From c672f59ab8a2b80f0fd84dd9c22897f0a7324075 Mon Sep 17 00:00:00 2001
From: Dmitrii Stepanov <d.stepanov@yadro.com>
Date: Wed, 30 Aug 2023 23:36:48 +0300
Subject: [PATCH] [#536] blobovnicza: Drop cache

Each blobovnicza instance is opened
while is in use.

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>
---
 internal/logs/logs.go                         |   1 +
 .../blobovnicza/blobovnicza_test.go           |   5 +-
 pkg/local_object_storage/blobovnicza/put.go   |   8 -
 pkg/local_object_storage/blobovnicza/sizes.go |   2 +-
 .../blobstor/blobovniczatree/active.go        | 213 +++++++++++++++
 .../blobstor/blobovniczatree/blobovnicza.go   | 143 +----------
 .../blobovniczatree/concurrency_test.go       |  59 +++++
 .../blobstor/blobovniczatree/control.go       | 111 ++------
 .../blobstor/blobovniczatree/delete.go        |  67 +----
 .../blobstor/blobovniczatree/errors.go        |   2 +
 .../blobstor/blobovniczatree/exists.go        |  14 +-
 .../blobstor/blobovniczatree/get.go           |  67 +----
 .../blobstor/blobovniczatree/get_range.go     |  76 +-----
 .../blobstor/blobovniczatree/iterate.go       |   4 +-
 .../blobstor/blobovniczatree/manager.go       | 243 ++++++++++++++++++
 .../blobstor/blobovniczatree/put.go           |  45 +---
 16 files changed, 586 insertions(+), 474 deletions(-)
 create mode 100644 pkg/local_object_storage/blobstor/blobovniczatree/active.go
 create mode 100644 pkg/local_object_storage/blobstor/blobovniczatree/concurrency_test.go
 create mode 100644 pkg/local_object_storage/blobstor/blobovniczatree/manager.go

diff --git a/internal/logs/logs.go b/internal/logs/logs.go
index 6ceee4f17..ed88e615b 100644
--- a/internal/logs/logs.go
+++ b/internal/logs/logs.go
@@ -509,4 +509,5 @@ const (
 	RuntimeSoftMemoryLimitUpdated                                           = "soft runtime memory limit value updated"
 	RuntimeSoftMemoryDefinedWithGOMEMLIMIT                                  = "soft runtime memory defined with GOMEMLIMIT environment variable, config value skipped"
 	FailedToCountWritecacheItems                                            = "failed to count writecache items"
+	AttemtToCloseAlreadyClosedBlobovnicza                                   = "attempt to close an already closed blobovnicza"
 )
diff --git a/pkg/local_object_storage/blobovnicza/blobovnicza_test.go b/pkg/local_object_storage/blobovnicza/blobovnicza_test.go
index 48a189c9d..8d701ae5c 100644
--- a/pkg/local_object_storage/blobovnicza/blobovnicza_test.go
+++ b/pkg/local_object_storage/blobovnicza/blobovnicza_test.go
@@ -3,7 +3,6 @@ package blobovnicza
 import (
 	"context"
 	"crypto/rand"
-	"errors"
 	"os"
 	"testing"
 
@@ -98,9 +97,9 @@ func TestBlobovnicza(t *testing.T) {
 		testPutGet(t, blz, oidtest.Address(), objSizeLim, nil, nil)
 	}
 
-	// from now objects should not be saved
+	// blobovnizca accepts object event if full
 	testPutGet(t, blz, oidtest.Address(), 1024, func(err error) bool {
-		return errors.Is(err, ErrFull)
+		return err == nil
 	}, nil)
 
 	require.NoError(t, blz.Close())
diff --git a/pkg/local_object_storage/blobovnicza/put.go b/pkg/local_object_storage/blobovnicza/put.go
index e43b89ec6..787372211 100644
--- a/pkg/local_object_storage/blobovnicza/put.go
+++ b/pkg/local_object_storage/blobovnicza/put.go
@@ -23,10 +23,6 @@ type PutPrm struct {
 type PutRes struct {
 }
 
-// ErrFull is returned when trying to save an
-// object to a filled blobovnicza.
-var ErrFull = logicerr.New("blobovnicza is full")
-
 // SetAddress sets the address of the saving object.
 func (p *PutPrm) SetAddress(addr oid.Address) {
 	p.addr = addr
@@ -65,10 +61,6 @@ func (b *Blobovnicza) Put(ctx context.Context, prm PutPrm) (PutRes, error) {
 	key := addressKey(prm.addr)
 
 	err := b.boltDB.Batch(func(tx *bbolt.Tx) error {
-		if b.full() {
-			return ErrFull
-		}
-
 		buck := tx.Bucket(bucketName)
 		if buck == nil {
 			// expected to happen:
diff --git a/pkg/local_object_storage/blobovnicza/sizes.go b/pkg/local_object_storage/blobovnicza/sizes.go
index 290df9c93..cd1f69725 100644
--- a/pkg/local_object_storage/blobovnicza/sizes.go
+++ b/pkg/local_object_storage/blobovnicza/sizes.go
@@ -55,6 +55,6 @@ func (b *Blobovnicza) itemDeleted(itemSize uint64) {
 	b.metrics.SubOpenBlobovniczaItems(1)
 }
 
