TestDisableExplicitGC.java

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package gc;

/*
 * @test TestDisableExplicitGC
 * @requires vm.opt.DisableExplicitGC == null
 * @summary Verify GC behavior with DisableExplicitGC flag.
 * @library /test/lib
 * @modules java.base/jdk.internal.misc
 * @modules jdk.management/com.sun.management.internal
 * @run main/othervm                             -Xlog:gc=debug gc.TestDisableExplicitGC
 * @run main/othervm/fail -XX:+DisableExplicitGC -Xlog:gc=debug gc.TestDisableExplicitGC
 * @run main/othervm      -XX:-DisableExplicitGC -Xlog:gc=debug gc.TestDisableExplicitGC
 */
import java.lang.management.GarbageCollectorMXBean;
import java.util.List;
import static jdk.test.lib.Asserts.*;

public class TestDisableExplicitGC {

    public static void main(String[] args) throws InterruptedException {
        List<GarbageCollectorMXBean> list = java.lang.management.ManagementFactory.getGarbageCollectorMXBeans();
        long collectionCountBefore = getCollectionCount(list);
        System.gc();
        long collectionCountAfter = getCollectionCount(list);
        assertLT(collectionCountBefore, collectionCountAfter);
    }

    private static long getCollectionCount(List<GarbageCollectorMXBean> list) {
        int collectionCount = 0;
        for (GarbageCollectorMXBean gcMXBean : list) {
            collectionCount += gcMXBean.getCollectionCount();
        }
        return collectionCount;
    }
}