test/gc/ergonomics/TestDynamicNumberOfGCThreads.java

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/*
 * @test TestDynamicNumberOfGCThreads
 * @bug 8017462
 * @summary Ensure that UseDynamicNumberOfGCThreads runs
 * @requires vm.gc=="null"
 * @key gc
 * @library /testlibrary
 */

import com.oracle.java.testlibrary.ProcessTools;
import com.oracle.java.testlibrary.OutputAnalyzer;

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:+PrintGCDetails",  "-XX:+UseDynamicNumberOfGCThreads", "-XX:+TraceDynamicGCThreads", 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()));
  }

  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");
    }
  }
}