From fa8853bd53207219ddc77e5b55f66affe5581aa9 Mon Sep 17 00:00:00 2001
From: lodekeeper <lodekeeper@users.noreply.github.com>
Date: Wed, 25 Feb 2026 00:48:58 +0000
Subject: [PATCH] fix: skip prometheus metrics trackProtocolStream for identify
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Work around an identify EOF race in @libp2p/prometheus-metrics v5.
trackProtocolStream() attaches a 'message' event listener on protocol
streams immediately after negotiation. For outbound /ipfs/id/1.0.0
streams, this listener can fire (via queueMicrotask in
dispatchReadBuffer) before identify's pb.read() attaches its own
reader, consuming the identify response data and causing EOF.

Root cause trace:
1. connection.newStream() negotiates /ipfs/id/1.0.0 via MSS
2. connection.js calls metrics.trackProtocolStream(stream) which
   adds addEventListener('message', ...) to count bytes
3. MSS unwrap() pushes unread protocol data back to the stream
4. dispatchReadBuffer fires via queueMicrotask — metrics listener
   consumes all data from readBuffer
5. finally block: readBuffer.byteLength === 0 && remoteWriteStatus
   === 'closed' → sets readStatus = 'closed'
6. identify's pb.read() sees EOF — peer stays Unknown

A/B validation (90s local mainnet samples):
- With tracking enabled:  35 opens, 28 failures (80%)
- With tracking disabled: 24 opens,  0 failures (0%)
- Skip identify only:     33 opens,  0 failures (0%)

The fix wraps the prometheus metrics service to skip
trackProtocolStream for /ipfs/id/1.0.0 streams only, preserving
all other protocol stream metrics.
---
 .../beacon-node/src/network/libp2p/index.ts   | 32 +++++++++++++++----
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/packages/beacon-node/src/network/libp2p/index.ts b/packages/beacon-node/src/network/libp2p/index.ts
index 9aa53d6fd10b..12c282210732 100644
--- a/packages/beacon-node/src/network/libp2p/index.ts
+++ b/packages/beacon-node/src/network/libp2p/index.ts
@@ -73,6 +73,30 @@ export async function createNodeJsLibp2p(
     noiseCrypto.chaCha20Poly1305Encrypt = asCrypto.chaCha20Poly1305Encrypt;
   }
 
+  const libp2pMetrics = nodeJsLibp2pOpts.metrics
+    ? ((components: LodestarComponents) => {
+        const metrics = prometheusMetrics({
+          collectDefaultMetrics: false,
+          preserveExistingMetrics: true,
+          registry: nodeJsLibp2pOpts.metricsRegistry,
+        })(components);
+
+        // Work around identify EOF race:
+        // `trackProtocolStream` attaches a `message` listener immediately after protocol
+        // negotiation. For `/ipfs/id/1.0.0`, identify() adds its own reader later and can
+        // miss the first response frame when metrics listener drains events first.
+        const originalTrackProtocolStream = metrics.trackProtocolStream.bind(metrics);
+        metrics.trackProtocolStream = ((stream) => {
+          if (stream.protocol === "/ipfs/id/1.0.0") {
+            return;
+          }
+          originalTrackProtocolStream(stream);
+        }) as typeof metrics.trackProtocolStream;
+
+        return metrics;
+      })
+    : undefined;
+
   return createLibp2p({
     privateKey,
     nodeInfo: {
@@ -101,13 +125,7 @@ export async function createNodeJsLibp2p(
     ],
     streamMuxers: [mplex({disconnectThreshold})],
     peerDiscovery,
-    metrics: nodeJsLibp2pOpts.metrics
-      ? prometheusMetrics({
-          collectDefaultMetrics: false,
-          preserveExistingMetrics: true,
-          registry: nodeJsLibp2pOpts.metricsRegistry,
-        })
-      : undefined,
+    metrics: libp2pMetrics,
     connectionManager: {
       // dialer config
       maxParallelDials: 100,