPendingFinalizationCount();

String heapMemoryUsage  = memoryMxBean.getHeapMemoryUsage().toString();

String nonHeapMemoryUsage = memoryMXBean.getNonHeapMemoryUsage().toString();