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 +1,44 @@
+#!/usr/bin/env bash
+# JEP 523 in a small container: 1 CPU, 1 GB. JDK 26 picks Serial here, JDK 27 picks G1. What does the app
+# cost under each collector, and what does the JVM say it spends outside the heap (Native Memory Tracking)?
+# usage: one-cpu.sh [N products] [runs]
+source "$(dirname "$0")/lib.sh"
+N="${1:-2000000}"; RUNS="${2:-3}"
+TMP="$(mktemp -d)"
+MB=$((1024*1024))
+export NMT=1 CG_MEM=$((1024*MB)) CG_CPUS=1
+
+nmt() {  # file -> "GC committed KB|Total committed KB"
+  local gc tot
+  gc=$(awk '/^-  *GC \(reserved/ {gsub(/[^0-9=]/," "); n=split($0,a,"="); print a[3]+0; exit}' "$1")
+  tot=$(awk '/^Total: reserved/ {gsub(/[^0-9=]/," "); n=split($0,a,"="); print a[3]+0; exit}' "$1")
+  echo "$gc|$tot"
+}
+
+row() {  # label jdk flags...
+  local label="$1" jh="$2"; shift 2
+  local st=() live=() rss=() gcn=() gcms=() ld=() gck=() totk=() coll="" cpus=""
+  for r in $(seq 1 "$RUNS"); do
+    d="$TMP/$label-$r"
+    run_app "$jh" "$N" "$d" -XX:MaxRAMPercentage=50 "$@" >/dev/null 2>&1 || { echo "$label run $r FAILED: $(cat "$d/outcome.txt")"; return; }
+    coll=$(kv "$d/memory.txt" collectors); cpus=$(kv "$d/memory.txt" availableProcessors)
+    st+=("$(grep -o '[0-9.]*' "$d/startup.txt" | tail -1)")
+    live+=("$(kv "$d/memory.txt" heapLiveAfterGcMB)"); rss+=("$(kv "$d/memory.txt" rssMB)")
+    gcn+=("$(kv "$d/load.txt" gcCountDuringLoad)"); gcms+=("$(kv "$d/load.txt" gcMillisDuringLoad)")
+    ld+=("$(kv "$d/load.txt" loadMillis)")
+    IFS='|' read -r g t <<<"$(nmt "$d/nmt.txt")"; gck+=("$g"); totk+=("$t")
+  done
+  m() { printf '%s\n' "$@" | median; }
+  printf '%s\n  collectors=%s cpus=%s\n' "== $label" "$coll" "$cpus"
+  printf '  startup=%ss  live=%sMB  rss=%sMB  loadMillis=%s  gcDuringLoad=%s (%sms)\n' \
+    "$(m "${st[@]}")" "$(m "${live[@]}")" "$(m "${rss[@]}")" "$(m "${ld[@]}")" "$(m "${gcn[@]}")" "$(m "${gcms[@]}")"
+  printf '  NMT: GC committed=%s KB   Total committed=%s KB\n\n' "$(m "${gck[@]}")" "$(m "${totk[@]}")"
+}
+
+echo "# $N products, container = 1 GB / 1 CPU (cgroup), -XX:MaxRAMPercentage=50 (512 MB heap), NMT summary on, medians of $RUNS runs"
+row "jdk26-default (the JVM chose)"        "$JDK26"
+row "jdk26 -XX:+UseG1GC"                   "$JDK26" -XX:+UseG1GC
+row "jdk27-default (the JVM chose)"        "$JDK27"
+row "jdk27 -XX:+UseSerialGC"               "$JDK27" -XX:+UseSerialGC
+row "jdk27 -XX:+UseSerialGC, compact off"  "$JDK27" -XX:+UseSerialGC -XX:-UseCompactObjectHeaders
+rm -rf "$TMP"