Add jdk28-zgc: ZGC startup and warmup baseline on JDK 25/27/28-ea, and a probe for JEP 545/546

Spring Boot 4.1.1 harness measuring first-response time versus initial heap size and a 20,000-request warmup. Shows -XX:+ZAdaptiveHeapSizing is not yet in any build. Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_01WzVQ6zFh9cuLPj9RSbRH8U
2026-10-12 17:13:14 +00:00
parent 2f88734f5d
commit df13a904d7
11 changed files with 431 additions and 0 deletions
@@ -0,0 +1,37 @@
+import java.net.URI;
+import java.net.http.*;
+import java.util.*;
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.*;
+
+/** Fires TOTAL requests with THREADS threads and reports how long each batch of BATCH took. */
+public class Warmup {
+    public static void main(String[] a) throws Exception {
+        int port = Integer.parseInt(a[0]);
+        int total = 20_000, batch = 2_000, threads = 4;
+        HttpClient c = HttpClient.newBuilder().version(HttpClient.Version.HTTP_1_1).build();
+        HttpRequest rq = HttpRequest.newBuilder(URI.create("http://localhost:" + port + "/hello")).build();
+        AtomicInteger done = new AtomicInteger();
+        long[] batchEnd = new long[total / batch];
+        long t0 = System.nanoTime();
+        ExecutorService ex = Executors.newFixedThreadPool(threads);
+        List<Future<?>> fs = new ArrayList<>();
+        for (int t = 0; t < threads; t++) fs.add(ex.submit(() -> {
+            try {
+                while (true) {
+                    int n = done.incrementAndGet();
+                    if (n > total) return null;
+                    c.send(rq, HttpResponse.BodyHandlers.discarding());
+                    if (n % batch == 0) batchEnd[n / batch - 1] = System.nanoTime();
+                }
+            } catch (Exception e) { throw new RuntimeException(e); }
+        }));
+        for (Future<?> f : fs) f.get();
+        ex.shutdown();
+        StringBuilder sb = new StringBuilder("batch ms:");
+        long prev = t0;
+        for (long e : batchEnd) { sb.append(' ').append((e - prev) / 1_000_000); prev = e; }
+        System.out.println(sb);
+        System.out.println("total ms: " + (prev - t0) / 1_000_000);
+    }
+}