From 3ce26e3df2038f2500f502823cbac4cbd2c28703 Mon Sep 17 00:00:00 2001
From: u9g <git@u9g.dev>
Date: Tue, 8 Sep 2026 10:25:57 -0400
Subject: [PATCH] Throttle repeated packet-parse error logs in FullPacketParser

A malformed or mismatched stream can make the same packet fail to parse on
every frame it sends. FullPacketParser logged the full stack each time, so
one persistent fault produced thousands of identical stacks a minute and
buried every other log line -- a single session was seen writing ~15k
identical PartialReadError stacks, tens of megabytes.

Each distinct error (keyed on the top of its stack) is now logged in full
on its first occurrence, then only at the 1st, 2nd, 4th, 8th, ... with a
repeat count, so a persistent fault costs O(log n) lines instead of n. The
same throttle covers the chunk-size-mismatch log two lines up. Counts are
per parser instance; noErrorLogging still silences everything.
---
 src/serializer.js | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/serializer.js b/src/serializer.js
index 8b52e95..9d35018 100644
--- a/src/serializer.js
+++ b/src/serializer.js
@@ -1,5 +1,15 @@
 const Transform = require('readable-stream').Transform
 
+// A malformed stream can make the same packet fail to parse for every frame it sends -- thousands
+// of identical stacks a minute. Log the first occurrence of each in full, then only at 1, 2, 4, 8,
+// ... so a persistent fault stays O(log n) instead of unbounded. Keyed per parser instance.
+function logThrottled (counts, key, full) {
+  const n = (counts.get(key) || 0) + 1
+  counts.set(key, n)
+  if (n === 1) console.log(full)
+  else if ((n & (n - 1)) === 0) console.log(`${key} (repeated ${n} times)`)
+}
+
 class Serializer extends Transform {
   constructor (proto, mainType) {
     super({ writableObjectMode: true })
@@ -62,6 +72,7 @@ class FullPacketParser extends Transform {
     this.proto = proto
     this.mainType = mainType
     this.noErrorLogging = noErrorLogging
+    this.errorCounts = new Map()
   }
 
   parsePacketBuffer (buffer) {
@@ -73,13 +84,14 @@ class FullPacketParser extends Transform {
     try {
       packet = this.parsePacketBuffer(chunk)
       if (packet.metadata.size !== chunk.length && !this.noErrorLogging) {
-        console.log('Chunk size is ' + chunk.length + ' but only ' + packet.metadata.size + ' was read ; partial packet : ' +
+        logThrottled(this.errorCounts, 'chunk size mismatch',
+          'Chunk size is ' + chunk.length + ' but only ' + packet.metadata.size + ' was read ; partial packet : ' +
           JSON.stringify(packet.data) + '; buffer :' + chunk.toString('hex'))
       }
     } catch (e) {
       if (e.partialReadError) {
         if (!this.noErrorLogging) {
-          console.log(e.stack)
+          logThrottled(this.errorCounts, e.stack.split('\n')[0], e.stack)
         }
         return cb()
       } else {