From b14ee4e925e321d02945e9d46c54da4f3a14f985 Mon Sep 17 00:00:00 2001
From: Roman Krasiuk <rokrassyuk@gmail.com>
Date: Fri, 24 Feb 2023 10:13:18 +0200
Subject: [PATCH] perf(download): parallel header sealing (#1536)

---
 Cargo.lock                                            | 1 +
 crates/net/downloaders/Cargo.toml                     | 1 +
 crates/net/downloaders/src/headers/reverse_headers.rs | 6 +++---
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 59bcee4bf..898170dfa 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4506,6 +4506,7 @@ dependencies = [
  "itertools 0.10.5",
  "metrics",
  "pin-project",
+ "rayon",
  "reth-db",
  "reth-eth-wire",
  "reth-interfaces",
diff --git a/crates/net/downloaders/Cargo.toml b/crates/net/downloaders/Cargo.toml
index cb7d8fc2b..76a7fc67a 100644
--- a/crates/net/downloaders/Cargo.toml
+++ b/crates/net/downloaders/Cargo.toml
@@ -26,6 +26,7 @@ tokio-stream = "0.1"
 # misc
 tracing = "0.1.37"
 metrics = "0.20.1"
+rayon = "1.6.0"
 
 # optional deps for the test-utils feature
 thiserror = { version = "1", optional = true }
diff --git a/crates/net/downloaders/src/headers/reverse_headers.rs b/crates/net/downloaders/src/headers/reverse_headers.rs
index 8bcf9031d..5e0f869b6 100644
--- a/crates/net/downloaders/src/headers/reverse_headers.rs
+++ b/crates/net/downloaders/src/headers/reverse_headers.rs
@@ -4,6 +4,7 @@ use super::task::TaskDownloader;
 use crate::metrics::DownloaderMetrics;
 use futures::{stream::Stream, FutureExt};
 use futures_util::{stream::FuturesUnordered, StreamExt};
+use rayon::prelude::*;
 use reth_interfaces::{
     consensus::Consensus,
     p2p::{
@@ -200,9 +201,8 @@ where
         let sync_target_hash = self.existing_sync_target_hash();
         let mut validated = Vec::with_capacity(headers.len());
 
-        for parent in headers {
-            let parent = parent.seal_slow();
-
+        let sealed_headers = headers.into_par_iter().map(|h| h.seal_slow()).collect::<Vec<_>>();
+        for parent in sealed_headers {
             // Validate that the header is the parent header of the last validated header.
             if let Some(validated_header) =
                 validated.last().or_else(|| self.lowest_validated_header())