diff --git a/br/pkg/lightning/backend/local/local.go b/br/pkg/lightning/backend/local/local.go
index 317124d0b8d19..e32606207082e 100644
--- a/br/pkg/lightning/backend/local/local.go
+++ b/br/pkg/lightning/backend/local/local.go
@@ -394,6 +394,13 @@ func openDuplicateDB(storeDir string) (*pebble.DB, error) {
 	return pebble.Open(dbPath, opts)
 }
 
+var (
+	// RunInTest indicates whether the current process is running in test.
+	RunInTest bool
+	// LastAlloc is the last ID allocator.
+	LastAlloc manual.Allocator
+)
+
 // NewLocalBackend creates new connections to tikv.
 func NewLocalBackend(
 	ctx context.Context,
@@ -461,6 +468,11 @@ func NewLocalBackend(
 	} else {
 		writeLimiter = noopStoreWriteLimiter{}
 	}
+	alloc := manual.Allocator{}
+	if RunInTest {
+		alloc.RefCnt = new(atomic.Int64)
+		LastAlloc = alloc
+	}
 	local := &local{
 		engines:  sync.Map{},
 		pdCtl:    pdCtl,
@@ -486,7 +498,7 @@ func NewLocalBackend(
 		keyAdapter:              keyAdapter,
 		errorMgr:                errorMgr,
 		importClientFactory:     importClientFactory,
-		bufferPool:              membuf.NewPool(membuf.WithAllocator(manual.Allocator{})),
+		bufferPool:              membuf.NewPool(membuf.WithAllocator(alloc)),
 		writeLimiter:            writeLimiter,
 		logger:                  log.FromContext(ctx),
 		encBuilder:              NewEncodingBuilder(ctx),
diff --git a/br/pkg/lightning/manual/BUILD.bazel b/br/pkg/lightning/manual/BUILD.bazel
index 6d1fc18dd2495..d54902a23c066 100644
--- a/br/pkg/lightning/manual/BUILD.bazel
+++ b/br/pkg/lightning/manual/BUILD.bazel
@@ -10,4 +10,5 @@ go_library(
     cgo = True,
     importpath = "github.com/pingcap/tidb/br/pkg/lightning/manual",
     visibility = ["//visibility:public"],
+    deps = ["@org_uber_go_atomic//:atomic"],
 )
diff --git a/br/pkg/lightning/manual/allocator.go b/br/pkg/lightning/manual/allocator.go
index 821eb750c5030..18aa8cc9353c4 100644
--- a/br/pkg/lightning/manual/allocator.go
+++ b/br/pkg/lightning/manual/allocator.go
@@ -14,8 +14,33 @@
 
 package manual
 
-type Allocator struct{}
+import (
+	"fmt"
 
-func (Allocator) Alloc(n int) []byte { return New(n) }
+	"go.uber.org/atomic"
+)
 
-func (Allocator) Free(b []byte) { Free(b) }
+type Allocator struct {
+	RefCnt *atomic.Int64
+}
+
+func (a Allocator) Alloc(n int) []byte {
+	if a.RefCnt != nil {
+		a.RefCnt.Add(1)
+	}
+	return New(n)
+}
+
+func (a Allocator) Free(b []byte) {
+	if a.RefCnt != nil {
+		a.RefCnt.Add(-1)
+	}
+	Free(b)
+}
+
+func (a Allocator) CheckRefCnt() error {
+	if a.RefCnt != nil && a.RefCnt.Load() != 0 {
+		return fmt.Errorf("memory leak detected, refCnt: %d", a.RefCnt.Load())
+	}
+	return nil
+}
diff --git a/ddl/ingest/engine.go b/ddl/ingest/engine.go
index d875d78e346d0..5bf32762dcc22 100644
--- a/ddl/ingest/engine.go
+++ b/ddl/ingest/engine.go
@@ -83,6 +83,11 @@ func (ei *engineInfo) Clean() {
 			zap.Int64("job ID", ei.jobID), zap.Int64("index ID", ei.indexID))
 	}
 	ei.openedEngine = nil
+	err = ei.closeWriters()
+	if err != nil {
+		logutil.BgLogger().Error(LitErrCloseWriterErr, zap.Error(err),
+			zap.Int64("job ID", ei.jobID), zap.Int64("index ID", ei.indexID))
+	}
 	// Here the local intermediate files will be removed.
 	err = closedEngine.Cleanup(ei.ctx)
 	if err != nil {
@@ -102,8 +107,14 @@ func (ei *engineInfo) ImportAndClean() error {
 		return errors.New(LitErrCloseEngineErr)
 	}
 	ei.openedEngine = nil
+	err := ei.closeWriters()
+	if err != nil {
+		logutil.BgLogger().Error(LitErrCloseWriterErr, zap.Error(err),
+			zap.Int64("job ID", ei.jobID), zap.Int64("index ID", ei.indexID))
+		return err
+	}
 
