Monitoring - Resources

The “Resources” tab displays the status of the resources of the Virtual DataPort server: CPU, memory and garbage collector.

Resources tab of a monitored server

Resources tab of a monitored server

Before explaining all the measures in the tab, you need to understand the following concepts:

  • Heap Memory: Runtime data area maintained by the JVM where the memory is allocated dynamically.
  • Garbage Collector: Automatic memory management system that reclaims unused memory from the heap region.
  • Memory Pool: Memory area in which the JVM divides the memory according to the times their content has survived a garbage collection. The region that has survived several garbage collections is called “Old Generation Memory Pool”; otherwise, it is called “Young Generation Memory Pool” [1]. Each pool has its own garbage collection algorithm.

The measures displayed in the “Resources” tab are:

  • CPU Usage: Percentage of usage of the CPU.
  • Garbage Collection Usage: Percentage of usage of the garbage collector.
  • Used Heap: Amount of heap memory (in MB) occupied with actual data.
  • Committed Heap: Amount of heap memory (in MB) reserved by the JVM.
  • Max Heap: Maximum amount of heap memory (in MB) that can be used.
  • Used Old Gen: Amount of memory (in MB) in the old generation pool occupied with actual data.
  • Max Old Gen: Maximum amount of memory (in MB) in the old generation pool that can be used.
  • Used Young Gen: Amount of memory (in MB) in the young generation pool occupied with actual data.
  • Max Young Gen: Maximum amount of memory (in MB) in the young generation pool that can be used.
  • Old Gen Collection Time: Accumulated time (in milliseconds) the garbage collection has elapsed in the old generation pool.
  • Young Gen Collection Time: Accumulated time (in milliseconds) the garbage collection has elapsed in the young generation pool.
  • Old Gen Collection Usage: Percentage of usage of the garbage collection in the old generation pool.
  • Young Gen Collection Usage: Percentage of usage of the garbage collection in the young generation pool.
  • Old Gen Collection Count: Number of times the garbage collection has occurred in the old generation pool.
  • Young Gen Collection Count: Number of times the garbage collection has occurred in the young generation pool.

Footnotes

[1]The JVM can manage several young generation pools, like “Eden space” and “Survivor space”. The Diagnostic & Monitoring Tool considers the sum of all of them.