test/hotspot/jtreg/runtime/LoadClass/TestResize.java

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/*
 * @test
 * @bug 8184765
 * @summary make sure the SystemDictionary gets resized when load factor is too high
 * @requires vm.debug
 * @requires vm.flagless
 * @library /test/lib
 * @modules java.base/jdk.internal.misc
 *          java.management
 * @compile TriggerResize.java
 * @run driver TestResize
 */

import jdk.test.lib.Platform;
import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.lang.Process;
import java.lang.ProcessBuilder;
import java.util.Scanner;

public class TestResize {

  static double MAX_LOAD_FACTOR = 5.0; // see _resize_load_trigger in dictionary.cpp
  static int CLASSES_TO_LOAD = 30000;

  static int getInt(String string) {
    int start = 0;
    for (int i = 0; i < string.length(); i++) {
      if (!Character.isDigit(string.charAt(i))) {
        start++;
      } else {
        break;
      }
    }
    int end = start;
    for (int i = end; i < string.length(); i++) {
      if (Character.isDigit(string.charAt(i))) {
        end++;
      } else {
        break;
      }
    }
    return Integer.parseInt(string.substring(start, end));
  }

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

    boolean resized = false;
    boolean checked_load_factor = false;

    // Split string into lines using platform independent end of line marker.
    String[] lines = output.split("\\R");
    for (String line : lines) {
      if (!resized) {
        // ex. [0.563s][info][safepoint,cleanup] resizing system dictionaries, 0.0000002 secs
        if (line.contains("resizing system dictionaries")) {
          resized = true;
        }
      } else if (resized) {
        int index = -1;
        if ((index = line.indexOf("Java dictionary (")) != -1) {
          // ex. Java dictionary (table_size=10103, classes=5002)
          String dict = line.substring(index);
          Scanner scanner = new Scanner(dict);
          scanner.next(); // skip "Java"
          scanner.next(); // skip "dictionary"
          int table_size = getInt(scanner.next()); // process "(table_size=40423"
          int classes = getInt(scanner.next()); // process ", classes=50002"
          scanner.close();

          checked_load_factor = classes >= CLASSES_TO_LOAD;

          double loadFactor = (double)classes / (double)table_size;
          if (loadFactor > MAX_LOAD_FACTOR) {

            // We've hit an error, so print all of the output.
            System.out.println(output);

            throw new RuntimeException("Load factor too high, expected MAX " + MAX_LOAD_FACTOR +
                  ", got " + loadFactor + " [table size " + table_size + ", number of clases " + classes + "]");
          } else {
            checked_load_factor = true;
            System.out.println("PASS table_size: " + table_size + ", classes: " + classes +
                ", load factor: " + loadFactor + " <= " + MAX_LOAD_FACTOR);
                // There are more than one system dictionary to check, so keep looking...
          }
        }
      }
    }

    if (!resized) {
      System.out.println("PASS trivially. No resizing occurred, so did not check the load.");
    } else {
      // Make sure the load factor was checked
      if (!checked_load_factor) {
        throw new RuntimeException("Test didn't check load factor");
      }
    }
  }

  public static void main(String[] args) throws Exception {
    // -XX:+PrintClassLoaderDataGraphAtExit will print the summary of the dictionaries,
    // that will allow us to calculate the table's load factor.
    // -Xlog:safepoint+cleanup will print out cleanup details at safepoint
    // that will allow us to detect if the system dictionary resized.
    ProcessBuilder pb = ProcessTools.createLimitedTestJavaProcessBuilder("-XX:+PrintClassLoaderDataGraphAtExit",
                                                                         "-Xlog:safepoint+cleanup,class+loader+data",
                                                                         "TriggerResize",
                                                                         String.valueOf(CLASSES_TO_LOAD));
    analyzeOutputOn(pb);
  }
}