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/*

 * @test TestParallelGCThreads

 * @key gc

 * @bug 8059527 8081382

 * @summary Tests argument processing for ParallelGCThreads

 * @library /testlibrary

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

 *          java.management

 * @run driver TestParallelGCThreads

 */

import jdk.test.lib.*;

public class TestParallelGCThreads {

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

    testFlags();

    testDefaultValue();

  }

  private static final String flagName = "ParallelGCThreads";

  // uint ParallelGCThreads = 23 {product}

  private static final String printFlagsFinalPattern = " *uint *" + flagName + " *:?= *(\\d+) *\\{product\\} *";

  public static void testDefaultValue()  throws Exception {

    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(

      "-XX:+UnlockExperimentalVMOptions", "-XX:+PrintFlagsFinal", "-version");

    OutputAnalyzer output = new OutputAnalyzer(pb.start());

    String value = output.firstMatch(printFlagsFinalPattern, 1);

    try {

      Asserts.assertNotNull(value, "Couldn't find uint flag " + flagName);

      Long longValue = new Long(value);

      // Sanity check that we got a non-zero value.

      Asserts.assertNotEquals(longValue, "0");

      output.shouldHaveExitValue(0);

    } catch (Exception e) {

      System.err.println(output.getOutput());

      throw e;

    }

  }

  public static void testFlags() throws Exception {

    // For each parallel collector (G1, Parallel, ParNew/CMS)

    for (String gc : new String[] {"G1", "Parallel", "ConcMarkSweep"}) {

      // Make sure the VM does not allow ParallelGCThreads set to 0

      String[] flags = new String[] {"-XX:+Use" + gc + "GC", "-XX:ParallelGCThreads=0", "-XX:+PrintFlagsFinal", "-version"};

      ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(flags);

      OutputAnalyzer output = new OutputAnalyzer(pb.start());

      output.shouldHaveExitValue(1);

      // Do some basic testing to ensure the flag updates the count

      for (long i = 1; i <= 3; i++) {

        flags = new String[] {"-XX:+Use" + gc + "GC", "-XX:ParallelGCThreads=" + i, "-XX:+PrintFlagsFinal", "-version"};

        long count = getParallelGCThreadCount(flags);

        Asserts.assertEQ(count, i, "Specifying ParallelGCThreads=" + i + " for " + gc + "GC does not set the thread count properly!");

      }

    }

    // 4294967295 == (unsigned int) -1

    // So setting ParallelGCThreads=4294967295 should give back 4294967295

    // and setting ParallelGCThreads=4294967296 should give back 0. (SerialGC is ok with ParallelGCThreads=0)

    for (long i = 4294967295L; i <= 4294967296L; i++) {

      String[] flags = new String[] {"-XX:+UseSerialGC", "-XX:ParallelGCThreads=" + i, "-XX:+PrintFlagsFinal", "-version"};

      long count = getParallelGCThreadCount(flags);

      Asserts.assertEQ(count, i % 4294967296L, "Specifying ParallelGCThreads=" + i + " does not set the thread count properly!");

    }

  }

  public static long getParallelGCThreadCount(String flags[]) throws Exception {

    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(flags);

    OutputAnalyzer output = new OutputAnalyzer(pb.start());

    output.shouldHaveExitValue(0);

    String stdout = output.getStdout();

    return FlagsValue.getFlagLongValue("ParallelGCThreads", stdout);

  }

}