[#1356] engine: Evacuate object from shards concurrently

Signed-off-by: Anton Nikiforov <an.nikiforov@yadro.com>

cmd/frostfs-cli/modules/control/evacuation.go

@@ -21,6 +21,9 @@ const (
 	noProgressFlag = "no-progress"
 	scopeFlag      = "scope"
 
+	containerWorkerCountFlag = "container-worker-count"
+	objectWorkerCountFlag    = "object-worker-count"
+
 	scopeAll     = "all"
 	scopeObjects = "objects"
 	scopeTrees   = "trees"
@@ -64,12 +67,16 @@ func startEvacuateShard(cmd *cobra.Command, _ []string) {
 	pk := key.Get(cmd)
 
 	ignoreErrors, _ := cmd.Flags().GetBool(ignoreErrorsFlag)
+	containerWorkerCount, _ := cmd.Flags().GetUint32(containerWorkerCountFlag)
+	objectWorkerCount, _ := cmd.Flags().GetUint32(objectWorkerCountFlag)
 
 	req := &control.StartShardEvacuationRequest{
 		Body: &control.StartShardEvacuationRequest_Body{
 			Shard_ID:             getShardIDList(cmd),
 			IgnoreErrors:         ignoreErrors,
 			Scope:                getEvacuationScope(cmd),
+			ContainerWorkerCount: containerWorkerCount,
+			ObjectWorkerCount:    objectWorkerCount,
 		},
 	}
 
@@ -371,6 +378,8 @@ func initControlStartEvacuationShardCmd() {
 	flags.String(scopeFlag, scopeAll, fmt.Sprintf("Evacuation scope; possible values: %s, %s, %s", scopeTrees, scopeObjects, scopeAll))
 	flags.Bool(awaitFlag, false, "Block execution until evacuation is completed")
 	flags.Bool(noProgressFlag, false, fmt.Sprintf("Print progress if %s provided", awaitFlag))
+	flags.Uint32(containerWorkerCountFlag, 0, "Count of concurrent container evacuation workers")
+	flags.Uint32(objectWorkerCountFlag, 0, "Count of concurrent object evacuation workers")
 
 	startEvacuationShardCmd.MarkFlagsMutuallyExclusive(shardIDFlag, shardAllFlag)
 }

pkg/local_object_storage/engine/evacuate.go

@@ -10,7 +10,6 @@ import (
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
-	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/pilorama"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/util/logicerr"
@@ -24,6 +23,16 @@ import (
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
 	"go.uber.org/zap"
+	"golang.org/x/sync/errgroup"
+)
+
+const (
+	// containerWorkerCountDefault is a default value of the count of
+	// concurrent container evacuation workers.
+	containerWorkerCountDefault = 10
+	// objectWorkerCountDefault is a default value of the count of
+	// concurrent object evacuation workers.
+	objectWorkerCountDefault = 10
 )
 
 var (
@@ -79,6 +88,9 @@ type EvacuateShardPrm struct {
 	IgnoreErrors   bool
 	Async          bool
 	Scope          EvacuateScope
+
+	ContainerWorkerCount uint32
+	ObjectWorkerCount    uint32
 }
 
 // EvacuateShardRes represents result of the EvacuateShard operation.
@@ -189,8 +201,6 @@ func (p *EvacuateShardRes) DeepCopy() *EvacuateShardRes {
 	return res
 }
 
-const defaultEvacuateBatchSize = 100
-
 type pooledShard struct {
 	hashedShard
 	pool util.WorkerPool
@@ -242,8 +252,16 @@ func (e *StorageEngine) Evacuate(ctx context.Context, prm EvacuateShardPrm) (*Ev
 		return nil, err
 	}
 
+	var mtx sync.RWMutex
+	copyShards := func() []pooledShard {
+		mtx.RLock()
+		defer mtx.RUnlock()
+		t := make([]pooledShard, len(shards))
+		copy(t, shards)
+		return t
+	}
 	eg.Go(func() error {
-		return e.evacuateShards(egCtx, shardIDs, prm, res, shards, shardsToEvacuate)
+		return e.evacuateShards(egCtx, shardIDs, prm, res, copyShards, shardsToEvacuate)
 	})
 
 	if prm.Async {
@@ -261,7 +279,7 @@ func ctxOrBackground(ctx context.Context, background bool) context.Context {
 }
 
 func (e *StorageEngine) evacuateShards(ctx context.Context, shardIDs []string, prm EvacuateShardPrm, res *EvacuateShardRes,
-	shards []pooledShard, shardsToEvacuate map[string]*shard.Shard,
+	shards func() []pooledShard, shardsToEvacuate map[string]*shard.Shard,
 ) error {
 	var err error
 	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.evacuateShards",
@@ -287,13 +305,39 @@ func (e *StorageEngine) evacuateShards(ctx context.Context, shardIDs []string, p
 		return err
 	}
 