-func (b *Blobovnicza) full() bool {
+func (b *Blobovnicza) IsFull() bool {
 	return b.dataSize.Load() >= b.fullSizeLimit
 }
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/active.go b/pkg/local_object_storage/blobstor/blobovniczatree/active.go
new file mode 100644
index 000000000..526699b45
--- /dev/null
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/active.go
@@ -0,0 +1,213 @@
+package blobovniczatree
+
+import (
+	"path/filepath"
+	"sync"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobovnicza"
+	utilSync "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/sync"
+)
+
+type activeDB struct {
+	blz  *blobovnicza.Blobovnicza
+	shDB *sharedDB
+}
+
+func (db *activeDB) Blobovnicza() *blobovnicza.Blobovnicza {
+	return db.blz
+}
+
+func (db *activeDB) Close() {
+	db.shDB.Close()
+}
+
+func (db *activeDB) Path() string {
+	return db.shDB.Path()
+}
+
+// activeDBManager manages active blobovnicza instances (that is, those that are being used for Put).
+//
+// Uses dbManager for opening/closing sharedDB instances.
+// Stores a reference to an open active sharedDB, so dbManager does not close it.
+// When changing the active sharedDB, releases the reference to the previous active sharedDB.
+type activeDBManager struct {
+	levelToActiveDBGuard *sync.RWMutex
+	levelToActiveDB      map[string]*sharedDB
+	levelLock            *utilSync.KeyLocker[string]
+	closed               bool
+
+	dbManager *dbManager
+	leafWidth uint64
+}
+
+func newActiveDBManager(dbManager *dbManager, leafWidth uint64) *activeDBManager {
+	return &activeDBManager{
+		levelToActiveDBGuard: &sync.RWMutex{},
+		levelToActiveDB:      make(map[string]*sharedDB),
+		levelLock:            utilSync.NewKeyLocker[string](),
+
+		dbManager: dbManager,
+		leafWidth: leafWidth,
+	}
+}
+
+// GetOpenedActiveDBForLevel returns active DB for level.
+// DB must be closed after use.
+func (m *activeDBManager) GetOpenedActiveDBForLevel(lvlPath string) (*activeDB, error) {
+	activeDB, err := m.getCurrentActiveIfOk(lvlPath)
+	if err != nil {
+		return nil, err
+	}
+	if activeDB != nil {
+		return activeDB, nil
+	}
+
+	return m.updateAndGetActive(lvlPath)
+}
+
+func (m *activeDBManager) Open() {
+	m.levelToActiveDBGuard.Lock()
+	defer m.levelToActiveDBGuard.Unlock()
+
+	m.closed = false
+}
+
+func (m *activeDBManager) Close() {
+	m.levelToActiveDBGuard.Lock()
+	defer m.levelToActiveDBGuard.Unlock()
+
+	for _, db := range m.levelToActiveDB {
+		db.Close()
+	}
+	m.levelToActiveDB = make(map[string]*sharedDB)
+	m.closed = true
+}
+
+func (m *activeDBManager) getCurrentActiveIfOk(lvlPath string) (*activeDB, error) {
+	m.levelToActiveDBGuard.RLock()
+	defer m.levelToActiveDBGuard.RUnlock()
+
+	if m.closed {
+		return nil, errClosed
+	}
+
+	db, ok := m.levelToActiveDB[lvlPath]
+	if !ok {
+		return nil, nil
+	}
+
+	blz, err := db.Open() //open db for usage, will be closed on activeDB.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	if blz.IsFull() {
+		db.Close()
+		return nil, nil
+	}
+
+	return &activeDB{
+		blz:  blz,
+		shDB: db,
+	}, nil
+}
+
+func (m *activeDBManager) updateAndGetActive(lvlPath string) (*activeDB, error) {
+	m.levelLock.Lock(lvlPath)
+	defer m.levelLock.Unlock(lvlPath)
+
+	current, err := m.getCurrentActiveIfOk(lvlPath)
+	if err != nil {
+		return nil, err
+	}
+	if current != nil {
+		return current, nil
+	}
+
+	nextShDB, err := m.getNextSharedDB(lvlPath)
+	if err != nil {
+		return nil, err
+	}
+
+	if nextShDB == nil {
+		return nil, nil
+	}
+
+	blz, err := nextShDB.Open() // open db for client, client must call Close() after usage
+	if err != nil {
+		return nil, err
+	}
+	return &activeDB{
+		blz:  blz,
+		shDB: nextShDB,
+	}, nil
+}
+
+func (m *activeDBManager) getNextSharedDB(lvlPath string) (*sharedDB, error) {
+	var idx uint64
+	var iterCount uint64
+	hasActive, currentIdx := m.hasActiveDB(lvlPath)
+	if hasActive {
+		idx = (currentIdx + 1) % m.leafWidth
+	}
+
+	var next *sharedDB
+
+	for iterCount < m.leafWidth {
+		path := filepath.Join(lvlPath, u64ToHexString(idx))
+		shDB := m.dbManager.GetByPath(path)
+		db, err := shDB.Open() //open db to hold active DB open, will be closed if db is full, after m.replace or by activeDBManager.Close()
+		if err != nil {
+			return nil, err
+		}
+		if db.IsFull() {
+			shDB.Close()
+		} else {
+			next = shDB
+			break
+		}
+		idx = (idx + 1) % m.leafWidth
+		iterCount++
+	}
+
+	previous, updated := m.replace(lvlPath, next)
+	if !updated && next != nil {
+		next.Close() // manager is closed, so don't hold active DB open
+	}
+	if updated && previous != nil {
+		previous.Close()
+	}
+	return next, nil
+}
+
+func (m *activeDBManager) hasActiveDB(lvlPath string) (bool, uint64) {
+	m.levelToActiveDBGuard.RLock()
+	defer m.levelToActiveDBGuard.RUnlock()
+
+	if m.closed {
+		return false, 0
+	}
+
+	db, ok := m.levelToActiveDB[lvlPath]
+	if !ok {
+		return false, 0
+	}
+	return true, u64FromHexString(filepath.Base(db.Path()))
+}
+
+func (m *activeDBManager) replace(lvlPath string, shDB *sharedDB) (*sharedDB, bool) {
+	m.levelToActiveDBGuard.Lock()
+	defer m.levelToActiveDBGuard.Unlock()
+
+	if m.closed {
+		return nil, false
+	}
+
+	previous := m.levelToActiveDB[lvlPath]
+	if shDB == nil {
+		delete(m.levelToActiveDB, lvlPath)
+	} else {
+		m.levelToActiveDB[lvlPath] = shDB
+	}
+	return previous, true
+}
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/blobovnicza.go b/pkg/local_object_storage/blobstor/blobovniczatree/blobovnicza.go
index 80d064c80..46a8df685 100644
--- a/pkg/local_object_storage/blobstor/blobovniczatree/blobovnicza.go
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/blobovnicza.go
@@ -3,19 +3,12 @@ package blobovniczatree
 import (
 	"errors"
 	"fmt"
-	"path/filepath"
 	"strconv"
-	"sync"
 
-	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
-	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobovnicza"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/compression"
-	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/util/logicerr"
 	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
 	"git.frostfs.info/TrueCloudLab/hrw"
-	"github.com/hashicorp/golang-lru/v2/simplelru"
-	"go.uber.org/zap"
 )
 
 // Blobovniczas represents the storage of the "small" objects.
@@ -61,28 +54,8 @@ import (
 type Blobovniczas struct {
 	cfg
 
-	// cache of opened filled Blobovniczas
-	opened *simplelru.LRU[string, *blobovnicza.Blobovnicza]
-	// lruMtx protects opened cache.
-	// It isn't RWMutex because `Get` calls must
-	// lock this mutex on write, as LRU info is updated.
-	// It must be taken after activeMtx in case when eviction is possible
-	// i.e. `Add`, `Purge` and `Remove` calls.
-	lruMtx sync.Mutex
-
-	// mutex to exclude parallel bbolt.Open() calls
-	// bbolt.Open() deadlocks if it tries to open already opened file
-	openMtx sync.Mutex
-
-	// list of active (opened, non-filled) Blobovniczas
-	activeMtx sync.RWMutex
-	active    map[string]blobovniczaWithIndex
-}
-
-type blobovniczaWithIndex struct {
-	ind uint64
-
-	blz *blobovnicza.Blobovnicza
+	commondbManager *dbManager
+	activeDBManager *activeDBManager
 }
 
 var _ common.Storage = (*Blobovniczas)(nil)
@@ -102,120 +75,12 @@ func NewBlobovniczaTree(opts ...Option) (blz *Blobovniczas) {
 		blz.blzLeafWidth = blz.blzShallowWidth
 	}
 
