jdk-24/test/hotspot/jtreg/runtime/ClassUnload/UnloadTestWithVerifyDuringGC.java

85 lines
3.7 KiB
Java

/*
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* 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
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*
* 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.
*
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/*
* @test Class unloading test with concurrent mark
* @summary Make sure that verification during gc does not prevent class unloading
* @bug 8280454
* @requires vm.gc.G1
* @requires vm.opt.final.ClassUnloading
* @requires vm.opt.final.ClassUnloadingWithConcurrentMark
* @modules java.base/jdk.internal.misc
* @library /test/lib
* @library classes
* @build jdk.test.whitebox.WhiteBox test.Empty
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UseG1GC -XX:+UnlockDiagnosticVMOptions -XX:+VerifyDuringGC -XX:+AlwaysTenure -XX:+WhiteBoxAPI -Xlog:gc,class+unload=debug UnloadTestWithVerifyDuringGC
*/
import jdk.test.whitebox.WhiteBox;
import jdk.test.lib.classloader.ClassUnloadCommon;
/**
* Test that verifies that classes are unloaded using concurrent mark with G1 when they are no
* longer reachable even when -XX:+VerifyDuringGC is enabled
*
* The test creates a class loader, uses the loader to load a class and creates an instance
* of that class. The it nulls out all the references to the instance, class and class loader
* and tries to trigger class unloading using a concurrent mark. Then it verifies that the class
* is no longer loaded by the VM.
*/
public class UnloadTestWithVerifyDuringGC {
private static final WhiteBox wb = WhiteBox.getWhiteBox();
private static void triggerUnloadingWithConcurrentMark() throws Exception {
// Try to unload classes using concurrent mark.
wb.g1RunConcurrentGC();
}
private static String className = "test.Empty";
public static void main(String... args) throws Exception {
ClassUnloadCommon.failIf(wb.isClassAlive(className), "is not expected to be alive yet");
ClassLoader cl = ClassUnloadCommon.newClassLoader();
Class<?> c = cl.loadClass(className);
Object o = c.newInstance();
ClassUnloadCommon.failIf(!wb.isClassAlive(className), "should be live here");
String loaderName = cl.getName();
int loadedRefcount = wb.getSymbolRefcount(loaderName);
System.out.println("Refcount of symbol " + loaderName + " is " + loadedRefcount);
// Move everything into the old gen so that concurrent mark can unload.
wb.youngGC();
cl = null; c = null; o = null;
triggerUnloadingWithConcurrentMark();
ClassUnloadCommon.failIf(wb.isClassAlive(className), "should have been unloaded");
int unloadedRefcount = wb.getSymbolRefcount(loaderName);
System.out.println("Refcount of symbol " + loaderName + " is " + unloadedRefcount);
ClassUnloadCommon.failIf(unloadedRefcount != (loadedRefcount - 1), "Refcount must be decremented");
}
}