1 files changed, 23 insertions, 1 deletions
diff --git a/src/swarm/sync.rs b/src/swarm/sync.rs
index 5a4cba4..868fead 100644
--- a/src/swarm/sync.rs
+++ b/src/swarm/sync.rs
@@ -11,7 +11,7 @@ use tokio::time::Instant;
 use tracing::{debug, info, trace, warn};
 
 use crate::locks::MutexExt;
-use crate::state::{AppState, Liveness, Standing};
+use crate::state::{AppState, Liveness, PeerState, Standing};
 use crate::swarm::peer::{peer_swarm, send_hello_once};
 use crate::swarm::source;
 use crate::swarm::throughput::SyncBytes;
@@ -190,6 +190,28 @@ async fn deliver_sync_to_peer(state: &AppState, peer: &str) -> Result<()> {
         (session, encoded)
     };
 
+    // Off the sync worker: a slow send (a large message, a busy Mycelium) mustn't hold
+    // up every other peer's. One message per peer is in flight (`sending`), so a peer's
+    // messages still go out in order.
+    let state = state.clone();
+    let peer = peer.to_owned();
+    tokio::spawn(async move {
+        if let Err(error) = send_generated(&state, &peer, &peer_state_mutex, session, encoded).await
+        {
+            warn!(peer = %peer, error = %format!("{error:#}"), "Synchronization processing failed");
+        }
+    });
+    Ok(())
+}
+
+/// Hands a message generated from session `session` to the transport and settles it.
+async fn send_generated(
+    state: &AppState,
+    peer: &str,
+    peer_state_mutex: &tokio::sync::Mutex<PeerState>,
+    session: u64,
+    encoded: transport::EncodedMessage,
+) -> Result<()> {
     // No state locks are held across the send.
     match state.transport.send_encoded(&encoded).await {
         Ok(()) => {