-	cache, err := simplelru.NewLRU[string, *blobovnicza.Blobovnicza](blz.openedCacheSize, func(p string, value *blobovnicza.Blobovnicza) {
-		lvlPath := filepath.Dir(p)
-		if b, ok := blz.active[lvlPath]; ok && b.ind == u64FromHexString(filepath.Base(p)) {
-			// This branch is taken if we have recently updated active blobovnicza and remove
-			// it from opened cache.
-			return
-		} else if err := value.Close(); err != nil {
-			blz.log.Error(logs.BlobovniczatreeCouldNotCloseBlobovnicza,
-				zap.String("id", p),
-				zap.String("error", err.Error()),
-			)
-		} else {
-			blz.log.Debug(logs.BlobovniczatreeBlobovniczaSuccessfullyClosedOnEvict,
-				zap.String("id", p),
-			)
-		}
-	})
-	if err != nil {
-		// occurs only if the size is not positive
-		panic(fmt.Errorf("could not create LRU cache of size %d: %w", blz.openedCacheSize, err))
-	}
-
-	activeMapCapacity := uint64(1)
-	for i := uint64(0); i < blz.blzShallowDepth; i++ {
-		if i+1 == blz.blzShallowDepth {
-			activeMapCapacity *= blz.blzLeafWidth
-		} else {
-			activeMapCapacity *= blz.blzShallowWidth
-		}
-	}
-
-	blz.opened = cache
-	blz.active = make(map[string]blobovniczaWithIndex, activeMapCapacity)
+	blz.commondbManager = newDBManager(blz.rootPath, blz.blzOpts, blz.blzLeafWidth, blz.readOnly, blz.metrics.Blobovnicza(), blz.log)
+	blz.activeDBManager = newActiveDBManager(blz.commondbManager, blz.blzLeafWidth)
 
 	return blz
 }
 
-// activates and returns activated blobovnicza of p-level (dir).
-//
-// returns error if blobvnicza could not be activated.
-func (b *Blobovniczas) getActivated(lvlPath string) (blobovniczaWithIndex, error) {
-	return b.updateAndGet(lvlPath, nil)
-}
-
-// updates active blobovnicza of p-level (dir).
-//
-// if current active blobovnicza's index is not old, it remains unchanged.
-func (b *Blobovniczas) updateActive(lvlPath string, old *uint64) error {
-	b.log.Debug(logs.BlobovniczatreeUpdatingActiveBlobovnicza, zap.String("path", lvlPath))
-
-	_, err := b.updateAndGet(lvlPath, old)
-
-	b.log.Debug(logs.BlobovniczatreeActiveBlobovniczaSuccessfullyUpdated, zap.String("path", lvlPath))
-
-	return err
-}
-
-// updates and returns active blobovnicza of p-level (dir).
-//
-// if current active blobovnicza's index is not old, it is returned unchanged.
-func (b *Blobovniczas) updateAndGet(lvlPath string, old *uint64) (blobovniczaWithIndex, error) {
-	b.activeMtx.RLock()
-	active, ok := b.active[lvlPath]
-	b.activeMtx.RUnlock()
-
-	if ok {
-		if old != nil {
-			if active.ind == b.blzLeafWidth-1 {
-				return active, logicerr.New("no more Blobovniczas")
-			} else if active.ind != *old {
-				// sort of CAS in order to control concurrent
-				// updateActive calls
-				return active, nil
-			}
-		} else {
-			return active, nil
-		}
-
-		active.ind++
-	}
-
-	var err error
-	if active.blz, err = b.openBlobovnicza(filepath.Join(lvlPath, u64ToHexString(active.ind))); err != nil {
-		return active, err
-	}
-
-	b.activeMtx.Lock()
-	defer b.activeMtx.Unlock()
-
-	// check 2nd time to find out if it blobovnicza was activated while thread was locked
-	tryActive, ok := b.active[lvlPath]
-	if ok && tryActive.blz == active.blz {
-		return tryActive, nil
-	}
-
-	// Remove from opened cache (active blobovnicza should always be opened).
-	// Because `onEvict` callback is called in `Remove`, we need to update
-	// active map beforehand.
-	b.active[lvlPath] = active
-
-	activePath := filepath.Join(lvlPath, u64ToHexString(active.ind))
-	b.lruMtx.Lock()
-	b.opened.Remove(activePath)
-	if ok {
-		b.opened.Add(filepath.Join(lvlPath, u64ToHexString(tryActive.ind)), tryActive.blz)
-	}
-	b.lruMtx.Unlock()
-
-	b.log.Debug(logs.BlobovniczatreeBlobovniczaSuccessfullyActivated,
-		zap.String("path", activePath))
-
-	return active, nil
-}
-
 // returns hash of the object address.
 func addressHash(addr *oid.Address, path string) uint64 {
 	var a string
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/concurrency_test.go b/pkg/local_object_storage/blobstor/blobovniczatree/concurrency_test.go
new file mode 100644
index 000000000..018ecce3c
--- /dev/null
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/concurrency_test.go
@@ -0,0 +1,59 @@
+package blobovniczatree
+
+import (
+	"context"
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/testutil"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger/test"
+	"github.com/stretchr/testify/require"
+)
+
+func TestBlobovniczaTree_Concurrency(t *testing.T) {
+	t.Parallel()
+	const n = 1000
+
+	st := NewBlobovniczaTree(
+		WithLogger(test.NewLogger(t, true)),
+		WithObjectSizeLimit(1024),
+		WithBlobovniczaShallowWidth(10),
+		WithBlobovniczaShallowDepth(1),
+		WithRootPath(t.TempDir()))
+	require.NoError(t, st.Open(false))
+	require.NoError(t, st.Init())
+	t.Cleanup(func() {
+		require.NoError(t, st.Close())
+	})
+
+	objGen := &testutil.SeqObjGenerator{ObjSize: 1}
+
+	var cnt atomic.Int64
+	var wg sync.WaitGroup
+	for i := 0; i < 1000; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for cnt.Add(1) <= n {
+				obj := objGen.Next()
+				addr := testutil.AddressFromObject(t, obj)
+
+				raw, err := obj.Marshal()
+				require.NoError(t, err)
+
+				_, err = st.Put(context.Background(), common.PutPrm{
+					Address: addr,
+					RawData: raw,
+				})
+				require.NoError(t, err)
+
+				_, err = st.Get(context.Background(), common.GetPrm{Address: addr})
+				require.NoError(t, err) // fails very often, correlated to how many goroutines are started
+			}
+		}()
+	}
+
+	wg.Wait()
+}
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/control.go b/pkg/local_object_storage/blobstor/blobovniczatree/control.go
index d7b0799c1..c3d12088a 100644
--- a/pkg/local_object_storage/blobstor/blobovniczatree/control.go
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/control.go
@@ -2,11 +2,8 @@ package blobovniczatree
 
 import (
 	"context"
-	"fmt"
-	"path/filepath"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
-	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobovnicza"
 	"go.uber.org/zap"
 )
 
