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  22 
  23 
  24 metaspace/gc tests - are the test for the Metaspace GC tuning, which is described in the
  25 Java SE 8 HotSpot[tm] Virtual Machine Garbage  Collection Tuning
  26 
  27 Tests load classes and monitor the used/committed amounts of metaspace.
  28 There are three types of tests all extending base class - MetaspaceBaseGC
  29 
  30 MemoryUsageTest -
  31   trivial test to check memory dynamic (loading classes should lead to growth
  32   of used memory, gc to reduce)
  33 
  34 FirstGCTest -
  35   loads classes until the GC has happened and check the GC has happened at the
  36   right moment (as stated in the Spec)
  37 
  38 HighWaterMarkTest
  39   The test loads classes until the committed metaspace achieves the certain
  40   level between MetaspaceSize and MaxMetaspaceSize.
  41   Then it counts how many times GC has been induced.
  42   Test verifies that MinMetaspaceFreeRatio/MaxMetaspaceFreeRatio settings
  43   affect the frequency of GC. (High-water mark)
  44 
  45 Note: GC could be caused not by Metaspace. When GC happens, the tests check
  46 gc.log file to find the reason of GC. Tests will pass if there is no guarantee
  47 that GC was induced by metaspace.