--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/gc/g1/TestStringDeduplicationTools.java Tue Mar 18 19:07:22 2014 +0100
@@ -0,0 +1,512 @@
+/*
+ * Copyright (c) 2014, 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * Common code for string deduplication tests
+ */
+
+import java.lang.management.*;
+import java.lang.reflect.*;
+import java.security.*;
+import java.util.*;
+import com.oracle.java.testlibrary.*;
+import sun.misc.*;
+
+class TestStringDeduplicationTools {
+ private static final String YoungGC = "YoungGC";
+ private static final String FullGC = "FullGC";
+
+ private static final int Xmn = 50; // MB
+ private static final int Xms = 100; // MB
+ private static final int Xmx = 100; // MB
+ private static final int MB = 1024 * 1024;
+ private static final int StringLength = 50;
+
+ private static Field valueField;
+ private static Unsafe unsafe;
+ private static byte[] dummy;
+
+ static {
+ try {
+ Field field = Unsafe.class.getDeclaredField("theUnsafe");
+ field.setAccessible(true);
+ unsafe = (Unsafe)field.get(null);
+
+ valueField = String.class.getDeclaredField("value");
+ valueField.setAccessible(true);
+ } catch (Exception e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static Object getValue(String string) {
+ try {
+ return valueField.get(string);
+ } catch (Exception e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static void doFullGc(int numberOfTimes) {
+ for (int i = 0; i < numberOfTimes; i++) {
+ System.out.println("Begin: Full GC " + (i + 1) + "/" + numberOfTimes);
+ System.gc();
+ System.out.println("End: Full GC " + (i + 1) + "/" + numberOfTimes);
+ }
+ }
+
+ private static void doYoungGc(int numberOfTimes) {
+ // Provoke at least numberOfTimes young GCs
+ final int objectSize = 128;
+ final int maxObjectInYoung = (Xmn * MB) / objectSize;
+ for (int i = 0; i < numberOfTimes; i++) {
+ System.out.println("Begin: Young GC " + (i + 1) + "/" + numberOfTimes);
+ for (int j = 0; j < maxObjectInYoung + 1; j++) {
+ dummy = new byte[objectSize];
+ }
+ System.out.println("End: Young GC " + (i + 1) + "/" + numberOfTimes);
+ }
+ }
+
+ private static void forceDeduplication(int ageThreshold, String gcType) {
+ // Force deduplication to happen by either causing a FullGC or a YoungGC.
+ // We do several collections to also provoke a situation where the the
+ // deduplication thread needs to yield while processing the queue. This
+ // also tests that the references in the deduplication queue are adjusted
+ // accordingly.
+ if (gcType.equals(FullGC)) {
+ doFullGc(3);
+ } else {
+ doYoungGc(ageThreshold + 3);
+ }
+ }
+
+ private static String generateString(int id) {
+ StringBuilder builder = new StringBuilder(StringLength);
+
+ builder.append("DeduplicationTestString:" + id + ":");
+
+ while (builder.length() < StringLength) {
+ builder.append('X');
+ }
+
+ return builder.toString();
+ }
+
+ private static ArrayList<String> createStrings(int total, int unique) {
+ System.out.println("Creating strings: total=" + total + ", unique=" + unique);
+ if (total % unique != 0) {
+ throw new RuntimeException("Total must be divisible by unique");
+ }
+
+ ArrayList<String> list = new ArrayList<String>(total);
+ for (int j = 0; j < total / unique; j++) {
+ for (int i = 0; i < unique; i++) {
+ list.add(generateString(i));
+ }
+ }
+
+ return list;
+ }
+
+ private static void verifyStrings(ArrayList<String> list, int uniqueExpected) {
+ for (;;) {
+ // Check number of deduplicated strings
+ ArrayList<Object> unique = new ArrayList<Object>(uniqueExpected);
+ for (String string: list) {
+ Object value = getValue(string);
+ boolean uniqueValue = true;
+ for (Object obj: unique) {
+ if (obj == value) {
+ uniqueValue = false;
+ break;
+ }
+ }
+
+ if (uniqueValue) {
+ unique.add(value);
+ }
+ }
+
+ System.out.println("Verifying strings: total=" + list.size() +
+ ", uniqueFound=" + unique.size() +
+ ", uniqueExpected=" + uniqueExpected);
+
+ if (unique.size() == uniqueExpected) {
+ System.out.println("Deduplication completed");
+ break;
+ } else {
