core: add blockProcCount to avoid nested blockProcFeed events

core/blockchain.go

@@ -228,6 +228,7 @@ type BlockChain struct {
 	chainHeadFeed    event.Feed
 	logsFeed         event.Feed
 	blockProcFeed    event.Feed
+	blockProcCounter int32
 	scope            event.SubscriptionScope
 	genesisBlock     *types.Block
 
@@ -1616,8 +1617,15 @@ func (bc *BlockChain) insertChain(chain types.Blocks, setHead bool, makeWitness
 	if bc.insertStopped() {
 		return nil, 0, nil
 	}
+
+	if atomic.AddInt32(&bc.blockProcCounter, 1) == 1 {
 		bc.blockProcFeed.Send(true)
-	defer bc.blockProcFeed.Send(false)
+	}
+	defer func() {
+		if atomic.AddInt32(&bc.blockProcCounter, -1) == 0 {
+			bc.blockProcFeed.Send(false)
+		}
+	}()
 
 	// Start a parallel signature recovery (signer will fluke on fork transition, minimal perf loss)
 	SenderCacher().RecoverFromBlocks(types.MakeSigner(bc.chainConfig, chain[0].Number(), chain[0].Time()), chain)