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Native Memory Tracking

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The Native Memory Tracking (NMT) functionality is available since Azul Platform Prime 16.01.0.0. It includes invocation of Memory-tracking functions to record allocations. It also introduces the use of NativeMemoryTracking pre-header to each allocation (when the feature is enabled).

To enable Native Memory Tracking, use the following command-line options:

 java -XX:+PrintNMTStatistics -XX:NativeMemoryTracking="summary"

The "summary" level of tracking provides basic information about the following native memory allocations:

  • JavaHeap – amount of the native memory allocated for the Java Heap. The committed portion displays the Xmx value.

  • Class – amount of the native memory allocated for the application classes

  • Thread – amount of the native memory allocated for the application threads

  • Code – amount of the native memory allocated for the code is being executed

  • GC – amount of the native memory used by the Garbage Collector

  • Compiler – amount of the native memory allocated for the compiler operations

  • Internal – internal allocations

  • Symbol – amount of the native memory allocated for the table of symbols

  • Native Memory Tracking – amount of the native memory used for the NMT processes

  • Arena Chunk – allocations for the arena-managed chunk

  • Arguments – amount of the native memory allocated for processing arguments

  • Unknown – unspecified allocations

Below is a screen capture of a sample NMT output.

NTM output