+ System.out.println("Deduplication not completed, waiting...");
+
+ // Give the deduplication thread time to complete
+ try {
+ Thread.sleep(1000);
+ } catch (Exception e) {
+ throw new RuntimeException(e);
+ }
+ }
+ }
+ }
+
+ private static OutputAnalyzer runTest(String... extraArgs) throws Exception {
+ String[] defaultArgs = new String[] {
+ "-Xmn" + Xmn + "m",
+ "-Xms" + Xms + "m",
+ "-Xmx" + Xmx + "m",
+ "-XX:+UseG1GC",
+ "-XX:+UnlockDiagnosticVMOptions",
+ "-XX:+VerifyAfterGC" // Always verify after GC
+ };
+
+ ArrayList<String> args = new ArrayList<String>();
+ args.addAll(Arrays.asList(defaultArgs));
+ args.addAll(Arrays.asList(extraArgs));
+
+ ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(args.toArray(new String[args.size()]));
+ OutputAnalyzer output = new OutputAnalyzer(pb.start());
+ System.err.println(output.getStderr());
+ System.out.println(output.getStdout());
+ return output;
+ }
+
+ private static class DeduplicationTest {
+ public static void main(String[] args) {
+ System.out.println("Begin: DeduplicationTest");
+
+ final int numberOfStrings = Integer.parseUnsignedInt(args[0]);
+ final int numberOfUniqueStrings = Integer.parseUnsignedInt(args[1]);
+ final int ageThreshold = Integer.parseUnsignedInt(args[2]);
+ final String gcType = args[3];
+
+ ArrayList<String> list = createStrings(numberOfStrings, numberOfUniqueStrings);
+ forceDeduplication(ageThreshold, gcType);
+ verifyStrings(list, numberOfUniqueStrings);
+
+ System.out.println("End: DeduplicationTest");
+ }
+
+ public static OutputAnalyzer run(int numberOfStrings, int ageThreshold, String gcType, String... extraArgs) throws Exception {
+ String[] defaultArgs = new String[] {
+ "-XX:+UseStringDeduplication",
+ "-XX:StringDeduplicationAgeThreshold=" + ageThreshold,
+ DeduplicationTest.class.getName(),
+ "" + numberOfStrings,
+ "" + numberOfStrings / 2,
+ "" + ageThreshold,
+ gcType
+ };
+
+ ArrayList<String> args = new ArrayList<String>();
+ args.addAll(Arrays.asList(extraArgs));
+ args.addAll(Arrays.asList(defaultArgs));
+
+ return runTest(args.toArray(new String[args.size()]));
+ }
+ }
+
+ private static class InternedTest {
+ public static void main(String[] args) {
+ // This test verifies that interned strings are always
+ // deduplicated when being interned, and never after
+ // being interned.
+
+ System.out.println("Begin: InternedTest");
+
+ final int ageThreshold = Integer.parseUnsignedInt(args[0]);
+ final String baseString = "DeduplicationTestString:" + InternedTest.class.getName();
+
+ // Create duplicate of baseString
+ StringBuilder sb1 = new StringBuilder(baseString);
+ String dupString1 = sb1.toString();
+ if (getValue(dupString1) == getValue(baseString)) {
+ throw new RuntimeException("Values should not match");
+ }
+
+ // Force baseString to be inspected for deduplication
+ // and be inserted into the deduplication hashtable.
+ forceDeduplication(ageThreshold, FullGC);
+
+ // Wait for deduplication to occur
+ while (getValue(dupString1) != getValue(baseString)) {
+ System.out.println("Waiting...");
+ try {
+ Thread.sleep(100);
+ } catch (Exception e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ // Create a new duplicate of baseString
+ StringBuilder sb2 = new StringBuilder(baseString);
+ String dupString2 = sb2.toString();
+ if (getValue(dupString2) == getValue(baseString)) {
+ throw new RuntimeException("Values should not match");
+ }
+
+ // Intern the new duplicate
+ Object beforeInternedValue = getValue(dupString2);
+ String internedString = dupString2.intern();
+ if (internedString != dupString2) {
+ throw new RuntimeException("String should match");
+ }
+ if (getValue(internedString) != getValue(baseString)) {
+ throw new RuntimeException("Values should match");
+ }
+
+ // Check original value of interned string, to make sure
+ // deduplication happened on the interned string and not
+ // on the base string
+ if (beforeInternedValue == getValue(baseString)) {
+ throw new RuntimeException("Values should not match");
+ }
+
+ System.out.println("End: InternedTest");
