ShortLivedSymbolCleanup.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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/*
 * @test
 * @bug 8195100
 * @summary a short lived Symbol should be cleaned up
 * @requires vm.debug
 * @requires vm.flagless
 * @library /test/lib
 * @modules java.base/jdk.internal.misc
 *          java.management
 * @run driver ShortLivedSymbolCleanup
 */

import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;
import java.util.Scanner;

public class ShortLivedSymbolCleanup {

  static int getSymbolTableSize(ProcessBuilder pb) throws Exception {
    int size = 0;

    OutputAnalyzer analyzer = new OutputAnalyzer(pb.start());
    String output = analyzer.getStdout();
    analyzer.shouldHaveExitValue(0);

    // Split string into lines using platform independent end of line marker.
    String[] lines = output.split("\\R");
    for (String line : lines) {
      if (line.contains("Start size")) {
        // ex. "[0.023s][trace][symboltable] Start size: 32768 (15)"
        Scanner scanner = new Scanner(line);
        scanner.next(); // skip "[0.023s][trace][symboltable]"
        scanner.next(); // skip "Start"
        scanner.next(); // skip "size:"
        size = Integer.parseInt(scanner.next()); // process "32768"
        scanner.close();
      }
    }

    return size;
  }

  static void analyzeOutputOn(int size, ProcessBuilder pb) throws Exception {
    OutputAnalyzer analyzer = new OutputAnalyzer(pb.start());
    String output = analyzer.getStdout();
    analyzer.shouldHaveExitValue(0);

    // Split string into lines using platform independent end of line marker.
    String[] lines = output.split("\\R");
    for (String line : lines) {
      if (line.startsWith("  Total removed")) {
        // ex. "Total removed              13309"
        Scanner scanner = new Scanner(line);
        scanner.next(); // skip "Total"
        scanner.next(); // skip "removed"
        int removed = Integer.parseInt(scanner.next()); // process "13309"
        scanner.close();

        if (removed < (size/2)) {
          System.out.println(output);
          // We should have removed at least half of the temporary Symbols
          throw new RuntimeException("Did not clean dead temporary Symbols [removed:"+removed+", size:"+size+"]");
        }
      }
    }
  }

  public static void main(String[] args) throws Exception {
    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder("-Xlog:symboltable=trace",
                                                              "-version");
    int size = getSymbolTableSize(pb);

    pb = ProcessTools.createJavaProcessBuilder("-XX:+PrintSymbolTableSizeHistogram",
                                               LotsOfTempSymbols.class.getName(),
                                               Integer.toString(size));
    analyzeOutputOn(size, pb);
  }

  static class LotsOfTempSymbols {
    public static void main(String [] args) {
      int size = 2*Integer.parseInt(args[0]);
      // Create enough temporary Symbols, that we are
      // guranteed to insert into every bucket twice,
      // and therefore have the table check for dead entries
      for (int i=0; i<size; i++) {
        try {
          Class.forName(String.format("%05d", i), false, null);
        } catch (java.lang.ClassNotFoundException e) {}
      }
    }
  }
}