From 6dd8f0321405a930475dd0d79cc7d420f19eb04e Mon Sep 17 00:00:00 2001
From: Ricardo <rick@rmendes.net>
Date: Mon, 9 Mar 2026 17:25:05 +0100
Subject: [PATCH] fix(og): aggressive GC to prevent OOM in constrained
 containers

Full OG regeneration (2,350 images) was OOM-killed because WASM native
memory from Satori/Resvg accumulated between GC cycles. The previous
GC interval of 50 images allowed ~2.5-5 GB of native allocations before
reclamation. Reduce to every 5 images to keep peak RSS under ~400 MB.

Also reduce --max-old-space-size from 768 to 512 MB (V8 heap only uses
~22 MB) and add peak RSS tracking to the completion log.

Confab-Link: http://localhost:8080/sessions/edb1b7b0-da66-4486-bd9c-d1cfa7553b88
---
 eleventy.config.js |  2 +-
 lib/og.js          | 18 +++++++++++++-----
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/eleventy.config.js b/eleventy.config.js
index b8431ae..615871e 100644
--- a/eleventy.config.js
+++ b/eleventy.config.js
@@ -1123,7 +1123,7 @@ export default function (eleventyConfig) {
     const siteName = process.env.SITE_NAME || "My IndieWeb Blog";
     try {
       execFileSync(process.execPath, [
-        "--max-old-space-size=768",
+        "--max-old-space-size=512",
         "--expose-gc",
         resolve(__dirname, "lib", "og-cli.js"),
         contentDir,
diff --git a/lib/og.js b/lib/og.js
index 4feb24b..7b9d394 100644
--- a/lib/og.js
+++ b/lib/og.js
@@ -298,8 +298,13 @@ export async function generateOgImages(contentDir, cacheDir, siteName) {
   let skipped = 0;
   const newManifest = {};
   const SAVE_INTERVAL = 10;
-  const GC_INTERVAL = 50;
+  // GC every 5 images to keep WASM native memory bounded.
+  // Satori (Yoga WASM) + Resvg (Rust WASM) allocate ~50-100 MB native memory
+  // per image that V8 doesn't track. Without aggressive GC, native memory
+  // grows unbounded and OOM-kills the process in constrained containers.
+  const GC_INTERVAL = 5;
   const hasGC = typeof global.gc === "function";
+  let peakRss = 0;
 
   for (const filePath of mdFiles) {
     const raw = readFileSync(filePath, "utf8");
@@ -333,25 +338,28 @@ export async function generateOgImages(contentDir, cacheDir, siteName) {
     newManifest[slug] = { title: slug, hash };
     generated++;
 
-    // Save manifest periodically to preserve progress
+    // Save manifest periodically to preserve progress on OOM kill
     if (generated % SAVE_INTERVAL === 0) {
       writeFileSync(manifestPath, JSON.stringify(newManifest, null, 2));
     }
 
     // Force GC to reclaim Satori/Resvg WASM native memory.
     // V8 doesn't track native heap (Satori Yoga WASM + Resvg Rust WASM),
-    // so without periodic GC the JS wrappers accumulate and native memory
-    // grows unbounded. With --expose-gc this keeps peak RSS under control.
+    // so without frequent GC the JS wrappers accumulate and native memory
+    // grows unbounded. Every 5 images keeps peak RSS under ~400 MB.
     if (hasGC && generated % GC_INTERVAL === 0) {
       global.gc();
+      const rss = process.memoryUsage().rss;
+      if (rss > peakRss) peakRss = rss;
     }
   }
 
   if (hasGC) global.gc();
   writeFileSync(manifestPath, JSON.stringify(newManifest, null, 2));
   const mem = process.memoryUsage();
+  if (mem.rss > peakRss) peakRss = mem.rss;
   console.log(
     `[og] Generated ${generated} images, skipped ${skipped} (cached or have photos)` +
-    ` | RSS: ${(mem.rss / 1024 / 1024).toFixed(0)} MB, heap: ${(mem.heapUsed / 1024 / 1024).toFixed(0)} MB`,
+    ` | RSS: ${(mem.rss / 1024 / 1024).toFixed(0)} MB, peak: ${(peakRss / 1024 / 1024).toFixed(0)} MB, heap: ${(mem.heapUsed / 1024 / 1024).toFixed(0)} MB`,
   );
 }