+ }
+
+ public static OutputAnalyzer run() throws Exception {
+ return runTest("-XX:+PrintGC",
+ "-XX:+PrintGCDetails",
+ "-XX:+UseStringDeduplication",
+ "-XX:+PrintStringDeduplicationStatistics",
+ "-XX:StringDeduplicationAgeThreshold=" + DefaultAgeThreshold,
+ InternedTest.class.getName(),
+ "" + DefaultAgeThreshold);
+ }
+ }
+
+ private static class MemoryUsageTest {
+ public static void main(String[] args) {
+ System.out.println("Begin: MemoryUsageTest");
+
+ final boolean useStringDeduplication = Boolean.parseBoolean(args[0]);
+ final int numberOfStrings = LargeNumberOfStrings;
+ final int numberOfUniqueStrings = 1;
+
+ ArrayList<String> list = createStrings(numberOfStrings, numberOfUniqueStrings);
+ forceDeduplication(DefaultAgeThreshold, FullGC);
+
+ if (useStringDeduplication) {
+ verifyStrings(list, numberOfUniqueStrings);
+ }
+
+ System.gc();
+ System.out.println("Heap Memory Usage: " + ManagementFactory.getMemoryMXBean().getHeapMemoryUsage().getUsed());
+
+ System.out.println("End: MemoryUsageTest");
+ }
+
+ public static OutputAnalyzer run(boolean useStringDeduplication) throws Exception {
+ String[] extraArgs = new String[0];
+
+ if (useStringDeduplication) {
+ extraArgs = new String[] {
+ "-XX:+UseStringDeduplication",
+ "-XX:+PrintStringDeduplicationStatistics",
+ "-XX:StringDeduplicationAgeThreshold=" + DefaultAgeThreshold
+ };
+ }
+
+ String[] defaultArgs = new String[] {
+ "-XX:+PrintGC",
+ "-XX:+PrintGCDetails",
+ MemoryUsageTest.class.getName(),
+ "" + useStringDeduplication
+ };
+
+ ArrayList<String> args = new ArrayList<String>();
+ args.addAll(Arrays.asList(extraArgs));
+ args.addAll(Arrays.asList(defaultArgs));
+
+ return runTest(args.toArray(new String[args.size()]));
+ }
+ }
+
+ /*
+ * Tests
+ */
+
+ private static final int LargeNumberOfStrings = 10000;
+ private static final int SmallNumberOfStrings = 10;
+
+ private static final int MaxAgeThreshold = 15;
+ private static final int DefaultAgeThreshold = 3;
+ private static final int MinAgeThreshold = 1;
+
+ private static final int TooLowAgeThreshold = MinAgeThreshold - 1;
+ private static final int TooHighAgeThreshold = MaxAgeThreshold + 1;
+
+ public static void testYoungGC() throws Exception {
+ // Do young GC to age strings to provoke deduplication
+ OutputAnalyzer output = DeduplicationTest.run(LargeNumberOfStrings,
+ DefaultAgeThreshold,
+ YoungGC,
+ "-XX:+PrintGC",
+ "-XX:+PrintStringDeduplicationStatistics");
+ output.shouldNotContain("Full GC");
+ output.shouldContain("GC pause (G1 Evacuation Pause) (young)");
+ output.shouldContain("GC concurrent-string-deduplication");
+ output.shouldContain("Deduplicated:");
+ output.shouldHaveExitValue(0);
+ }
+
+ public static void testFullGC() throws Exception {
+ // Do full GC to age strings to provoke deduplication
+ OutputAnalyzer output = DeduplicationTest.run(LargeNumberOfStrings,
+ DefaultAgeThreshold,
+ FullGC,
+ "-XX:+PrintGC",
+ "-XX:+PrintStringDeduplicationStatistics");
+ output.shouldNotContain("GC pause (G1 Evacuation Pause) (young)");
+ output.shouldContain("Full GC");
+ output.shouldContain("GC concurrent-string-deduplication");
+ output.shouldContain("Deduplicated:");
+ output.shouldHaveExitValue(0);
+ }
+
+ public static void testTableResize() throws Exception {
+ // Test with StringDeduplicationResizeALot
+ OutputAnalyzer output = DeduplicationTest.run(LargeNumberOfStrings,
+ DefaultAgeThreshold,
+ YoungGC,
+ "-XX:+PrintGC",
+ "-XX:+PrintStringDeduplicationStatistics",
+ "-XX:+StringDeduplicationResizeALot");
+ output.shouldContain("GC concurrent-string-deduplication");
+ output.shouldContain("Deduplicated:");
+ output.shouldNotContain("Resize Count: 0");
+ output.shouldHaveExitValue(0);
+ }
+
+ public static void testTableRehash() throws Exception {
+ // Test with StringDeduplicationRehashALot
+ OutputAnalyzer output = DeduplicationTest.run(LargeNumberOfStrings,
+ DefaultAgeThreshold,
+ YoungGC,
+ "-XX:+PrintGC",
+ "-XX:+PrintStringDeduplicationStatistics",
+ "-XX:+StringDeduplicationRehashALot");