@@ -14,6 +11,7 @@ import (
 func (b *Blobovniczas) Open(readOnly bool) error {
 	b.readOnly = readOnly
 	b.metrics.SetMode(readOnly)
+	b.openManagers()
 	return nil
 }
 
@@ -23,59 +21,35 @@ func (b *Blobovniczas) Open(readOnly bool) error {
 func (b *Blobovniczas) Init() error {
 	b.log.Debug(logs.BlobovniczatreeInitializingBlobovniczas)
 
+	b.openManagers()
+
 	if b.readOnly {
 		b.log.Debug(logs.BlobovniczatreeReadonlyModeSkipBlobovniczasInitialization)
 		return nil
 	}
 
 	return b.iterateLeaves(context.TODO(), func(p string) (bool, error) {
-		blz, err := b.openBlobovniczaNoCache(p)
+		shBlz := b.openBlobovniczaNoCache(p)
+		_, err := shBlz.Open()
 		if err != nil {
 			return true, err
 		}
-		defer blz.Close()
-
-		if err := blz.Init(); err != nil {
-			return true, fmt.Errorf("could not initialize blobovnicza structure %s: %w", p, err)
-		}
+		defer shBlz.Close()
 
 		b.log.Debug(logs.BlobovniczatreeBlobovniczaSuccessfullyInitializedClosing, zap.String("id", p))
 		return false, nil
 	})
 }
 
+func (b *Blobovniczas) openManagers() {
+	b.commondbManager.Open() //order important
+	b.activeDBManager.Open()
+}
+
 // Close implements common.Storage.
 func (b *Blobovniczas) Close() error {
-	b.activeMtx.Lock()
-
-	b.lruMtx.Lock()
-
-	for p, v := range b.active {
-		if err := v.blz.Close(); err != nil {
-			b.log.Debug(logs.BlobovniczatreeCouldNotCloseActiveBlobovnicza,
-				zap.String("path", p),
-				zap.String("error", err.Error()),
-			)
-		}
-		b.opened.Remove(p)
-	}
-	for _, k := range b.opened.Keys() {
-		blz, _ := b.opened.Get(k)
-		if err := blz.Close(); err != nil {
-			b.log.Debug(logs.BlobovniczatreeCouldNotCloseActiveBlobovnicza,
-				zap.String("path", k),
-				zap.String("error", err.Error()),
-			)
-		}
-		b.opened.Remove(k)
-	}
-
-	b.active = make(map[string]blobovniczaWithIndex)
-	b.metrics.Close()
-
-	b.lruMtx.Unlock()
-
-	b.activeMtx.Unlock()
+	b.activeDBManager.Close() //order important
+	b.commondbManager.Close()
 
 	return nil
 }
@@ -83,61 +57,10 @@ func (b *Blobovniczas) Close() error {
 // opens and returns blobovnicza with path p.
 //
 // If blobovnicza is already opened and cached, instance from cache is returned w/o changes.
-func (b *Blobovniczas) openBlobovnicza(p string) (*blobovnicza.Blobovnicza, error) {
-	b.lruMtx.Lock()
-	v, ok := b.opened.Get(p)
-	b.lruMtx.Unlock()
-	if ok {
-		// blobovnicza should be opened in cache
-		return v, nil
-	}
-
-	lvlPath := filepath.Dir(p)
-	curIndex := u64FromHexString(filepath.Base(p))
-
-	b.activeMtx.RLock()
-	defer b.activeMtx.RUnlock()
-
-	active, ok := b.active[lvlPath]
-	if ok && active.ind == curIndex {
-		return active.blz, nil
-	}
-
-	b.lruMtx.Lock()
-	defer b.lruMtx.Unlock()
-
-	v, ok = b.opened.Get(p)
-	if ok {
-		return v, nil
-	}
-
-	blz, err := b.openBlobovniczaNoCache(p)
-	if err != nil {
-		return nil, err
-	}
-
-	b.opened.Add(p, blz)
-
-	return blz, nil
+func (b *Blobovniczas) openBlobovnicza(p string) *sharedDB {
+	return b.openBlobovniczaNoCache(p)
 }
 
-func (b *Blobovniczas) openBlobovniczaNoCache(p string) (*blobovnicza.Blobovnicza, error) {
-	b.openMtx.Lock()
-	defer b.openMtx.Unlock()
-
-	path := filepath.Join(b.rootPath, p)
-
-	blz := blobovnicza.New(append(b.blzOpts,
-		blobovnicza.WithReadOnly(b.readOnly),
-		blobovnicza.WithPath(path),
-		blobovnicza.WithMetrics(b.metrics.Blobovnicza()),
-	)...)
-
-	if err := blz.Open(); err != nil {
-		return nil, fmt.Errorf("could not open blobovnicza %s: %w", p, err)
-	}
-	if err := blz.Init(); err != nil {
-		return nil, fmt.Errorf("could not init blobovnicza %s: %w", p, err)
-	}
-	return blz, nil
+func (b *Blobovniczas) openBlobovniczaNoCache(p string) *sharedDB {
+	return b.commondbManager.GetByPath(p)
 }
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/delete.go b/pkg/local_object_storage/blobstor/blobovniczatree/delete.go
index 0698c232d..bc7735e74 100644
--- a/pkg/local_object_storage/blobstor/blobovniczatree/delete.go
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/delete.go
@@ -3,7 +3,6 @@ package blobovniczatree
 import (
 	"context"
 	"encoding/hex"
-	"path/filepath"
 	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
@@ -48,10 +47,12 @@ func (b *Blobovniczas) Delete(ctx context.Context, prm common.DeletePrm) (res co
 
 	if prm.StorageID != nil {
 		id := blobovnicza.NewIDFromBytes(prm.StorageID)
-		blz, err := b.openBlobovnicza(id.String())
+		shBlz := b.openBlobovnicza(id.String())
+		blz, err := shBlz.Open()
 		if err != nil {
 			return res, err
 		}
+		defer shBlz.Close()
 
 		if res, err = b.deleteObject(ctx, blz, bPrm); err == nil {
 			success = true
@@ -59,16 +60,10 @@ func (b *Blobovniczas) Delete(ctx context.Context, prm common.DeletePrm) (res co
 		return res, err
 	}
 
-	activeCache := make(map[string]struct{})
 	objectFound := false
 
 	err = b.iterateSortedLeaves(ctx, &prm.Address, func(p string) (bool, error) {
-		dirPath := filepath.Dir(p)
-
-		// don't process active blobovnicza of the level twice
-		_, ok := activeCache[dirPath]
-
-		res, err = b.deleteObjectFromLevel(ctx, bPrm, p, !ok)
+		res, err = b.deleteObjectFromLevel(ctx, bPrm, p)
 		if err != nil {
 			if !client.IsErrObjectNotFound(err) {
 				b.log.Debug(logs.BlobovniczatreeCouldNotRemoveObjectFromLevel,
@@ -78,8 +73,6 @@ func (b *Blobovniczas) Delete(ctx context.Context, prm common.DeletePrm) (res co
 			}
 		}
 
