at max wait for 3 peers to resolve explicit upgrade

lib/replicator.js

@@ -37,6 +37,7 @@ const DEFAULT_MAX_INFLIGHT = [16, 512]
 const SCALE_LATENCY = 50
 const DEFAULT_SEGMENT_SIZE = 256 * 1024 * 8 // 256 KiB in bits
 const NOT_DOWNLOADING_SLACK = 20000 + (Math.random() * 20000) | 0
+const MAX_PEERS_UPGRADE = 3
 
 const PRIORITY = {
   NORMAL: 0,
@@ -1667,12 +1668,15 @@ module.exports = class Replicator {
   // instead its more efficient to only call it when the conditions in here change - ie on sync/add/remove peer
   // Do this when we have more tests.
   _checkUpgradeIfAvailable () {
-    if (this._ifAvailable > 0 || this._upgrade === null || this._upgrade.refs.length === 0) return
+    if (this._ifAvailable > 0 && this.peers.length < MAX_PEERS_UPGRADE) return
+    if (this._upgrade === null || this._upgrade.refs.length === 0) return
     if (this._hadPeers === false && this.findingPeers > 0) return
 
+    const maxPeers = Math.min(this.peers.length, MAX_PEERS_UPGRADE)
+
     // check if a peer can upgrade us
 
-    for (let i = 0; i < this.peers.length; i++) {
+    for (let i = 0; i < maxPeers; i++) {
       const peer = this.peers[i]
 
       if (peer.remoteSynced === false) return
@@ -1699,6 +1703,9 @@ module.exports = class Replicator {
       if (r.inflight.length > 0) return
     }
 
+    // if something is inflight, wait for that first
+    if (this._upgrade.inflight.length > 0) return
+
     // nothing to do, indicate no update avail
 
     const u = this._upgrade