-	for _, shardID := range shardIDs {
+	ctx, cancel, egShard, egContainer, egObject := e.createErrorGroupsForEvacuation(ctx, prm)
-		if err = e.evacuateShard(ctx, shardID, prm, res, shards, shardsToEvacuate); err != nil {
+	continueLoop := true
+	for i := 0; continueLoop && i < len(shardIDs); i++ {
+		select {
+		case <-ctx.Done():
+			continueLoop = false
+		default:
+			egShard.Go(func() error {
+				err := e.evacuateShard(ctx, cancel, shardIDs[i], prm, res, shards, shardsToEvacuate, egContainer, egObject)
+				if err != nil {
+					cancel(err)
+				}
+				return err
+			})
+		}
+	}
+	err = egShard.Wait()
+	if err != nil {
+		err = fmt.Errorf("shard error: %w", err)
+	}
+	errContainer := egContainer.Wait()
+	errObject := egObject.Wait()
+	if errContainer != nil {
+		err = errors.Join(err, fmt.Errorf("container error: %w", errContainer))
+	}
+	if errObject != nil {
+		err = errors.Join(err, fmt.Errorf("object error: %w", errObject))
+	}
+	if err != nil {
 		e.log.Error(logs.EngineFinishedWithErrorShardsEvacuation, zap.Error(err), zap.Strings("shard_ids", shardIDs), evacuationOperationLogField,
 			zap.String("trace_id", tracingPkg.GetTraceID(ctx)), zap.Stringer("scope", prm.Scope))
 		return err
 	}
-	}
 
 	e.log.Info(logs.EngineFinishedSuccessfullyShardsEvacuation,
 		zap.Strings("shard_ids", shardIDs),
@@ -309,6 +353,27 @@ func (e *StorageEngine) evacuateShards(ctx context.Context, shardIDs []string, p
 	return nil
 }
 
+func (e *StorageEngine) createErrorGroupsForEvacuation(ctx context.Context, prm EvacuateShardPrm) (
+	context.Context, context.CancelCauseFunc, *errgroup.Group, *errgroup.Group, *errgroup.Group,
+) {
+	operationCtx, cancel := context.WithCancelCause(ctx)
+	egObject, _ := errgroup.WithContext(operationCtx)
+	objectWorkerCount := prm.ObjectWorkerCount
+	if objectWorkerCount == 0 {
+		objectWorkerCount = objectWorkerCountDefault
+	}
+	egObject.SetLimit(int(objectWorkerCount))
+	egContainer, _ := errgroup.WithContext(operationCtx)
+	containerWorkerCount := prm.ContainerWorkerCount
+	if containerWorkerCount == 0 {
+		containerWorkerCount = containerWorkerCountDefault
+	}
+	egContainer.SetLimit(int(containerWorkerCount))
+	egShard, _ := errgroup.WithContext(operationCtx)
+
+	return operationCtx, cancel, egShard, egContainer, egObject
+}
+
 func (e *StorageEngine) getTotals(ctx context.Context, prm EvacuateShardPrm, shardsToEvacuate map[string]*shard.Shard, res *EvacuateShardRes) error {
 	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.getTotals")
 	defer span.End()
@@ -335,8 +400,9 @@ func (e *StorageEngine) getTotals(ctx context.Context, prm EvacuateShardPrm, sha
 	return nil
 }
 
