hotspot/test/serviceability/tmtools/jstat/GcCauseTest01.java

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/*
 * @test
 * @summary Test checks output displayed with jstat -gccause.
 *          Test scenario:
 *          test several times provokes garbage collection in the debuggee application and after each garbage
 *          collection runs jstat. jstat should show that after garbage collection number of GC events and garbage
 *          collection time increase.
 * @modules java.base/jdk.internal.misc
 * @library /test/lib
 * @library ../share
 * @requires vm.opt.ExplicitGCInvokesConcurrent != true
 * @run main/othervm -XX:+UsePerfData -Xmx128M GcCauseTest01
 */
import utils.*;

public class GcCauseTest01 {

    public static void main(String[] args) throws Exception {

        // We will be running "jstat -gc" tool
        JstatGcCauseTool jstatGcTool = new JstatGcCauseTool(ProcessHandle.current().pid());

        // Run once and get the  results asserting that they are reasonable
        JstatGcCauseResults measurement1 = jstatGcTool.measure();
        measurement1.assertConsistency();

        GcProvoker gcProvoker = new GcProvoker();

        // Provoke GC then run the tool again and get the results  asserting that they are reasonable
        gcProvoker.provokeGc();
        JstatGcCauseResults measurement2 = jstatGcTool.measure();
        measurement2.assertConsistency();

        // Assert the increase in GC events and time between the measurements
        JstatResults.assertGCEventsIncreased(measurement1, measurement2);
        JstatResults.assertGCTimeIncreased(measurement1, measurement2);

        // Provoke GC 3rd time then run the tool 3rd time twice and get the results
        // asserting that they are reasonable
        gcProvoker.provokeGc();
        JstatGcCauseResults measurement3 = jstatGcTool.measure();
        measurement3.assertConsistency();

        // Assert the increase in GC events and time between the measurements
        JstatResults.assertGCEventsIncreased(measurement2, measurement3);
        JstatResults.assertGCTimeIncreased(measurement2, measurement3);
    }
}