-		activeCache[dirPath] = struct{}{}
-
 		if err == nil {
 			objectFound = true
 		}
@@ -100,57 +93,13 @@ func (b *Blobovniczas) Delete(ctx context.Context, prm common.DeletePrm) (res co
 // tries to delete object from particular blobovnicza.
 //
 // returns no error if object was removed from some blobovnicza of the same level.
-func (b *Blobovniczas) deleteObjectFromLevel(ctx context.Context, prm blobovnicza.DeletePrm, blzPath string, tryActive bool) (common.DeleteRes, error) {
-	lvlPath := filepath.Dir(blzPath)
-
-	// try to remove from blobovnicza if it is opened
-	b.lruMtx.Lock()
-	v, ok := b.opened.Get(blzPath)
-	b.lruMtx.Unlock()
-	if ok {
-		if res, err := b.deleteObject(ctx, v, prm); err == nil {
-			return res, err
-		} else if !client.IsErrObjectNotFound(err) {
-			b.log.Debug(logs.BlobovniczatreeCouldNotRemoveObjectFromOpenedBlobovnicza,
-				zap.String("path", blzPath),
-				zap.String("error", err.Error()),
-			)
-		}
-	}
-
-	// therefore the object is possibly placed in a lighter blobovnicza
-
-	// next we check in the active level blobobnicza:
-	//  * the active blobovnicza is always opened.
-	b.activeMtx.RLock()
-	active, ok := b.active[lvlPath]
-	b.activeMtx.RUnlock()
-
-	if ok && tryActive {
-		if res, err := b.deleteObject(ctx, active.blz, prm); err == nil {
-			return res, err
-		} else if !client.IsErrObjectNotFound(err) {
-			b.log.Debug(logs.BlobovniczatreeCouldNotRemoveObjectFromActiveBlobovnicza,
-				zap.String("path", blzPath),
-				zap.String("error", err.Error()),
-			)
-		}
-	}
-
-	// then object is possibly placed in closed blobovnicza
-
-	// check if it makes sense to try to open the blob
-	// (Blobovniczas "after" the active one are empty anyway,
-	// and it's pointless to open them).
-	if u64FromHexString(filepath.Base(blzPath)) > active.ind {
-		return common.DeleteRes{}, logicerr.Wrap(new(apistatus.ObjectNotFound))
-	}
-
-	// open blobovnicza (cached inside)
-	blz, err := b.openBlobovnicza(blzPath)
+func (b *Blobovniczas) deleteObjectFromLevel(ctx context.Context, prm blobovnicza.DeletePrm, blzPath string) (common.DeleteRes, error) {
+	shBlz := b.openBlobovnicza(blzPath)
+	blz, err := shBlz.Open()
 	if err != nil {
 		return common.DeleteRes{}, err
 	}
+	defer shBlz.Close()
 
 	return b.deleteObject(ctx, blz, prm)
 }
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/errors.go b/pkg/local_object_storage/blobstor/blobovniczatree/errors.go
index 04247280a..be0fd81c3 100644
--- a/pkg/local_object_storage/blobstor/blobovniczatree/errors.go
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/errors.go
@@ -7,6 +7,8 @@ import (
 	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
 )
 
+var errClosed = logicerr.New("blobvnicza is closed")
+
 func isErrOutOfRange(err error) bool {
 	var target *apistatus.ObjectOutOfRange
 	return errors.As(err, &target)
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/exists.go b/pkg/local_object_storage/blobstor/blobovniczatree/exists.go
index c1964c227..f7a192526 100644
--- a/pkg/local_object_storage/blobstor/blobovniczatree/exists.go
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/exists.go
@@ -3,7 +3,6 @@ package blobovniczatree
 import (
 	"context"
 	"encoding/hex"
-	"path/filepath"
 	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
@@ -37,26 +36,22 @@ func (b *Blobovniczas) Exists(ctx context.Context, prm common.ExistsPrm) (common
 
 	if prm.StorageID != nil {
 		id := blobovnicza.NewIDFromBytes(prm.StorageID)
-		blz, err := b.openBlobovnicza(id.String())
+		shBlz := b.openBlobovnicza(id.String())
+		blz, err := shBlz.Open()
 		if err != nil {
 			return common.ExistsRes{}, err
 		}
+		defer shBlz.Close()
 
 		exists, err := blz.Exists(ctx, prm.Address)
 		return common.ExistsRes{Exists: exists}, err
 	}
 
-	activeCache := make(map[string]struct{})
-
 	var gPrm blobovnicza.GetPrm
 	gPrm.SetAddress(prm.Address)
 
 	err := b.iterateSortedLeaves(ctx, &prm.Address, func(p string) (bool, error) {
-		dirPath := filepath.Dir(p)
-
-		_, ok := activeCache[dirPath]
-
-		_, err := b.getObjectFromLevel(ctx, gPrm, p, !ok)
+		_, err := b.getObjectFromLevel(ctx, gPrm, p)
 		if err != nil {
 			if !client.IsErrObjectNotFound(err) {
 				b.log.Debug(logs.BlobovniczatreeCouldNotGetObjectFromLevel,
@@ -65,7 +60,6 @@ func (b *Blobovniczas) Exists(ctx context.Context, prm common.ExistsPrm) (common
 			}
 		}
 
-		activeCache[dirPath] = struct{}{}
 		found = err == nil
 		return found, nil
 	})
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/get.go b/pkg/local_object_storage/blobstor/blobovniczatree/get.go
index 671d045b9..aca39bf3b 100644
--- a/pkg/local_object_storage/blobstor/blobovniczatree/get.go
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/get.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"encoding/hex"
 	"fmt"
-	"path/filepath"
 	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
@@ -48,10 +47,12 @@ func (b *Blobovniczas) Get(ctx context.Context, prm common.GetPrm) (res common.G
 
 	if prm.StorageID != nil {
 		id := blobovnicza.NewIDFromBytes(prm.StorageID)
-		blz, err := b.openBlobovnicza(id.String())
+		shBlz := b.openBlobovnicza(id.String())
+		blz, err := shBlz.Open()
 		if err != nil {
 			return res, err
 		}
+		defer shBlz.Close()
 
 		res, err = b.getObject(ctx, blz, bPrm)
 		if err == nil {
@@ -61,14 +62,8 @@ func (b *Blobovniczas) Get(ctx context.Context, prm common.GetPrm) (res common.G
 		return res, err
 	}
 
-	activeCache := make(map[string]struct{})
-
 	err = b.iterateSortedLeaves(ctx, &prm.Address, func(p string) (bool, error) {
-		dirPath := filepath.Dir(p)
-
-		_, ok := activeCache[dirPath]
-
-		res, err = b.getObjectFromLevel(ctx, bPrm, p, !ok)
+		res, err = b.getObjectFromLevel(ctx, bPrm, p)
 		if err != nil {
 			if !client.IsErrObjectNotFound(err) {
 				b.log.Debug(logs.BlobovniczatreeCouldNotGetObjectFromLevel,
@@ -78,8 +73,6 @@ func (b *Blobovniczas) Get(ctx context.Context, prm common.GetPrm) (res common.G
 			}
 		}
 