-func (e *StorageEngine) evacuateShard(ctx context.Context, shardID string, prm EvacuateShardPrm, res *EvacuateShardRes,
+func (e *StorageEngine) evacuateShard(ctx context.Context, cancel context.CancelCauseFunc, shardID string, prm EvacuateShardPrm, res *EvacuateShardRes,
-	shards []pooledShard, shardsToEvacuate map[string]*shard.Shard,
+	shards func() []pooledShard, shardsToEvacuate map[string]*shard.Shard,
+	egContainer *errgroup.Group, egObject *errgroup.Group,
 ) error {
 	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.evacuateShard",
 		trace.WithAttributes(
@@ -345,11 +411,10 @@ func (e *StorageEngine) evacuateShard(ctx context.Context, shardID string, prm E
 	defer span.End()
 
 	if prm.Scope.WithObjects() {
-		if err := e.evacuateShardObjects(ctx, shardID, prm, res, shards, shardsToEvacuate); err != nil {
+		if err := e.evacuateShardObjects(ctx, cancel, shardID, prm, res, shards, shardsToEvacuate, egContainer, egObject); err != nil {
 			return err
 		}
 	}
-
 	if prm.Scope.WithTrees() && shardsToEvacuate[shardID].PiloramaEnabled() {
 		if err := e.evacuateShardTrees(ctx, shardID, prm, res, shards, shardsToEvacuate); err != nil {
 			return err
@@ -359,44 +424,60 @@ func (e *StorageEngine) evacuateShard(ctx context.Context, shardID string, prm E
 	return nil
 }
 
-func (e *StorageEngine) evacuateShardObjects(ctx context.Context, shardID string, prm EvacuateShardPrm, res *EvacuateShardRes,
+func (e *StorageEngine) evacuateShardObjects(ctx context.Context, cancel context.CancelCauseFunc, shardID string, prm EvacuateShardPrm, res *EvacuateShardRes,
-	shards []pooledShard, shardsToEvacuate map[string]*shard.Shard,
+	shards func() []pooledShard, shardsToEvacuate map[string]*shard.Shard,
+	egContainer *errgroup.Group, egObject *errgroup.Group,
 ) error {
-	var listPrm shard.ListWithCursorPrm
-	listPrm.WithCount(defaultEvacuateBatchSize)
-
 	sh := shardsToEvacuate[shardID]
-	sh.SetEvacuationInProgress(true)
+	var cntPrm shard.IterateOverContainersPrm
-
+	cntPrm.Handler = func(ctx context.Context, name []byte, _ cid.ID) error {
-	var c *meta.Cursor
+		select {
-	for {
+		case <-ctx.Done():
-		listPrm.WithCursor(c)
+			return context.Cause(ctx)
-
+		default:
-		// TODO (@fyrchik): #1731 this approach doesn't work in degraded modes
+		}
-		//  because ListWithCursor works only with the metabase.
+		egContainer.Go(func() error {
-		listRes, err := sh.ListWithCursor(ctx, listPrm)
+			var objPrm shard.IterateOverObjectsInContainerPrm
+			objPrm.BucketName = name
+			objPrm.Handler = func(ctx context.Context, objInfo *object.Info) error {
+				select {
+				case <-ctx.Done():
+					return context.Cause(ctx)
+				default:
+				}
+				egObject.Go(func() error {
+					err := e.evacuateObject(ctx, shardID, objInfo, prm, res, shards, shardsToEvacuate)
 					if err != nil {
-			if errors.Is(err, meta.ErrEndOfListing) || errors.Is(err, shard.ErrDegradedMode) {
+						cancel(err)
-				break
 					}
-			e.log.Error(logs.EngineShardsEvacuationFailedToListObjects, zap.String("shard_id", shardID), zap.Error(err), evacuationOperationLogField,
-				zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
 					return err
+				})
+				return nil
+			}
+			err := sh.IterateOverObjectsInContainer(ctx, objPrm)
+			if err != nil {
+				cancel(err)
 			}
-
-		if err = e.evacuateObjects(ctx, sh, listRes.AddressList(), prm, res, shards, shardsToEvacuate); err != nil {
 			return err
-		}
+		})
-
-		c = listRes.Cursor()
-	}
 		return nil
 	}
 