+ output.shouldContain("GC concurrent-string-deduplication");
+ output.shouldContain("Deduplicated:");
+ output.shouldNotContain("Rehash Count: 0");
+ output.shouldNotContain("Hash Seed: 0x0");
+ output.shouldHaveExitValue(0);
+ }
+
+ public static void testAgeThreshold() throws Exception {
+ OutputAnalyzer output;
+
+ // Test with max age theshold
+ output = DeduplicationTest.run(SmallNumberOfStrings,
+ MaxAgeThreshold,
+ YoungGC,
+ "-XX:+PrintGC",
+ "-XX:+PrintStringDeduplicationStatistics");
+ output.shouldContain("GC concurrent-string-deduplication");
+ output.shouldContain("Deduplicated:");
+ output.shouldHaveExitValue(0);
+
+ // Test with min age theshold
+ output = DeduplicationTest.run(SmallNumberOfStrings,
+ MinAgeThreshold,
+ YoungGC,
+ "-XX:+PrintGC",
+ "-XX:+PrintStringDeduplicationStatistics");
+ output.shouldContain("GC concurrent-string-deduplication");
+ output.shouldContain("Deduplicated:");
+ output.shouldHaveExitValue(0);
+
+ // Test with too low age threshold
+ output = DeduplicationTest.run(SmallNumberOfStrings,
+ TooLowAgeThreshold,
+ YoungGC);
+ output.shouldContain("StringDeduplicationAgeThreshold of " + TooLowAgeThreshold +
+ " is invalid; must be between " + MinAgeThreshold + " and " + MaxAgeThreshold);
+ output.shouldHaveExitValue(1);
+
+ // Test with too high age threshold
+ output = DeduplicationTest.run(SmallNumberOfStrings,
+ TooHighAgeThreshold,
+ YoungGC);
+ output.shouldContain("StringDeduplicationAgeThreshold of " + TooHighAgeThreshold +
+ " is invalid; must be between " + MinAgeThreshold + " and " + MaxAgeThreshold);
+ output.shouldHaveExitValue(1);
+ }
+
+ public static void testPrintOptions() throws Exception {
+ OutputAnalyzer output;
+
+ // Test without PrintGC and without PrintStringDeduplicationStatistics
+ output = DeduplicationTest.run(SmallNumberOfStrings,
+ DefaultAgeThreshold,
+ YoungGC);
+ output.shouldNotContain("GC concurrent-string-deduplication");
+ output.shouldNotContain("Deduplicated:");
+ output.shouldHaveExitValue(0);
+
+ // Test with PrintGC but without PrintStringDeduplicationStatistics
+ output = DeduplicationTest.run(SmallNumberOfStrings,
+ DefaultAgeThreshold,
+ YoungGC,
+ "-XX:+PrintGC");
+ output.shouldContain("GC concurrent-string-deduplication");
+ output.shouldNotContain("Deduplicated:");
+ output.shouldHaveExitValue(0);
+ }
+
+ public static void testInterned() throws Exception {
+ // Test that interned strings are deduplicated before being interned
+ OutputAnalyzer output = InternedTest.run();
+ output.shouldHaveExitValue(0);
+ }
+
+ public static void testMemoryUsage() throws Exception {
+ // Test that memory usage is reduced after deduplication
+ OutputAnalyzer output;
+ final String usagePattern = "Heap Memory Usage: (\\d+)";
+
+ // Run without deduplication
+ output = MemoryUsageTest.run(false);
+ output.shouldHaveExitValue(0);
+ final long memoryUsageWithoutDedup = Long.parseLong(output.firstMatch(usagePattern, 1));
+
+ // Run with deduplication
+ output = MemoryUsageTest.run(true);
+ output.shouldHaveExitValue(0);
+ final long memoryUsageWithDedup = Long.parseLong(output.firstMatch(usagePattern, 1));
+
+ // Calculate expected memory usage with deduplication enabled. This calculation does
+ // not take alignment and padding into account, so it's a conservative estimate.
+ final long sizeOfChar = 2; // bytes
+ final long bytesSaved = (LargeNumberOfStrings - 1) * (StringLength * sizeOfChar + unsafe.ARRAY_CHAR_BASE_OFFSET);
+ final long memoryUsageWithDedupExpected = memoryUsageWithoutDedup - bytesSaved;
+
+ System.out.println("Memory usage summary:");
+ System.out.println(" memoryUsageWithoutDedup: " + memoryUsageWithoutDedup);
+ System.out.println(" memoryUsageWithDedup: " + memoryUsageWithDedup);
+ System.out.println(" memoryUsageWithDedupExpected: " + memoryUsageWithDedupExpected);
+
+ if (memoryUsageWithDedup > memoryUsageWithDedupExpected) {
+ throw new Exception("Unexpected memory usage, memoryUsageWithDedup should less or equal to memoryUsageWithDedupExpected");
+ }
+ }
+}