jdk/test/hotspot/jtreg/gc/arguments/TestParallelGCThreads.java

/*
 * Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */

package gc.arguments;

/*
 * @test id=DefaultValue
 * @bug 8059527 8081382
 * @summary Tests default value of ParallelGCThreads
 * @library /test/lib
 * @library /
 * @requires vm.gc.Z | vm.gc.Parallel | vm.gc.G1
 * @run driver gc.arguments.TestParallelGCThreads DefaultValue
 */

/*
 * @test id=Z
 * @bug 8059527 8081382
 * @summary Tests argument processing for ParallelGCThreads with ZGC
 * @library /test/lib
 * @library /
 * @requires vm.gc.Z
 * @run driver gc.arguments.TestParallelGCThreads Z
 */

/*
 * @test id=Parallel
 * @bug 8059527 8081382
 * @summary Tests argument processing for ParallelGCThreads with Parallel GC
 * @library /test/lib
 * @library /
 * @requires vm.gc.Parallel
 * @run driver gc.arguments.TestParallelGCThreads Parallel
 */

/*
 * @test id=G1
 * @bug 8059527 8081382
 * @summary Tests argument processing for ParallelGCThreads with G1 GC
 * @library /test/lib
 * @library /
 * @requires vm.gc.G1
 * @run driver gc.arguments.TestParallelGCThreads G1
 */

/*
 * @test id=MaxValue
 * @bug 8059527 8081382
 * @summary Tests max value for ParallelGCThreads
 * @library /test/lib
 * @library /
 * @requires vm.gc.Serial
 * @run driver gc.arguments.TestParallelGCThreads MaxValue
 */

import jdk.test.lib.Asserts;
import jdk.test.lib.process.OutputAnalyzer;

public class TestParallelGCThreads {

  public static void main(String args[]) throws Exception {
    if (args.length == 0) {
      throw new IllegalArgumentException("Test type must be specified as argument");
    }

    String testType = args[0];

    switch (testType) {
      case "DefaultValue":
        testDefaultValue();
        break;
      case "Z":
        testFlags("-XX:+UseZGC");
        break;
      case "Parallel":
        testFlags("-XX:+UseParallelGC");
        break;
      case "G1":
        testFlags("-XX:+UseG1GC");
        break;
      case "MaxValue":
        testMaxValue();
        break;
      default:
        throw new IllegalArgumentException("Unknown test type \"" + testType + "\"");
    }
  }

  private static final String flagName = "ParallelGCThreads";

  // uint ParallelGCThreads = 23 {product}
  private static final String printFlagsFinalPattern = " *uint *" + flagName + " *:?= *(\\d+) *\\{product\\} *";

  private static void testDefaultValue()  throws Exception {
    OutputAnalyzer output = GCArguments.executeTestJava(
      "-XX:+UnlockExperimentalVMOptions", "-XX:+PrintFlagsFinal", "-version");

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

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

      Long longValue = Long.valueOf(value);

      // Sanity check that we got a non-zero value.
      Asserts.assertNotEquals(longValue, 0L);

      output.shouldHaveExitValue(0);
    } catch (Exception e) {
      System.err.println(output.getOutput());
      throw e;
    }
  }

  private static void testFlags(String gcFlag) throws Exception {

    // Make sure the VM does not allow ParallelGCThreads set to 0
    OutputAnalyzer output = GCArguments.executeTestJava(
        gcFlag,
        "-XX:ParallelGCThreads=0",
        "-XX:+PrintFlagsFinal",
        "-version");
    output.shouldHaveExitValue(1);

    // Do some basic testing to ensure the flag updates the count
    for (long i = 1; i <= 3; i++) {
      long count = getParallelGCThreadCount(
          gcFlag,
          "-XX:ParallelGCThreads=" + i,
          "-XX:+PrintFlagsFinal",
          "-version");
      Asserts.assertEQ(count, i, "Specifying ParallelGCThreads=" + i + " for \"" + gcFlag + "\" does not set the thread count properly!");
    }
  }

  private static void testMaxValue() throws Exception {
    // Test the max value for ParallelGCThreads
    // So setting ParallelGCThreads=2147483647 should give back 2147483647
    long count = getParallelGCThreadCount(
        "-XX:+UseSerialGC",
        "-XX:ParallelGCThreads=2147483647",
        "-XX:+PrintFlagsFinal",
        "-version");
    Asserts.assertEQ(count, 2147483647L, "Specifying ParallelGCThreads=2147483647 does not set the thread count properly!");
  }

  public static long getParallelGCThreadCount(String... flags) throws Exception {
    OutputAnalyzer output = GCArguments.executeTestJava(flags);
    output.shouldHaveExitValue(0);
    String stdout = output.getStdout();
    return FlagsValue.getFlagLongValue("ParallelGCThreads", stdout);
  }
}