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/*

 * @test TestDynamicNumberOfGCThreads

 * @bug 8017462

 * @summary Ensure that UseDynamicNumberOfGCThreads runs

 * @requires vm.gc=="null"

 * @key gc

 * @modules java.base/jdk.internal.misc

 */

public class TestDynamicNumberOfGCThreads {

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

    testDynamicNumberOfGCThreads("UseConcMarkSweepGC");

    testDynamicNumberOfGCThreads("UseG1GC");

    testDynamicNumberOfGCThreads("UseParallelGC");

  }

  private static void verifyDynamicNumberOfGCThreads(OutputAnalyzer output) {

    output.shouldHaveExitValue(0); // test should run succesfully

    output.shouldContain("new_active_workers");

  }

  private static void testDynamicNumberOfGCThreads(String gcFlag) throws Exception {

    // UseDynamicNumberOfGCThreads and TraceDynamicGCThreads enabled

    String[] baseArgs = {"-XX:+" + gcFlag, "-Xmx10M", "-XX:+UseDynamicNumberOfGCThreads", "-Xlog:gc+task=trace", GCTest.class.getName()};

    // Base test with gc and +UseDynamicNumberOfGCThreads:

    ProcessBuilder pb_enabled = ProcessTools.createJavaProcessBuilder(baseArgs);

    verifyDynamicNumberOfGCThreads(new OutputAnalyzer(pb_enabled.start()));

    // Ensure it also works on uniprocessors or if user specifies -XX:ParallelGCThreads=1:

    String[] extraArgs = {"-XX:+UnlockDiagnosticVMOptions", "-XX:+ForceDynamicNumberOfGCThreads", "-XX:ParallelGCThreads=1"};

    String[] finalArgs = new String[baseArgs.length + extraArgs.length];

    System.arraycopy(extraArgs, 0, finalArgs, 0,                extraArgs.length);

    System.arraycopy(baseArgs,  0, finalArgs, extraArgs.length, baseArgs.length);

    pb_enabled = ProcessTools.createJavaProcessBuilder(finalArgs);

    verifyDynamicNumberOfGCThreads(new OutputAnalyzer(pb_enabled.start()));

    // Turn on parallel reference processing

    String[] parRefProcArg = {"-XX:+ParallelRefProcEnabled", "-XX:-ShowMessageBoxOnError"};

    String[] parRefArgs = new String[baseArgs.length + parRefProcArg.length];

    System.arraycopy(parRefProcArg, 0, parRefArgs, 0,                parRefProcArg.length);

    System.arraycopy(baseArgs,  0, parRefArgs, parRefProcArg.length, baseArgs.length);

    pb_enabled = ProcessTools.createJavaProcessBuilder(parRefArgs);

    verifyDynamicNumberOfGCThreads(new OutputAnalyzer(pb_enabled.start()));

  }

  static class GCTest {

    private static byte[] garbage;

    public static void main(String [] args) {

      System.out.println("Creating garbage");

      // create 128MB of garbage. This should result in at least one GC

      for (int i = 0; i < 1024; i++) {

        garbage = new byte[128 * 1024];

      }

      System.out.println("Done");

    }

  }

}