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