IntermediateRoot: add flag for threshold to update concurrently

Divide the root updating of stateObjects into goroutines if number of stateObjects is at least the threshold
statedb_test.go/TestIntermediateUpdateConcurrently: add test to check if the states after processed with both options are identical

core/state/statedb.go

@@ -21,7 +21,9 @@ import (
 	"errors"
 	"fmt"
 	"math/big"
+	"runtime"
 	"sort"
+	"sync"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -122,6 +124,9 @@ type StateDB struct {
 	StorageUpdated int
 	AccountDeleted int
 	StorageDeleted int
+
+	// Minimum stateObjects (updating accounts) to apply concurrent updates, 0 to disable
+	ConcurrentUpdateThreshold int
 }
 
 // New creates a new state from a given trie.
@@ -855,11 +860,46 @@ func (s *StateDB) IntermediateRoot(deleteEmptyObjects bool) common.Hash {
 	// the account prefetcher. Instead, let's process all the storage updates
 	// first, giving the account prefeches just a few more milliseconds of time
 	// to pull useful data from disk.
+
+	// Get the stateObjects needed to be updated
+	updateObjs := []*stateObject{}
 	for addr := range s.stateObjectsPending {
 		if obj := s.stateObjects[addr]; !obj.deleted {
+			updateObjs = append(updateObjs, obj)
+		}
+	}
+
+	if len(updateObjs) < s.ConcurrentUpdateThreshold || s.ConcurrentUpdateThreshold == 0 {
+		// Update the state objects sequentially
+		for _, obj := range updateObjs {
 			obj.updateRoot(s.db)
 		}
+	} else {
+		// Declare min function
+		min := func(a, b int) int {
+			if a < b {
+				return a
+			}
+			return b
+		}
+		// Update the state objects using goroutines, with maximum of NumCPU goroutines
+		nRoutines := min(runtime.NumCPU(), len(updateObjs))
+		if nRoutines != 0 {
+			nObjPerRoutine := (len(updateObjs) + nRoutines - 1) / nRoutines
+			wg := sync.WaitGroup{}
+			wg.Add(nRoutines)
+			for i := 0; i < len(updateObjs); i += nObjPerRoutine {
+				go func(objs []*stateObject) {
+					defer wg.Done()
+					for _, obj := range objs {
+						obj.updateRoot(s.db)
+					}
+				}(updateObjs[i:min(i+nObjPerRoutine, len(updateObjs))])
+			}
+			wg.Wait()
+		}
 	}
+
 	// Now we're about to start to write changes to the trie. The trie is so far
 	// _untouched_. We can check with the prefetcher, if it can give us a trie
 	// which has the same root, but also has some content loaded into it.

core/state/statedb_test.go

@@ -28,6 +28,7 @@ import (
 	"sync"
 	"testing"
 	"testing/quick"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/rawdb"
@@ -915,3 +916,78 @@ func TestStateDBAccessList(t *testing.T) {
 		t.Fatalf("expected empty, got %d", got)
 	}
 }
+
+func TestIntermediateUpdateConcurrently(t *testing.T) {
+	rng := rand.New(rand.NewSource(time.Now().Unix()))
+	// Create an empty state
+	db1 := rawdb.NewMemoryDatabase()
+	db2 := rawdb.NewMemoryDatabase()
+	state1, _ := New(common.Hash{}, NewDatabase(db1), nil)
+	state2, _ := New(common.Hash{}, NewDatabase(db2), nil)
+
+	// Update it with random data
+	for i := int64(0); i < 1000; i++ {
+		addr := common.BigToAddress(big.NewInt(i))
+		balance := big.NewInt(int64(rng.Int63()))
+		nonce := rng.Uint64()
+		key := common.BigToHash(big.NewInt(int64(rng.Int63())))
+		value := common.BigToHash(big.NewInt(int64(rng.Int63())))
+		code := []byte{byte(rng.Uint64()), byte(rng.Uint64()), byte(rng.Uint64())}
+		state1.SetBalance(addr, balance)
+		state2.SetBalance(addr, balance)
+		state1.SetNonce(addr, nonce)
+		state2.SetNonce(addr, nonce)
+		state1.SetState(addr, key, value)
+		state2.SetState(addr, key, value)
+		state1.SetCode(addr, code)
+		state2.SetCode(addr, code)
+	}
+
+	state1.ConcurrentUpdateThreshold = 0
+	state2.ConcurrentUpdateThreshold = 1
+
+	state1.IntermediateRoot(false) // sequential
+	state2.IntermediateRoot(false) // concurrent
+
+	root1, err1 := state1.Commit(false)
+	root2, err2 := state2.Commit(false)
+
+	if err1 != nil {
+		t.Fatalf("sequential commit failed: %v", err1)
+	}
+	if err1 = state1.Database().TrieDB().Commit(root1, false, nil); err1 != nil {
+		t.Errorf("cannot commit trie %v to persistent database", root1.Hex())
+	}
+	if err2 != nil {
+		t.Fatalf("concurrent commit failed: %v", err2)
+	}
+	if err2 = state2.Database().TrieDB().Commit(root2, false, nil); err2 != nil {
+		t.Errorf("cannot commit trie %v to persistent database", root2.Hex())
+	}
+
+	it1 := db1.NewIterator(nil, nil)
+	it2 := db2.NewIterator(nil, nil)
+	for it1.Next() {
+		if !it2.Next() {
+			t.Fatalf("concurrent iterator ended prematurely")
+		}
+		if !bytes.Equal(it1.Key(), it2.Key()) {
+			t.Fatalf("concurrent iterator key mismatch: " + string(it1.Key()) + " != " + string(it2.Key()))
+		}
+		if !bytes.Equal(it1.Value(), it2.Value()) {
+			t.Fatalf("concurrent iterator value mismatch: " + string(it1.Value()) + " != " + string(it2.Value()))
+		}
+	}
+	if it1.Error() != nil {
+		t.Fatalf("sequential iterator error: %v", it1.Error())
+	}
+	if it2.Error() != nil {
+		t.Fatalf("concurrent iterator error: %v", it2.Error())
+	}
+	if it1.Next() {
+		t.Fatalf("sequential iterator has extra data")
+	}
+	if it2.Next() {
+		t.Fatalf("concurrent iterator has extra data")
+	}
+}