-		activeCache[dirPath] = struct{}{}
-
 		// abort iterator if found, otherwise process all Blobovniczas
 		return err == nil, nil
 	})
@@ -98,58 +91,14 @@ func (b *Blobovniczas) Get(ctx context.Context, prm common.GetPrm) (res common.G
 // tries to read object from particular blobovnicza.
 //
 // returns error if object could not be read from any blobovnicza of the same level.
-func (b *Blobovniczas) getObjectFromLevel(ctx context.Context, prm blobovnicza.GetPrm, blzPath string, tryActive bool) (common.GetRes, error) {
-	lvlPath := filepath.Dir(blzPath)
-
-	// try to read from blobovnicza if it is opened
-	b.lruMtx.Lock()
-	v, ok := b.opened.Get(blzPath)
-	b.lruMtx.Unlock()
-	if ok {
-		if res, err := b.getObject(ctx, v, prm); err == nil {
-			return res, err
-		} else if !client.IsErrObjectNotFound(err) {
-			b.log.Debug(logs.BlobovniczatreeCouldNotReadObjectFromOpenedBlobovnicza,
-				zap.String("path", blzPath),
-				zap.String("error", err.Error()),
-			)
-		}
-	}
-
-	// therefore the object is possibly placed in a lighter blobovnicza
-
-	// next we check in the active level blobobnicza:
-	//  * the freshest objects are probably the most demanded;
-	//  * the active blobovnicza is always opened.
-	b.activeMtx.RLock()
-	active, ok := b.active[lvlPath]
-	b.activeMtx.RUnlock()
-
-	if ok && tryActive {
-		if res, err := b.getObject(ctx, active.blz, prm); err == nil {
-			return res, err
-		} else if !client.IsErrObjectNotFound(err) {
-			b.log.Debug(logs.BlobovniczatreeCouldNotGetObjectFromActiveBlobovnicza,
-				zap.String("path", blzPath),
-				zap.String("error", err.Error()),
-			)
-		}
-	}
-
-	// then object is possibly placed in closed blobovnicza
-
-	// check if it makes sense to try to open the blob
-	// (Blobovniczas "after" the active one are empty anyway,
-	// and it's pointless to open them).
-	if u64FromHexString(filepath.Base(blzPath)) > active.ind {
-		return common.GetRes{}, logicerr.Wrap(new(apistatus.ObjectNotFound))
-	}
-
+func (b *Blobovniczas) getObjectFromLevel(ctx context.Context, prm blobovnicza.GetPrm, blzPath string) (common.GetRes, error) {
 	// open blobovnicza (cached inside)
-	blz, err := b.openBlobovnicza(blzPath)
+	shBlz := b.openBlobovnicza(blzPath)
+	blz, err := shBlz.Open()
 	if err != nil {
 		return common.GetRes{}, err
 	}
+	defer shBlz.Close()
 
 	return b.getObject(ctx, blz, prm)
 }
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/get_range.go b/pkg/local_object_storage/blobstor/blobovniczatree/get_range.go
index 088ebe249..3d1a6b988 100644
--- a/pkg/local_object_storage/blobstor/blobovniczatree/get_range.go
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/get_range.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"encoding/hex"
 	"fmt"
-	"path/filepath"
 	"strconv"
 	"time"
 
@@ -47,10 +46,12 @@ func (b *Blobovniczas) GetRange(ctx context.Context, prm common.GetRangePrm) (re
 
 	if prm.StorageID != nil {
 		id := blobovnicza.NewIDFromBytes(prm.StorageID)
-		blz, err := b.openBlobovnicza(id.String())
+		shBlz := b.openBlobovnicza(id.String())
+		blz, err := shBlz.Open()
 		if err != nil {
 			return common.GetRangeRes{}, err
 		}
+		defer shBlz.Close()
 
 		res, err := b.getObjectRange(ctx, blz, prm)
 		if err == nil {
@@ -60,15 +61,10 @@ func (b *Blobovniczas) GetRange(ctx context.Context, prm common.GetRangePrm) (re
 		return res, err
 	}
 
-	activeCache := make(map[string]struct{})
 	objectFound := false
 
 	err = b.iterateSortedLeaves(ctx, &prm.Address, func(p string) (bool, error) {
-		dirPath := filepath.Dir(p)
-
-		_, ok := activeCache[dirPath]
-
-		res, err = b.getRangeFromLevel(ctx, prm, p, !ok)
+		res, err = b.getRangeFromLevel(ctx, prm, p)
 		if err != nil {
 			outOfBounds := isErrOutOfRange(err)
 			if !outOfBounds && !client.IsErrObjectNotFound(err) {
@@ -82,8 +78,6 @@ func (b *Blobovniczas) GetRange(ctx context.Context, prm common.GetRangePrm) (re
 			}
 		}
 
-		activeCache[dirPath] = struct{}{}
-
 		objectFound = err == nil
 
 		// abort iterator if found, otherwise process all Blobovniczas
@@ -106,68 +100,14 @@ func (b *Blobovniczas) GetRange(ctx context.Context, prm common.GetRangePrm) (re
 // tries to read range of object payload data from particular blobovnicza.
 //
 // returns error if object could not be read from any blobovnicza of the same level.
-func (b *Blobovniczas) getRangeFromLevel(ctx context.Context, prm common.GetRangePrm, blzPath string, tryActive bool) (common.GetRangeRes, error) {
-	lvlPath := filepath.Dir(blzPath)
-
-	// try to read from blobovnicza if it is opened
-	b.lruMtx.Lock()
-	v, ok := b.opened.Get(blzPath)
-	b.lruMtx.Unlock()
-	if ok {
-		res, err := b.getObjectRange(ctx, v, prm)
-		switch {
-		case err == nil,
-			isErrOutOfRange(err):
-			return res, err
-		default:
-			if !client.IsErrObjectNotFound(err) {
-				b.log.Debug(logs.BlobovniczatreeCouldNotReadPayloadRangeFromOpenedBlobovnicza,
-					zap.String("path", blzPath),
-					zap.String("error", err.Error()),
-				)
-			}
-		}
-	}
-
-	// therefore the object is possibly placed in a lighter blobovnicza
-
-	// next we check in the active level blobobnicza:
-	//  * the freshest objects are probably the most demanded;
-	//  * the active blobovnicza is always opened.
-	b.activeMtx.RLock()
-	active, ok := b.active[lvlPath]
-	b.activeMtx.RUnlock()
-
-	if ok && tryActive {
-		res, err := b.getObjectRange(ctx, active.blz, prm)
-		switch {
-		case err == nil,
-			isErrOutOfRange(err):
-			return res, err
-		default:
-			if !client.IsErrObjectNotFound(err) {
-				b.log.Debug(logs.BlobovniczatreeCouldNotReadPayloadRangeFromActiveBlobovnicza,
-					zap.String("path", blzPath),
-					zap.String("error", err.Error()),
-				)
-			}
-		}
-	}
-
-	// then object is possibly placed in closed blobovnicza
-
-	// check if it makes sense to try to open the blob
-	// (Blobovniczas "after" the active one are empty anyway,
-	// and it's pointless to open them).
-	if u64FromHexString(filepath.Base(blzPath)) > active.ind {
-		return common.GetRangeRes{}, logicerr.Wrap(new(apistatus.ObjectNotFound))
-	}
-
+func (b *Blobovniczas) getRangeFromLevel(ctx context.Context, prm common.GetRangePrm, blzPath string) (common.GetRangeRes, error) {
 	// open blobovnicza (cached inside)
-	blz, err := b.openBlobovnicza(blzPath)
+	shBlz := b.openBlobovnicza(blzPath)
+	blz, err := shBlz.Open()
 	if err != nil {
 		return common.GetRangeRes{}, err
 	}
+	defer shBlz.Close()
 
