Enable String Deduplication on JDK 17+ (#1380)

Enable String Deduplication on JDK 17+ G1 and Shenandoah GC support string deduplication as of JDK 17 * https://openjdk.java.net/jeps/192 * https://bugs.openjdk.org/browse/JDK-8264718 Only enable on JDK 17+ due to fix https://bugs.openjdk.org/browse/JDK-8277981 JDK 18+ enable string deduplication for SerialGC, ParallalGC, and ZGC. https://malloc.se/blog/zgc-jdk18
palantir · Mar 15, 2023 · 902de8d · 902de8d
1 parent 33a7c9e
commit 902de8d
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diff --git a/changelog/@unreleased/pr-1380.v2.yml b/changelog/@unreleased/pr-1380.v2.yml
@@ -0,0 +1,19 @@
+type: improvement
+improvement:
+  description: |-
+    Enable String Deduplication on JDK 17+
+
+    G1 and Shenandoah GC support string deduplication as of JDK 17
+    * https://openjdk.java.net/jeps/192
+    * https://bugs.openjdk.org/browse/JDK-8264718
+
+    Only enable on JDK 17+ due to fix
+    https://bugs.openjdk.org/browse/JDK-8277981
+
+    JDK 18+ enable string deduplication for SerialGC, ParallalGC, and ZGC.
+    https://malloc.se/blog/zgc-jdk18
+  links:
+  - https://github.com/palantir/sls-packaging/pull/1380
+  - https://openjdk.java.net/jeps/192
+  - https://bugs.openjdk.org/browse/JDK-8264718
+  - https://malloc.se/blog/zgc-jdk18
diff --git a/gradle-sls-packaging/src/main/java/com/palantir/gradle/dist/service/tasks/LaunchConfig.java b/gradle-sls-packaging/src/main/java/com/palantir/gradle/dist/service/tasks/LaunchConfig.java
@@ -60,6 +60,10 @@ public final class LaunchConfig {
             ImmutableList.of("-XX:+ShowCodeDetailsInExceptionMessages");
     private static final ImmutableList<String> java15Options =
             ImmutableList.of("-XX:+UnlockDiagnosticVMOptions", "-XX:+ExpandSubTypeCheckAtParseTime");
+
+    private static final ImmutableList<String> java17PlusOptions = ImmutableList.of(
+            "-XX:+UseStringDeduplication"); // only enable on JDK 17+ due to https://bugs.openjdk.org/browse/JDK-8277981
+
     private static final ImmutableList<String> disableBiasedLocking = ImmutableList.of("-XX:-UseBiasedLocking");
     // Disable C2 compilation for problematic structure in JDK 11.0.16, see https://bugs.openjdk.org/browse/JDK-8291665
     private static final ImmutableList<String> jdk11DisableC2Compile =
@@ -175,6 +179,10 @@ static void action(Params params) {
                                 javaVersion.compareTo(JavaVersion.toVersion("15")) == 0
                                         ? java15Options
                                         : ImmutableList.of())
+                        .addAllJvmOpts(
+                                javaVersion.compareTo(JavaVersion.toVersion("17")) >= 0
+                                        ? java17PlusOptions
+                                        : ImmutableList.of())
                         // Biased locking is disabled on java 15+ https://openjdk.java.net/jeps/374
                         // We disable biased locking on all releases in order to reduce safepoint time,
                         // revoking biased locks requires a safepoint, and can occur for non-obvious