core: add blockProcCount to avoid nested blockProcFeed events

core/blockchain.go

@@ -222,14 +222,15 @@ type BlockChain struct {
 	statedb       *state.CachingDB                 // State database to reuse between imports (contains state cache)
 	txIndexer     *txIndexer                       // Transaction indexer, might be nil if not enabled
 
-	hc            *HeaderChain
-	rmLogsFeed    event.Feed
-	chainFeed     event.Feed
-	chainHeadFeed event.Feed
-	logsFeed      event.Feed
-	blockProcFeed event.Feed
-	scope         event.SubscriptionScope
-	genesisBlock  *types.Block
+	hc               *HeaderChain
+	rmLogsFeed       event.Feed
+	chainFeed        event.Feed
+	chainHeadFeed    event.Feed
+	logsFeed         event.Feed
+	blockProcFeed    event.Feed
+	blockProcCounter int32
+	scope            event.SubscriptionScope
+	genesisBlock     *types.Block
 
 	// This mutex synchronizes chain write operations.
 	// Readers don't need to take it, they can just read the database.
@@ -1616,8 +1617,15 @@ func (bc *BlockChain) insertChain(chain types.Blocks, setHead bool, makeWitness
 	if bc.insertStopped() {
 		return nil, 0, nil
 	}
-	bc.blockProcFeed.Send(true)
-	defer bc.blockProcFeed.Send(false)
+
+	if atomic.AddInt32(&bc.blockProcCounter, 1) == 1 {
+		bc.blockProcFeed.Send(true)
+	}
+	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)