 	return b.getObjectRange(ctx, blz, prm)
 }
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/iterate.go b/pkg/local_object_storage/blobstor/blobovniczatree/iterate.go
index aeac854f7..cc273839a 100644
--- a/pkg/local_object_storage/blobstor/blobovniczatree/iterate.go
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/iterate.go
@@ -68,13 +68,15 @@ func (b *Blobovniczas) Iterate(ctx context.Context, prm common.IteratePrm) (comm
 // iterator over all Blobovniczas in unsorted order. Break on f's error return.
 func (b *Blobovniczas) iterateBlobovniczas(ctx context.Context, ignoreErrors bool, f func(string, *blobovnicza.Blobovnicza) error) error {
 	return b.iterateLeaves(ctx, func(p string) (bool, error) {
-		blz, err := b.openBlobovnicza(p)
+		shBlz := b.openBlobovnicza(p)
+		blz, err := shBlz.Open()
 		if err != nil {
 			if ignoreErrors {
 				return false, nil
 			}
 			return false, fmt.Errorf("could not open blobovnicza %s: %w", p, err)
 		}
+		defer shBlz.Close()
 
 		err = f(p, blz)
 
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/manager.go b/pkg/local_object_storage/blobstor/blobovniczatree/manager.go
new file mode 100644
index 000000000..941d9961d
--- /dev/null
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/manager.go
@@ -0,0 +1,243 @@
+package blobovniczatree
+
+import (
+	"fmt"
+	"path/filepath"
+	"sync"
+	"sync/atomic"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobovnicza"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger"
+	"go.uber.org/zap"
+)
+
+// sharedDB is responsible for opening and closing a file of single blobovnicza.
+type sharedDB struct {
+	guard    *sync.RWMutex
+	blcza    *blobovnicza.Blobovnicza
+	refCount uint32
+
+	openDBCounter *openDBCounter
+	closedFlag    *atomic.Bool
+	options       []blobovnicza.Option
+	path          string
+	readOnly      bool
+	metrics       blobovnicza.Metrics
+	log           *logger.Logger
+}
+
+func newSharedDB(options []blobovnicza.Option, path string, readOnly bool,
+	metrics blobovnicza.Metrics, openDBCounter *openDBCounter, closedFlag *atomic.Bool, log *logger.Logger) *sharedDB {
+	return &sharedDB{
+		guard: &sync.RWMutex{},
+
+		options:       options,
+		path:          path,
+		readOnly:      readOnly,
+		metrics:       metrics,
+		closedFlag:    closedFlag,
+		log:           log,
+		openDBCounter: openDBCounter,
+	}
+}
+
+func (b *sharedDB) Open() (*blobovnicza.Blobovnicza, error) {
+	if b.closedFlag.Load() {
+		return nil, errClosed
+	}
+
+	b.guard.Lock()
+	defer b.guard.Unlock()
+
+	if b.refCount > 0 {
+		b.refCount++
+		return b.blcza, nil
+	}
+
+	blz := blobovnicza.New(append(b.options,
+		blobovnicza.WithReadOnly(b.readOnly),
+		blobovnicza.WithPath(b.path),
+		blobovnicza.WithMetrics(b.metrics),
+	)...)
+
+	if err := blz.Open(); err != nil {
+		return nil, fmt.Errorf("could not open blobovnicza %s: %w", b.path, err)
+	}
+	if err := blz.Init(); err != nil {
+		return nil, fmt.Errorf("could not init blobovnicza %s: %w", b.path, err)
+	}
+
+	b.refCount++
+	b.blcza = blz
+	b.openDBCounter.Inc()
+
+	return blz, nil
+}
+
+func (b *sharedDB) Close() {
+	b.guard.Lock()
+	defer b.guard.Unlock()
+
+	if b.refCount == 0 {
+		b.log.Error(logs.AttemtToCloseAlreadyClosedBlobovnicza, zap.String("id", b.path))
+		return
+	}
+
+	if b.refCount == 1 {
+		b.refCount = 0
+		if err := b.blcza.Close(); err != nil {
+			b.log.Error(logs.BlobovniczatreeCouldNotCloseBlobovnicza,
+				zap.String("id", b.path),
+				zap.String("error", err.Error()),
+			)
+		}
+		b.blcza = nil
+		b.openDBCounter.Dec()
+		return
+	}
+
+	b.refCount--
+}
+
+func (b *sharedDB) Path() string {
+	return b.path
+}
+
+// levelDbManager stores pointers of the sharedDB's for the leaf directory of the blobovnicza tree.
+type levelDbManager struct {
+	databases []*sharedDB
+}
+
+func newLevelDBManager(width uint64, options []blobovnicza.Option, rootPath string, lvlPath string,
+	readOnly bool, metrics blobovnicza.Metrics, openDBCounter *openDBCounter, closedFlog *atomic.Bool, log *logger.Logger) *levelDbManager {
+	result := &levelDbManager{
+		databases: make([]*sharedDB, width),
+	}
+	var idx uint64
+	for idx = 0; idx < width; idx++ {
+		result.databases[idx] = newSharedDB(options, filepath.Join(rootPath, lvlPath, u64ToHexString(idx)), readOnly, metrics, openDBCounter, closedFlog, log)
+	}
+	return result
+}
+
+func (m *levelDbManager) GetByIndex(idx uint64) *sharedDB {
+	return m.databases[idx]
+}
+
+// dbManager manages the opening and closing of blobovnicza instances.
+//
+// The blobovnicza opens at the first request, closes after the last request.
+type dbManager struct {
+	levelToManager      map[string]*levelDbManager
+	levelToManagerGuard *sync.RWMutex
+	closedFlag          *atomic.Bool
+	dbCounter           *openDBCounter
+
+	rootPath  string
+	options   []blobovnicza.Option
+	readOnly  bool
+	metrics   blobovnicza.Metrics
+	leafWidth uint64
+	log       *logger.Logger
+}
+
+func newDBManager(rootPath string, options []blobovnicza.Option, leafWidth uint64, readOnly bool, metrics blobovnicza.Metrics, log *logger.Logger) *dbManager {
+	return &dbManager{
+		rootPath:            rootPath,
+		options:             options,
+		readOnly:            readOnly,
+		metrics:             metrics,
+		leafWidth:           leafWidth,
+		levelToManager:      make(map[string]*levelDbManager),
+		levelToManagerGuard: &sync.RWMutex{},
+		log:                 log,
+		closedFlag:          &atomic.Bool{},
+		dbCounter:           newOpenDBCounter(),
+	}
+}
+
+func (m *dbManager) GetByPath(path string) *sharedDB {
+	lvlPath := filepath.Dir(path)
+	curIndex := u64FromHexString(filepath.Base(path))
+	levelManager := m.getLevelManager(lvlPath)
+	return levelManager.GetByIndex(curIndex)
+}
+
+func (m *dbManager) Open() {
+	m.closedFlag.Store(false)
+}
+
+func (m *dbManager) Close() {
+	m.closedFlag.Store(true)
+	m.dbCounter.WaitUntilAllClosed()
+}
+
+func (m *dbManager) getLevelManager(lvlPath string) *levelDbManager {
+	result := m.getLevelManagerIfExists(lvlPath)
+	if result != nil {
+		return result
+	}
+	return m.getOrCreateLevelManager(lvlPath)
+}
+
+func (m *dbManager) getLevelManagerIfExists(lvlPath string) *levelDbManager {
+	m.levelToManagerGuard.RLock()
+	defer m.levelToManagerGuard.RUnlock()
+
+	return m.levelToManager[lvlPath]
+}
+
+func (m *dbManager) getOrCreateLevelManager(lvlPath string) *levelDbManager {
+	m.levelToManagerGuard.Lock()
+	defer m.levelToManagerGuard.Unlock()
+
+	if result, ok := m.levelToManager[lvlPath]; ok {
+		return result
+	}
+
+	result := newLevelDBManager(m.leafWidth, m.options, m.rootPath, lvlPath, m.readOnly, m.metrics, m.dbCounter, m.closedFlag, m.log)
+	m.levelToManager[lvlPath] = result
+	return result
+}
+
+type openDBCounter struct {
+	cond  *sync.Cond
+	count uint64
+}
+
+func newOpenDBCounter() *openDBCounter {
+	return &openDBCounter{
+		cond: &sync.Cond{
+			L: &sync.Mutex{},
+		},
+	}
+}
+
+func (c *openDBCounter) Inc() {
+	c.cond.L.Lock()
+	defer c.cond.L.Unlock()
+
+	c.count++
+}
+
+func (c *openDBCounter) Dec() {
+	c.cond.L.Lock()
+	defer c.cond.L.Unlock()
+
+	if c.count > 0 {
+		c.count--
+	}
+
+	if c.count == 0 {
+		c.cond.Broadcast()
+	}
+}
+
+func (c *openDBCounter) WaitUntilAllClosed() {
+	c.cond.L.Lock()
+	for c.count > 0 {
+		c.cond.Wait()
+	}
+	c.cond.L.Unlock()
+}
diff --git a/pkg/local_object_storage/blobstor/blobovniczatree/put.go b/pkg/local_object_storage/blobstor/blobovniczatree/put.go
index 038d5244d..aae280e0b 100644
--- a/pkg/local_object_storage/blobstor/blobovniczatree/put.go
+++ b/pkg/local_object_storage/blobstor/blobovniczatree/put.go
@@ -2,7 +2,6 @@ package blobovniczatree
 
