Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved. DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. This code is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License version 2 only, as published by the Free Software Foundation. This code is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License version 2 for more details (a copy is included in the LICENSE file that accompanied this code). You should have received a copy of the GNU General Public License version 2 along with this work; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA or visit www.oracle.com if you need additional information or have any questions. 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.