-	err := ei.diskRoot.UpdateUsageAndQuota()
+	err = ei.diskRoot.UpdateUsageAndQuota()
 	if err != nil {
 		logutil.BgLogger().Error(LitErrUpdateDiskStats, zap.Error(err),
 			zap.Int64("job ID", ei.jobID), zap.Int64("index ID", ei.indexID))
@@ -182,6 +193,22 @@ func (ei *engineInfo) newWriterContext(workerID int) (*WriterContext, error) {
 	}, nil
 }
 
+func (ei *engineInfo) closeWriters() error {
+	var firstErr error
+	for wid := range ei.writerCache.Keys() {
+		if w, ok := ei.writerCache.Load(wid); ok {
+			_, err := w.Close(ei.ctx)
+			if err != nil {
+				if firstErr == nil {
+					firstErr = err
+				}
+			}
+		}
+		ei.writerCache.Delete(wid)
+	}
+	return firstErr
+}
+
 // WriteRow Write one row into local writer buffer.
 func (wCtx *WriterContext) WriteRow(key, idxVal []byte) error {
 	kvs := make([]common.KvPair, 1)
diff --git a/ddl/ingest/message.go b/ddl/ingest/message.go
index 1a68541d68f0c..ac2a213e81f9f 100644
--- a/ddl/ingest/message.go
+++ b/ddl/ingest/message.go
@@ -57,6 +57,7 @@ const (
 	LitInfoChgMemSetting    string = "[ddl-ingest] change memory setting for lightning"
 	LitInfoInitMemSetting   string = "[ddl-ingest] initial memory setting for lightning"
 	LitInfoUnsafeImport     string = "[ddl-ingest] do a partial import data into the storage"
+	LitErrCloseWriterErr    string = "[ddl-ingest] close writer error"
 )
 
 func genBackendAllocMemFailedErr(memRoot MemRoot, jobID int64) error {
diff --git a/tests/realtikvtest/addindextest/BUILD.bazel b/tests/realtikvtest/addindextest/BUILD.bazel
index f6bb2f0844404..62032320d03de 100644
--- a/tests/realtikvtest/addindextest/BUILD.bazel
+++ b/tests/realtikvtest/addindextest/BUILD.bazel
@@ -33,6 +33,7 @@ go_test(
     ],
     embed = [":addindextest"],
     deps = [
+        "//br/pkg/lightning/backend/local",
         "//config",
         "//ddl",
         "//ddl/ingest",
diff --git a/tests/realtikvtest/addindextest/integration_test.go b/tests/realtikvtest/addindextest/integration_test.go
index c29c6929fa8c3..35a636bec7be4 100644
--- a/tests/realtikvtest/addindextest/integration_test.go
+++ b/tests/realtikvtest/addindextest/integration_test.go
@@ -22,6 +22,7 @@ import (
 	"testing"
 
 	"github.com/pingcap/failpoint"
+	"github.com/pingcap/tidb/br/pkg/lightning/backend/local"
 	"github.com/pingcap/tidb/ddl"
 	"github.com/pingcap/tidb/ddl/ingest"
 	"github.com/pingcap/tidb/ddl/testutil"
@@ -38,6 +39,8 @@ func TestAddIndexIngestMemoryUsage(t *testing.T) {
 	tk.MustExec("use addindexlit;")
 	tk.MustExec(`set global tidb_ddl_enable_fast_reorg=on;`)
 
+	local.RunInTest = true
+
 	tk.MustExec("create table t (a int, b int, c int);")
 	var sb strings.Builder
 	sb.WriteString("insert into t values ")
@@ -55,6 +58,7 @@ func TestAddIndexIngestMemoryUsage(t *testing.T) {
 	tk.MustExec("alter table t add unique index idx1(b);")
 	tk.MustExec("admin check table t;")
 	require.Equal(t, int64(0), ingest.LitMemRoot.CurrentUsage())
+	require.NoError(t, local.LastAlloc.CheckRefCnt())
 }
 
 func TestAddIndexIngestLimitOneBackend(t *testing.T) {