From 8b4acb683183f945e785677b406460847bbd46be Mon Sep 17 00:00:00 2001
From: Lorenzo Gabriele <lorenzolespaul@gmail.com>
Date: Mon, 28 Sep 2026 13:29:10 +0200
Subject: [PATCH 1/3] fix: derive node heap limit from cgroup memory at startup

Hardcoded --max-old-space-size=4608 assumed a fixed container memory
limit, causing heavy GC thrash (minutes of scavenge/mark-sweep) before
the process finally OOM-crashes when the actual k8s limit differs.
Reading process.constrainedMemory() at entrypoint time sets the heap
ceiling to 75% of the real cgroup limit, so V8 hits the fatal
threshold sooner and the pod restarts faster.
---
 Dockerfile       |  1 +
 compute-heap.mjs | 11 +++++++++++
 entrypoint.sh    |  4 +++-
 3 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 compute-heap.mjs

diff --git a/Dockerfile b/Dockerfile
index f4720dec2..1f0974cad 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -19,6 +19,7 @@ COPY --from=builder --chown=docker:docker docs docs
 COPY --from=builder node_modules node_modules
 COPY  --chown=docker:docker tsconfig.src.json tsconfig.json
 COPY entrypoint.sh entrypoint.sh
+COPY compute-heap.mjs compute-heap.mjs
 
 RUN adduser -u 2004 -D docker &&\
     chmod +x entrypoint.sh
diff --git a/compute-heap.mjs b/compute-heap.mjs
new file mode 100644
index 000000000..2dbb8de18
--- /dev/null
+++ b/compute-heap.mjs
@@ -0,0 +1,11 @@
+import os from "node:os";
+
+const constrained =
+  typeof process.constrainedMemory === "function"
+    ? process.constrainedMemory()
+    : 0;
+const limitBytes = constrained || os.totalmem();
+const limitMB = Math.floor(limitBytes / 1024 / 1024);
+const heapMB = Math.floor(limitMB * 0.75);
+
+process.stdout.write(String(heapMB));
diff --git a/entrypoint.sh b/entrypoint.sh
index b269ddafd..d3f5c6f1f 100644
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
+HEAP_MB=$(node /compute-heap.mjs)
+
 exec node \
-  --max-old-space-size=4608 \
+  --max-old-space-size="${HEAP_MB}" \
   --max-semi-space-size=128 \
   /dist/src/index.js

From f6f149eb54b0102e849f0ae13224286637560353 Mon Sep 17 00:00:00 2001
From: Lorenzo Gabriele <lorenzolespaul@gmail.com>
Date: Mon, 28 Sep 2026 13:50:20 +0200
Subject: [PATCH 2/3] fix: Add compute-heap.mjs to .dockerignore

---
 .dockerignore | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.dockerignore b/.dockerignore
index 97285a9a1..db7aef61f 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -9,6 +9,7 @@
 !/tsconfig.json
 !/tsconfig.src.json
 !/entrypoint.sh
+!/compute-heap.mjs
 
 # Ignore unnecessary files inside allowed directories
 # This should go after the allowed directories

From 04c30377d3b285f32347900a5282499e5eae3974 Mon Sep 17 00:00:00 2001
From: Lorenzo Gabriele <lorenzolespaul@gmail.com>
Date: Mon, 28 Sep 2026 14:38:26 +0200
Subject: [PATCH 3/3] fix: derive semi-space size from cgroup budget too

max-semi-space-size was still fixed at 128MB, additive on top of the
derived old-space size. Since new-space is two semi-spaces, its
worst-case footprint (2x the flag value) could push total V8 heap
past the cgroup limit. Now both old-space and semi-space are sized
from the same memory budget, with new-space reserved first.
---
 compute-heap.mjs | 14 ++++++++++++--
 entrypoint.sh    |  6 ++++--
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/compute-heap.mjs b/compute-heap.mjs
index 2dbb8de18..45473cde2 100644
--- a/compute-heap.mjs
+++ b/compute-heap.mjs
@@ -6,6 +6,16 @@ const constrained =
     : 0;
 const limitBytes = constrained || os.totalmem();
 const limitMB = Math.floor(limitBytes / 1024 / 1024);
-const heapMB = Math.floor(limitMB * 0.75);
 
-process.stdout.write(String(heapMB));
+// Reserve 25% headroom for non-V8-heap usage (native buffers, stack, code space, RSS overhead).
+const budgetMB = Math.floor(limitMB * 0.75);
+
+// V8's new-space is TWO semi-spaces (from-space + to-space), so its worst-case
+// footprint is 2x --max-semi-space-size. Size it as a fraction of the budget,
+// clamped to V8's own sane range, then subtract it before sizing old-space so
+// old-space + new-space never exceeds the budget.
+const semiSpaceMB = Math.min(128, Math.max(16, Math.floor(budgetMB * 0.05)));
+const newSpaceMB = semiSpaceMB * 2;
+const oldSpaceMB = Math.max(1, budgetMB - newSpaceMB);
+
+process.stdout.write(`${oldSpaceMB} ${semiSpaceMB}`);
diff --git a/entrypoint.sh b/entrypoint.sh
index d3f5c6f1f..cf54c93fd 100644
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -1,8 +1,10 @@
 #!/bin/sh
 
-HEAP_MB=$(node /compute-heap.mjs)
+read -r HEAP_MB SEMI_MB <<EOF
+$(node /compute-heap.mjs)
+EOF
 
 exec node \
   --max-old-space-size="${HEAP_MB}" \
-  --max-semi-space-size=128 \
+  --max-semi-space-size="${SEMI_MB}" \
   /dist/src/index.js