+	sh.SetEvacuationInProgress(true)
+	err := sh.IterateOverContainers(ctx, cntPrm)
+	if err != nil {
+		cancel(err)
+		e.log.Error(logs.EngineShardsEvacuationFailedToListObjects, zap.String("shard_id", shardID), zap.Error(err), evacuationOperationLogField,
+			zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
+	}
+	return err
+}
+
 func (e *StorageEngine) evacuateShardTrees(ctx context.Context, shardID string, prm EvacuateShardPrm, res *EvacuateShardRes,
-	shards []pooledShard, shardsToEvacuate map[string]*shard.Shard,
+	getShards func() []pooledShard, shardsToEvacuate map[string]*shard.Shard,
 ) error {
 	sh := shardsToEvacuate[shardID]
+	shards := getShards()
 
 	var listPrm pilorama.TreeListTreesPrm
 	first := true
@@ -637,51 +718,49 @@ func (e *StorageEngine) getActualShards(shardIDs []string, prm EvacuateShardPrm)
 	return shards, nil
 }
 
-func (e *StorageEngine) evacuateObjects(ctx context.Context, sh *shard.Shard, toEvacuate []object.Info, prm EvacuateShardPrm, res *EvacuateShardRes,
+func (e *StorageEngine) evacuateObject(ctx context.Context, shardID string, objInfo *object.Info, prm EvacuateShardPrm, res *EvacuateShardRes,
-	shards []pooledShard, shardsToEvacuate map[string]*shard.Shard,
+	getShards func() []pooledShard, shardsToEvacuate map[string]*shard.Shard,
 ) error {
-	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.evacuateObjects",
+	ctx, span := tracing.StartSpanFromContext(ctx, "StorageEngine.evacuateObjects")
-		trace.WithAttributes(
-			attribute.Int("objects_count", len(toEvacuate)),
-		))
 	defer span.End()
 
-	for i := range toEvacuate {
 	select {
 	case <-ctx.Done():
-			return ctx.Err()
+		return context.Cause(ctx)
 	default:
 	}
-		addr := toEvacuate[i].Address
+
+	shards := getShards()
+	addr := objInfo.Address
 
 	var getPrm shard.GetPrm
 	getPrm.SetAddress(addr)
 	getPrm.SkipEvacCheck(true)
 
-		getRes, err := sh.Get(ctx, getPrm)
+	getRes, err := shardsToEvacuate[shardID].Get(ctx, getPrm)
 	if err != nil {
 		if prm.IgnoreErrors {
 			res.objFailed.Add(1)
-				continue
+			return nil
 		}
 		e.log.Error(logs.EngineShardsEvacuationFailedToReadObject, zap.String("address", addr.EncodeToString()), zap.Error(err), evacuationOperationLogField,
 			zap.String("trace_id", tracingPkg.GetTraceID(ctx)))
 		return err
 	}
 
-		evacuatedLocal, err := e.tryEvacuateObjectLocal(ctx, addr, getRes.Object(), sh, shards, shardsToEvacuate, res)
+	evacuatedLocal, err := e.tryEvacuateObjectLocal(ctx, addr, getRes.Object(), shardsToEvacuate[shardID], shards, shardsToEvacuate, res)
 	if err != nil {
 		return err
 	}
 
 	if evacuatedLocal {
-			continue
+		return nil
 	}
 
 	if prm.ObjectsHandler == nil {
 		// Do not check ignoreErrors flag here because
 		// ignoring errors on put make this command kinda useless.
-			return fmt.Errorf("%w: %s", errPutShard, toEvacuate[i])
+		return fmt.Errorf("%w: %s", errPutShard, objInfo)
 	}
 
 	moved, err := prm.ObjectsHandler(ctx, addr, getRes.Object())
@@ -699,7 +778,6 @@ func (e *StorageEngine) evacuateObjects(ctx context.Context, sh *shard.Shard, to
 	} else {
 		return fmt.Errorf("object %s was not replicated", addr)
 	}
-	}
 	return nil
 }
 

pkg/local_object_storage/engine/evacuate_test.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"path/filepath"
 	"strconv"
+	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -174,13 +176,13 @@ func TestEvacuateObjectsNetwork(t *testing.T) {
 	errReplication := errors.New("handler error")
 
 	acceptOneOf := func(objects []*objectSDK.Object, max uint64) func(context.Context, oid.Address, *objectSDK.Object) (bool, error) {
-		var n uint64
+		var n atomic.Uint64
 		return func(_ context.Context, addr oid.Address, obj *objectSDK.Object) (bool, error) {
-			if n == max {
+			if n.Load() == max {
 				return false, errReplication
 			}
 