 import (
 	"context"
-	"errors"
 	"path/filepath"
 	"time"
 
@@ -10,7 +9,6 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobovnicza"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
 	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
-	"go.etcd.io/bbolt"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
 	"go.uber.org/zap"
@@ -76,8 +74,8 @@ type putIterator struct {
 	PutPrm  blobovnicza.PutPrm
 }
 
-func (i *putIterator) iterate(ctx context.Context, path string) (bool, error) {
-	active, err := i.B.getActivated(path)
+func (i *putIterator) iterate(ctx context.Context, lvlPath string) (bool, error) {
+	active, err := i.B.activeDBManager.GetOpenedActiveDBForLevel(lvlPath)
 	if err != nil {
 		if !isLogical(err) {
 			i.B.reportError(logs.BlobovniczatreeCouldNotGetActiveBlobovnicza, err)
@@ -89,46 +87,29 @@ func (i *putIterator) iterate(ctx context.Context, path string) (bool, error) {
 		return false, nil
 	}
 
-	if _, err := active.blz.Put(ctx, i.PutPrm); err != nil {
-		// Check if blobovnicza is full. We could either receive `blobovnicza.ErrFull` error
-		// or update active blobovnicza in other thread. In the latter case the database will be closed
-		// and `updateActive` takes care of not updating the active blobovnicza twice.
-		if isFull := errors.Is(err, blobovnicza.ErrFull); isFull || errors.Is(err, bbolt.ErrDatabaseNotOpen) {
-			if isFull {
-				i.B.log.Debug(logs.BlobovniczatreeBlobovniczaOverflowed,
-					zap.String("path", filepath.Join(path, u64ToHexString(active.ind))))
-			}
+	if active == nil {
+		i.B.log.Debug(logs.BlobovniczatreeBlobovniczaOverflowed, zap.String("level", lvlPath))
+		return false, nil
+	}
+	defer active.Close()
 
-			if err := i.B.updateActive(path, &active.ind); err != nil {
-				if !isLogical(err) {
-					i.B.reportError(logs.BlobovniczatreeCouldNotUpdateActiveBlobovnicza, err)
-				} else {
-					i.B.log.Debug(logs.BlobovniczatreeCouldNotUpdateActiveBlobovnicza,
-						zap.String("level", path),
-						zap.String("error", err.Error()))
-				}
+	i.AllFull = false
 
-				return false, nil
-			}
-
-			return i.iterate(ctx, path)
-		}
-
-		i.AllFull = false
+	_, err = active.Blobovnicza().Put(ctx, i.PutPrm)
+	if err != nil {
 		if !isLogical(err) {
 			i.B.reportError(logs.BlobovniczatreeCouldNotPutObjectToActiveBlobovnicza, err)
 		} else {
 			i.B.log.Debug(logs.BlobovniczatreeCouldNotPutObjectToActiveBlobovnicza,
-				zap.String("path", filepath.Join(path, u64ToHexString(active.ind))),
+				zap.String("path", active.Path()),
 				zap.String("error", err.Error()))
 		}
 
 		return false, nil
 	}
 
-	path = filepath.Join(path, u64ToHexString(active.ind))
-
-	i.ID = blobovnicza.NewIDFromBytes([]byte(path))
+	idx := u64FromHexString(filepath.Base(active.Path()))
+	i.ID = blobovnicza.NewIDFromBytes([]byte(filepath.Join(lvlPath, u64ToHexString(idx))))
 
 	return true, nil
 }