Metaspace中的PeakUsageMax始终为负数

Question

我正在捕获jvm的内存数据，但是当我获取内存的数据（即元空间）时，我得到的是负值（

  

“ peakUsageMax”：-1，                 “ usageMax”：-1

）

我正在使用

  

ManagementFactory.getMemoryPoolMXBeans（）

获取数据。我不知道为什么我要得到元数据的负面数据。难道我做错了什么？ 我的数据是：

"Memory Data":[  
        {  
            "peakUsageMax":251658240,
            "usageMax":251658240,
            "peakUsageUsed":3136768,
            "name":"Code Cache",
            "peakUsageCommitted":3211264,
            "usageUsed":3136768,
            "type":"Non-heap memory",
            "usageCommitted":3211264
        },
        {  
            "peakUsageMax":-1,
            "usageMax":-1,
            "peakUsageUsed":8491352,
            "name":"Metaspace",
            "peakUsageCommitted":8912896,
            "usageUsed":8491352,
            "type":"Non-heap memory",
            "usageCommitted":8912896
        },
        {  
            "peakUsageMax":1073741824,
            "usageMax":1073741824,
            "peakUsageUsed":943688,
            "name":"Compressed Class Space",
            "peakUsageCommitted":1048576,
            "usageUsed":943688,
            "type":"Non-heap memory",
            "usageCommitted":1048576
        },
        {  
            "peakUsageMax":680001536,
            "usageMax":680001536,
            "peakUsageUsed":14971840,
            "name":"PS Eden Space",
            "peakUsageCommitted":32505856,
            "usageUsed":2600792,
            "type":"Heap memory",
            "usageCommitted":32505856
        },
        {  
            "peakUsageMax":5242880,
            "usageMax":5242880,
            "peakUsageUsed":2502552,
            "name":"PS Survivor Space",
            "peakUsageCommitted":5242880,
            "usageUsed":0,
            "type":"Heap memory",
            "usageCommitted":5242880
        },
        {  
            "peakUsageMax":1381498880,
            "usageMax":1381498880,
            "peakUsageUsed":2332616,
            "name":"PS Old Gen",
            "peakUsageCommitted":87031808,
            "usageUsed":1608248,
            "type":"Heap memory",
            "usageCommitted":87031808
        }
    ]