Add jdk27-memory: compact object headers and G1-everywhere on a Spring Boot service

Spring Boot 4.1.1 catalog service measured on JDK 25, 26 and 27: live heap 320 MB to 273 MB with compact headers, per-class bytes per instance, container-sizing sweeps with real cgroup limits, 1-CPU Serial vs G1 with Native Memory Tracking, removed flags (MaxRAM, UseCompressedClassPointers), and a kernel OOM-kill check. Outputs in jdk27-memory/output. Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01TF9JWFvJSNm6HVzswzZU5a
2026-09-24 15:09:55 +00:00
parent e189da79ba
commit e83c9949d8
29 changed files with 1041 additions and 0 deletions
@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+# The smallest container that can hold the catalog, before and after. For each memory limit the app is started
+# inside a cgroup with that limit and asked to load N products; the table says what happened.
+#   ok            the load finished
+#   java-OOM      the JVM threw OutOfMemoryError: the heap (a fraction of the limit) was too small
+#   killed(...)   the kernel killed the process: total memory, not just heap, went over the limit
+#   no-result-in-25s   the JVM stayed alive but the load (about a second when healthy) did not finish in 25
+#                 seconds: the heap is so tight that the collector runs continuously and makes no progress
+# Each cell is RUNS runs ("3/3 ok" = all three finished); a cell near the boundary can be mixed.
+# usage: container-sizing.sh [N products] [runs per cell]
+source "$(dirname "$0")/lib.sh"
+N="${1:-2000000}"; RUNS="${2:-3}"
+TMP="$(mktemp -d)"; RETRIES=0
+MB=$((1024*1024))
+
+sweep() {  # title, jvm-flags-for-all, limits...
+  local title="$1" common="$2"; shift 2
+  echo "== $title"
+  printf '%-8s %-8s %-30s %-30s %-30s\n' "limit" "heap" "JDK 26 default" "JDK 27 default" "JDK 27 opt-out"
+  for lim in "$@"; do
+    local cells=() heap="?"
+    for cfg in "26|$JDK26|" "27|$JDK27|" "27o|$JDK27|-XX:-UseCompactObjectHeaders"; do
+      IFS='|' read -r tag jh fl <<<"$cfg"
+      local ok=0 fails=() rss=()
+      for r in $(seq 1 "$RUNS"); do
+        d="$TMP/$tag-$lim-$r"
+        CG_MEM=$((lim*MB)) CG_CPUS=2 run_app "$jh" "$N" "$d" $common $fl >/dev/null 2>&1
+        h=$(kv "$d/memory-idle.txt" maxHeapMB); [ -n "$h" ] && heap="$h"
+        [ -f "$d/retries" ] && RETRIES=$((RETRIES+1))
+        out=$(cat "$d/outcome.txt")
+        if [ "$out" = ok ]; then ok=$((ok+1)); rss+=("$(kv "$d/memory.txt" rssMB)"); else fails+=("${out%%(*}"); fi
+      done
+      cell="$ok/$RUNS ok"
+      if [ $ok -gt 0 ]; then cell="$cell rss $(printf '%s\n' "${rss[@]}" | median)MB"; fi
+      if [ ${#fails[@]} -gt 0 ]; then cell="$cell [$(printf '%s\n' "${fails[@]}" | sort | uniq -c | awk '{printf "%s%sx %s",sep,$1,$2; sep=" "}')]"; fi
+      cells+=("$cell")
+    done
+    printf '%-8s %-8s %-30s %-30s %-30s\n' "${lim}MB" "${heap}MB" "${cells[0]}" "${cells[1]}" "${cells[2]}"
+  done
+  echo
+}
+
+#   ONLY=75 or ONLY=25 runs one of the two sweeps (each takes about 12 minutes); default is both.
+ONLY="${ONLY:-both}"
+echo "# $N products; 2 CPUs; $RUNS runs per cell; rss is the median of the runs that finished"
+if [ "$ONLY" != 25 ]; then
+  sweep "Heap set to 75% of the container (-XX:MaxRAMPercentage=75)" "-XX:MaxRAMPercentage=75" 400 416 432 448 512 704
+fi
+if [ "$ONLY" != 75 ]; then
+  sweep "Heap left at the JVM default (25% of the container)" "" 1024 1152 1216 1280 1536 2048
+fi
+echo "# runs that needed a startup retry (the JVM never came up, for a reason other than OOM or a kernel kill): $RETRIES"
+rm -rf "$TMP"