diff --git a/be/src/olap/rowset/beta_rowset_writer.cpp b/be/src/olap/rowset/beta_rowset_writer.cpp
index 745b5135c8..4f1c95568a 100644
--- a/be/src/olap/rowset/beta_rowset_writer.cpp
+++ b/be/src/olap/rowset/beta_rowset_writer.cpp
@@ -292,8 +292,9 @@ RowsetSharedPtr BetaRowsetWriter::build_tmp() {
 
 Status BetaRowsetWriter::_create_segment_writer(
         std::unique_ptr<segment_v2::SegmentWriter>* writer) {
-    auto path = BetaRowset::local_segment_path(_context.tablet_path, _context.rowset_id,
-                                               _num_segment++);
+    int32_t segment_id = _num_segment.fetch_add(1);
+    auto path =
+            BetaRowset::local_segment_path(_context.tablet_path, _context.rowset_id, segment_id);
     auto fs = _rowset_meta->fs();
     if (!fs) {
         return Status::OLAPInternalError(OLAP_ERR_INIT_FAILED);
@@ -309,7 +310,7 @@ Status BetaRowsetWriter::_create_segment_writer(
     DCHECK(file_writer != nullptr);
     segment_v2::SegmentWriterOptions writer_options;
     writer_options.enable_unique_key_merge_on_write = _context.enable_unique_key_merge_on_write;
-    writer->reset(new segment_v2::SegmentWriter(file_writer.get(), _num_segment,
+    writer->reset(new segment_v2::SegmentWriter(file_writer.get(), segment_id,
                                                 _context.tablet_schema, _context.data_dir,
                                                 _context.max_rows_per_segment, writer_options));
     {
@@ -327,7 +328,6 @@ Status BetaRowsetWriter::_create_segment_writer(
 }
 
 Status BetaRowsetWriter::_flush_segment_writer(std::unique_ptr<segment_v2::SegmentWriter>* writer) {
-    _segment_num_rows.push_back((*writer)->num_rows_written());
     if ((*writer)->num_rows_written() == 0) {
         return Status::OK();
     }
@@ -346,7 +346,13 @@ Status BetaRowsetWriter::_flush_segment_writer(std::unique_ptr<segment_v2::Segme
     DCHECK_LE(min_key.compare(max_key), 0);
     key_bounds.set_min_key(min_key.to_string());
     key_bounds.set_max_key(max_key.to_string());
-    _segments_encoded_key_bounds.emplace_back(key_bounds);
+    {
+        std::lock_guard<SpinLock> l(_lock);
+        _segment_num_rows.resize(_num_segment);
+        _segments_encoded_key_bounds.resize(_num_segment);
+        _segment_num_rows[(*writer)->get_segment_id()] = (*writer)->num_rows_written();
+        _segments_encoded_key_bounds[(*writer)->get_segment_id()] = key_bounds;
+    }
     writer->reset();
     return Status::OK();
 }
diff --git a/be/src/olap/rowset/beta_rowset_writer.h b/be/src/olap/rowset/beta_rowset_writer.h
index afa15b4018..5980fae81e 100644
--- a/be/src/olap/rowset/beta_rowset_writer.h
+++ b/be/src/olap/rowset/beta_rowset_writer.h
@@ -69,6 +69,7 @@ public:
     RowsetTypePB type() const override { return RowsetTypePB::BETA_ROWSET; }
 
     Status get_segment_num_rows(std::vector<uint32_t>* segment_num_rows) const override {
+        std::lock_guard<SpinLock> l(_lock);
         *segment_num_rows = _segment_num_rows;
         return Status::OK();
     }
@@ -93,8 +94,13 @@ private:
     /// Because we want to flush memtables in parallel.
     /// In other processes, such as merger or schema change, we will use this unified writer for data writing.
     std::unique_ptr<segment_v2::SegmentWriter> _segment_writer;
-    mutable SpinLock _lock; // lock to protect _wblocks.
+
+    mutable SpinLock _lock; // protect following vectors.
     std::vector<io::FileWriterPtr> _file_writers;
+    // for unique key table with merge-on-write
+    std::vector<KeyBoundsPB> _segments_encoded_key_bounds;
+    // record rows number of every segment
+    std::vector<uint32_t> _segment_num_rows;
 
     // counters and statistics maintained during data write
     std::atomic<int64_t> _num_rows_written;
@@ -104,11 +110,6 @@ private:
 
     bool _is_pending = false;
     bool _already_built = false;
-
-    // for unique key table with merge-on-write
-    std::vector<KeyBoundsPB> _segments_encoded_key_bounds;
-    // record rows number of every segment
-    std::vector<uint32_t> _segment_num_rows;
 };
 
 } // namespace doris
diff --git a/be/src/olap/rowset/segment_v2/segment_writer.h b/be/src/olap/rowset/segment_v2/segment_writer.h
index 636adb05bf..590bfa7a91 100644
--- a/be/src/olap/rowset/segment_v2/segment_writer.h
+++ b/be/src/olap/rowset/segment_v2/segment_writer.h
@@ -84,6 +84,7 @@ public:
 
     static void init_column_meta(ColumnMetaPB* meta, uint32_t* column_id,
                                  const TabletColumn& column, TabletSchemaSPtr tablet_schema);
+    uint32_t get_segment_id() { return _segment_id; }
     Slice min_encoded_key();
     Slice max_encoded_key();