-			n++
+			n.Add(1)
 			for i := range objects {
 				if addr == objectCore.AddressOf(objects[i]) {
 					require.Equal(t, objects[i], obj)
@@ -314,6 +316,36 @@ func TestEvacuateCancellation(t *testing.T) {
 	require.Equal(t, uint64(0), res.ObjectsEvacuated())
 }
 
+func TestEvacuateCancellationByError(t *testing.T) {
+	t.Parallel()
+	e, ids, _ := newEngineEvacuate(t, 2, 10)
+	defer func() {
+		require.NoError(t, e.Close(context.Background()))
+	}()
+
+	require.NoError(t, e.shards[ids[0].String()].SetMode(mode.ReadOnly))
+	require.NoError(t, e.shards[ids[1].String()].SetMode(mode.ReadOnly))
+
+	var prm EvacuateShardPrm
+	prm.ShardID = ids[1:2]
+	var once atomic.Bool
+	prm.ObjectsHandler = func(ctx context.Context, a oid.Address, o *objectSDK.Object) (bool, error) {
+		var err error
+		flag := true
+		if once.CompareAndSwap(false, true) {
+			err = errors.New("test error")
+			flag = false
+		}
+		return flag, err
+	}
+	prm.Scope = EvacuateScopeObjects
+	prm.ObjectWorkerCount = 2
+	prm.ContainerWorkerCount = 2
+
+	_, err := e.Evacuate(context.Background(), prm)
+	require.ErrorContains(t, err, "test error")
+}
+
 func TestEvacuateSingleProcess(t *testing.T) {
 	e, ids, _ := newEngineEvacuate(t, 2, 3)
 	defer func() {
@@ -531,6 +563,7 @@ func TestEvacuateTreesRemote(t *testing.T) {
 	require.NoError(t, e.shards[ids[0].String()].SetMode(mode.ReadOnly))
 	require.NoError(t, e.shards[ids[1].String()].SetMode(mode.ReadOnly))
 
+	mutex := sync.Mutex{}
 	evacuatedTreeOps := make(map[string][]*pilorama.Move)
 	var prm EvacuateShardPrm
 	prm.ShardID = ids
@@ -545,7 +578,9 @@ func TestEvacuateTreesRemote(t *testing.T) {
 			if op.Time == 0 {
 				return true, "", nil
 			}
+			mutex.Lock()
 			evacuatedTreeOps[key] = append(evacuatedTreeOps[key], &op)
+			mutex.Unlock()
 			height = op.Time + 1
 		}
 	}

pkg/local_object_storage/metabase/list.go

@@ -1,6 +1,7 @@
 package meta
 
 import (
+	"bytes"
 	"context"
 	"time"
 
@@ -61,6 +62,20 @@ func (l ListRes) Cursor() *Cursor {
 	return l.cursor
 }
 
+// IterateOverContainersPrm contains parameters for IterateOverContainers operation.
+type IterateOverContainersPrm struct {
+	// Handler function executed upon containers in db.
+	Handler func(context.Context, []byte, cid.ID) error
+}
+
+// IterateOverObjectsInContainerPrm contains parameters for IterateOverObjectsInContainer operation.
+type IterateOverObjectsInContainerPrm struct {
+	// BucketName container's bucket name.
+	BucketName []byte
+	// Handler function executed upon objects in db.
+	Handler func(context.Context, *objectcore.Info) error
+}
+
 // ListWithCursor lists physical objects available in metabase starting from
 // cursor. Includes objects of all types. Does not include inhumed objects.
 // Use cursor value from response for consecutive requests.
@@ -259,3 +274,155 @@ func parseContainerIDWithPrefix(containerID *cid.ID, name []byte) ([]byte, byte)
 
