Add demo for JEP 377 – ZGC: A Scalable Low-Latency GC (Java 15)

src/main/java/org/javademos/init/Java15.java

@@ -9,6 +9,7 @@
 import org.javademos.java15.jep372.NashornRemovalDemo;
 import org.javademos.java15.jep373.DatagramSocketDemo15;
 import org.javademos.java15.jep375.InstanceofPatternMatchingSecondPreview;
+import org.javademos.java15.jep377.ZGarbageCollectorDemo;
 import org.javademos.java15.jep381.SolarisSparcRemovalDemo;
 import org.javademos.java15.jep383.ForeignMemoryAccessDemo;
 import org.javademos.java15.jep384.RecordsSecondPreviewDemo;
@@ -34,6 +35,8 @@ public static ArrayList<IDemo> getDemos() {
         java15DemoPool.add(new DatagramSocketDemo15());
         // JEP 375
         java15DemoPool.add(new InstanceofPatternMatchingSecondPreview());
+        // JEP 377
+        java15DemoPool.add(new ZGarbageCollectorDemo());
         // JEP 381
         java15DemoPool.add(new SolarisSparcRemovalDemo());
         // JEP 383

src/main/java/org/javademos/java15/jep377/ZGarbageCollectorDemo.java

@@ -0,0 +1,60 @@
+package org.javademos.java15.jep377;
+
+import org.javademos.commons.IDemo;
+
+/// Demo for JDK 15 feature JEP 377 – ZGC: A Scalable Low-Latency Garbage Collector.
+///
+/// JEP history:
+/// - JDK 15: [JEP 377 - ZGC: A Scalable Low-Latency Garbage Collector](https://openjdk.org/jeps/377)
+/// - JDK 11: [JEP 333 - ZGC: A Scalable Low-Latency Garbage Collector (Experimental)](https://openjdk.org/jeps/333)
+///
+/// Further reading:
+/// - [Java ZGC Overview](https://www.baeldung.com/jvm-zgc)
+/// - [Inside Java – The Z Garbage Collector](https://inside.java/2020/06/29/zgc-production/)
+///
+/// @author  wassef
+
+public class ZGarbageCollectorDemo  implements IDemo {
+
+    @Override
+    public void demo() {
+        info(377);
+
+        // ZGC (Z Garbage Collector) is a scalable, low-latency garbage collector
+        // introduced experimentally in Java 11 (JEP 333) and promoted to production
+        // in Java 15 (JEP 377).
+
+        // Its design goal is to keep GC pause times consistently under 10 ms,
+        // regardless of heap size — even for multi-terabyte heaps.
+        // To achieve this, ZGC performs all heavy operations (marking, relocation,
+        // and remapping) concurrently with the running application threads.
+
+        // Core characteristics:
+        // - Pause times: typically < 10 ms, independent of heap size
+        // - Scalable: supports heaps up to multiple TB
+        // - Compacting: prevents fragmentation while staying concurrent
+        // - Load-barrier based, using “colored pointers” to track object state
+
+        // Suitable for:
+        // - Latency-sensitive systems (e.g. trading, analytics)
+        // - Applications requiring large heaps and predictable response times
+
+        // --- Usage examples ---
+
+        // Enable ZGC (basic):
+        //   java -XX:+UseZGC -Xmx4g -Xms4g -jar myapp.jar
+
+        // Enable detailed GC logging:
+        //   java -XX:+UseZGC -Xlog:gc* -jar myapp.jar
+
+        // Optional tuning flags:
+        //   -XX:SoftMaxHeapSize=2g     # soft heap limit for adaptive resizing
+        //   -Xlog:gc+heap=debug        # show region allocation details
+
+        // Supported platforms (as of JDK 15):
+        //   • Linux/x64
+        //   • Windows/x64
+        //   • macOS/x64
+        //   • Linux/AArch64
+    }
+}

src/main/resources/JDK15Info.json

@@ -47,6 +47,14 @@
     "link": true,
     "code": false
   },
+  {
+    "number": 377,
+    "jdk": 15,
+    "name": "ZGC: A Scalable Low-Latency Garbage Collector",
+    "description": "Production-ready low-latency garbage collector maintaining sub-10ms pause times for large heaps.",
+    "link": false,
+    "code": false
+  },
   {
     "jep": 381,
     "jdk": 15,