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
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+== JDK 25 
+java 25.0.4.1  compact headers: false
+  id          offset 16
+  priceCents  offset 12
+  stock       offset 24
+  active      offset 28
+  sku         offset 32
+  first field starts at byte 12  (so the header is at most 12 bytes)
+  a hard-coded 12-byte header would be right here
+
+== JDK 26 
+java 26.0.2.1  compact headers: false
+  id          offset 16
+  priceCents  offset 12
+  stock       offset 24
+  active      offset 28
+  sku         offset 32
+  first field starts at byte 12  (so the header is at most 12 bytes)
+  a hard-coded 12-byte header would be right here
+
+== JDK 27 
+java 27  compact headers: true
+  id          offset  8
+  priceCents  offset 16
+  stock       offset 20
+  active      offset 24
+  sku         offset 28
+  first field starts at byte 8  (so the header is at most 8 bytes)
+  a hard-coded 12-byte header would be WRONG here
+
+== JDK 27 -XX:-UseCompactObjectHeaders
+java 27  compact headers: false
+  id          offset 16
+  priceCents  offset 12
+  stock       offset 24
+  active      offset 28
+  sku         offset 32
+  first field starts at byte 12  (so the header is at most 12 bytes)
+  a hard-coded 12-byte header would be right here
+