 	return rawID, name[0]
 }
+
+// IterateOverContainers lists physical containers available in metabase starting from first.
+func (db *DB) IterateOverContainers(ctx context.Context, prm IterateOverContainersPrm) error {
+	var (
+		startedAt = time.Now()
+		success   = false
+	)
+	defer func() {
+		db.metrics.AddMethodDuration("IterateOverContainers", time.Since(startedAt), success)
+	}()
+	_, span := tracing.StartSpanFromContext(ctx, "metabase.IterateOverContainers",
+		trace.WithAttributes(
+			attribute.Bool("has_handler", prm.Handler != nil),
+		))
+	defer span.End()
+
+	db.modeMtx.RLock()
+	defer db.modeMtx.RUnlock()
+
+	if db.mode.NoMetabase() {
+		return ErrDegradedMode
+	}
+
+	err := db.boltDB.View(func(tx *bbolt.Tx) error {
+		return db.iterateOverContainers(ctx, tx, prm)
+	})
+	success = err == nil
+	return metaerr.Wrap(err)
+}
+
+func (db *DB) iterateOverContainers(ctx context.Context, tx *bbolt.Tx, prm IterateOverContainersPrm) error {
+	var containerID cid.ID
+	for _, prefix := range [][]byte{{byte(primaryPrefix)}, {byte(lockersPrefix)}, {byte(tombstonePrefix)}} {
+		c := tx.Cursor()
+		for name, _ := c.Seek(prefix); name != nil && bytes.HasPrefix(name, prefix); name, _ = c.Next() {
+			cidRaw, _ := parseContainerIDWithPrefix(&containerID, name)
+			if cidRaw == nil {
+				continue
+			}
+
+			bktName := make([]byte, len(name))
+			copy(bktName, name)
+			var cnt cid.ID
+			copy(cnt[:], containerID[:])
+			err := prm.Handler(ctx, bktName, cnt)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+// IterateOverObjectsInContainer iterate over physical objects available in metabase starting from first.
+func (db *DB) IterateOverObjectsInContainer(ctx context.Context, prm IterateOverObjectsInContainerPrm) error {
+	var (
+		startedAt = time.Now()
+		success   = false
+	)
+	defer func() {
+		db.metrics.AddMethodDuration("IterateOverObjectsInContainer", time.Since(startedAt), success)
+	}()
+	_, span := tracing.StartSpanFromContext(ctx, "metabase.IterateOverObjectsInContainer",
+		trace.WithAttributes(
+			attribute.Bool("has_handler", prm.Handler != nil),
+		))
+	defer span.End()
+
+	db.modeMtx.RLock()
+	defer db.modeMtx.RUnlock()
+
+	if db.mode.NoMetabase() {
+		return ErrDegradedMode
+	}
+
+	var containerID cid.ID
+	cidRaw, prefix := parseContainerIDWithPrefix(&containerID, prm.BucketName)
+	if cidRaw == nil {
+		return nil
+	}
+	err := db.boltDB.View(func(tx *bbolt.Tx) error {
+		return db.iterateOverObjectsInContainer(ctx, tx, cidRaw, prefix, containerID, prm)
+	})
+	success = err == nil
+	return metaerr.Wrap(err)
+}
+
+func (db *DB) iterateOverObjectsInContainer(ctx context.Context, tx *bbolt.Tx, cidRaw []byte, prefix byte,
+	containerID cid.ID, prm IterateOverObjectsInContainerPrm,
+) error {
+	bkt := tx.Bucket(prm.BucketName)
+	if bkt == nil {
+		return nil
+	}
+	graveyardBkt := tx.Bucket(graveyardBucketName)
+	garbageBkt := tx.Bucket(garbageBucketName)
+	c := bkt.Cursor()
+	k, v := c.First()
+
+	var objType objectSDK.Type
+
+	switch prefix {
+	case primaryPrefix:
+		objType = objectSDK.TypeRegular
+	case lockersPrefix:
+		objType = objectSDK.TypeLock
+	case tombstonePrefix:
+		objType = objectSDK.TypeTombstone
+	default:
+		return nil
+	}
+
+	for ; k != nil; k, v = c.Next() {
+		var obj oid.ID
+		if err := obj.Decode(k); err != nil {
+			break
+		}
+
+		if inGraveyardWithKey(append(cidRaw, k...), graveyardBkt, garbageBkt) > 0 {
+			continue
+		}
+
+		var isLinkingObj bool
+		var ecInfo *objectcore.ECInfo
+		if objType == objectSDK.TypeRegular {
+			var o objectSDK.Object
+			if err := o.Unmarshal(v); err != nil {
+				return err
+			}
+			isLinkingObj = isLinkObject(&o)
+			ecHeader := o.ECHeader()
+			if ecHeader != nil {
+				ecInfo = &objectcore.ECInfo{
+					ParentID: ecHeader.Parent(),
+					Index:    ecHeader.Index(),
+					Total:    ecHeader.Total(),
+				}
+			}
+		}
+
+		var a oid.Address
+		a.SetContainer(containerID)
+		a.SetObject(obj)
+		objInfo := objectcore.Info{Address: a, Type: objType, IsLinkingObject: isLinkingObj, ECInfo: ecInfo}
+		err := prm.Handler(ctx, &objInfo)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}

pkg/local_object_storage/shard/list.go

@@ -34,6 +34,20 @@ func (r ListContainersRes) Containers() []cid.ID {
 	return r.containers
 }
 
+// IterateOverContainersPrm contains parameters for IterateOverContainers operation.
+type IterateOverContainersPrm struct {
+	// Handler function executed upon containers in db.
+	Handler func(context.Context, []byte, cid.ID) error
+}
+
+// IterateOverObjectsInContainerPrm contains parameters for IterateOverObjectsInContainer operation.
+type IterateOverObjectsInContainerPrm struct {
+	// BucketName container's bucket name.
+	BucketName []byte
+	// Handler function executed upon containers in db.
+	Handler func(context.Context, *objectcore.Info) error
+}
+
 // ListWithCursorPrm contains parameters for ListWithCursor operation.
 type ListWithCursorPrm struct {
 	count  uint32
@@ -164,3 +178,54 @@ func (s *Shard) ListWithCursor(ctx context.Context, prm ListWithCursorPrm) (List
 		cursor:   res.Cursor(),
 	}, nil
 }
+
+// IterateOverContainers lists physical containers presented in shard.
+func (s *Shard) IterateOverContainers(ctx context.Context, prm IterateOverContainersPrm) error {
+	_, span := tracing.StartSpanFromContext(ctx, "shard.IterateOverContainers",
+		trace.WithAttributes(
+			attribute.Bool("has_handler", prm.Handler != nil),
+		))
+	defer span.End()
+
+	s.m.RLock()
+	defer s.m.RUnlock()
+
+	if s.info.Mode.NoMetabase() {
+		return ErrDegradedMode
+	}
+
+	var metaPrm meta.IterateOverContainersPrm
+	metaPrm.Handler = prm.Handler
+	err := s.metaBase.IterateOverContainers(ctx, metaPrm)
+	if err != nil {
+		return fmt.Errorf("could not iterate over containers: %w", err)
+	}
+
+	return nil
+}
+
+// IterateOverObjectsInContainer lists physical objects presented in shard for provided container's bucket name.
+func (s *Shard) IterateOverObjectsInContainer(ctx context.Context, prm IterateOverObjectsInContainerPrm) error {
+	_, span := tracing.StartSpanFromContext(ctx, "shard.IterateOverObjectsInContainer",
+		trace.WithAttributes(
+			attribute.Bool("has_handler", prm.Handler != nil),
+		))
+	defer span.End()
+
+	s.m.RLock()
+	defer s.m.RUnlock()
+
+	if s.info.Mode.NoMetabase() {
+		return ErrDegradedMode
+	}
+
+	var metaPrm meta.IterateOverObjectsInContainerPrm
+	metaPrm.BucketName = prm.BucketName
+	metaPrm.Handler = prm.Handler
+	err := s.metaBase.IterateOverObjectsInContainer(ctx, metaPrm)
+	if err != nil {
+		return fmt.Errorf("could not iterate over objects: %w", err)
+	}
+
+	return nil
+}

pkg/services/control/server/evacuate_async.go

@@ -29,6 +29,8 @@ func (s *Server) StartShardEvacuation(ctx context.Context, req *control.StartSha
 		TreeHandler:          s.replicateTree,
 		Async:                true,
 		Scope:                engine.EvacuateScope(req.GetBody().GetScope()),
+		ContainerWorkerCount: req.GetBody().GetContainerWorkerCount(),
+		ObjectWorkerCount:    req.GetBody().GetObjectWorkerCount(),
 	}
 
 	_, err = s.s.Evacuate(ctx, prm)

pkg/services/control/service.proto

@@ -394,6 +394,10 @@ message StartShardEvacuationRequest {
     bool ignore_errors = 2;
     // Evacuation scope.
     uint32 scope = 3;
+    // Count of concurrent container evacuation workers.
+    uint32 container_worker_count = 4;
+    // Count of concurrent object evacuation workers.
+    uint32 object_worker_count = 5;
   }
 
   Body body = 1;