diff --git a/src/storage/blocksstable/ob_micro_block_row_scanner.cpp b/src/storage/blocksstable/ob_micro_block_row_scanner.cpp
index a0fd36007..9c9d40d7d 100644
--- a/src/storage/blocksstable/ob_micro_block_row_scanner.cpp
+++ b/src/storage/blocksstable/ob_micro_block_row_scanner.cpp
@@ -1881,6 +1881,7 @@ int ObMultiVersionMicroBlockRowScanner::lock_for_read(
   int tmp_ret = OB_SUCCESS;
   SCN scn_trans_version = SCN::invalid_scn();
   auto &tx_table_guards = context_->store_ctx_->mvcc_acc_ctx_.get_tx_table_guards();
+  int64_t cost_time = common::ObClockGenerator::getClock();
 
   if (OB_FAIL(tx_table_guards.lock_for_read(lock_for_read_arg,
                                             can_read,
@@ -1897,6 +1898,12 @@ int ObMultiVersionMicroBlockRowScanner::lock_for_read(
         "sql_seq", lock_for_read_arg.data_sql_sequence_);
     }
   }
+  if (REACH_TENANT_TIME_INTERVAL(30 * 1000 * 1000 /*30s*/)) {
+    cost_time = common::ObClockGenerator::getClock() - cost_time;
+    if (cost_time > 10 * 1000 /*10ms*/) {
+      LOG_INFO("multi-ver row scanner lock for read", K(ret), K(cost_time));
+    }
+  }
   return ret;
 }
 
@@ -2798,6 +2805,7 @@ int ObMultiVersionMicroBlockMinorMergeRowScanner::check_curr_row_can_read(
     can_read = trans_state.can_read_;
   } else {
     storage::ObTxTableGuards &tx_table_guards = context_->store_ctx_->mvcc_acc_ctx_.get_tx_table_guards();
+    int64_t cost_time = common::ObClockGenerator::getClock();
     if (OB_FAIL(tx_table_guards.check_sql_sequence_can_read(
             trans_id,
             sql_seq,
@@ -2809,6 +2817,12 @@ int ObMultiVersionMicroBlockMinorMergeRowScanner::check_curr_row_can_read(
         committed_trans_version_, last_trans_state_, can_read))) {
       LOG_WARN("failed to add minor trans state", K(tmp_ret), K(trans_id), K(sql_seq), K(can_read));
     }
+    if (REACH_TENANT_TIME_INTERVAL(30 * 1000 * 1000 /*30s*/)) {
+      cost_time = common::ObClockGenerator::getClock() - cost_time;
+      if (cost_time > 10 * 1000 /*10ms*/) {
+        LOG_INFO("multi-ver minor row scanner check seq", K(ret), K(cost_time));
+      }
+    }
   }
   LOG_DEBUG("cxf debug check sql sequence can read", K(ret), K(can_read), K(trans_id), K(sql_seq));
   return ret;
diff --git a/src/storage/column_store/ob_column_oriented_merger.cpp b/src/storage/column_store/ob_column_oriented_merger.cpp
index 30f98cfa7..c5dae1687 100644
--- a/src/storage/column_store/ob_column_oriented_merger.cpp
+++ b/src/storage/column_store/ob_column_oriented_merger.cpp
@@ -388,7 +388,9 @@ int ObCOMerger::write_residual_data()
 
   for (int64_t i = 0; OB_SUCC(ret) && i < merge_writers_.count(); i++) {
     ObCOMergeWriter *merge_writer = nullptr;
-    if (OB_ISNULL(merge_writer = merge_writers_.at(i))) {
+    if (OB_FAIL(share::dag_yield())) {
+      STORAGE_LOG(WARN, "fail to yield co merge dag", KR(ret));
+    } else if (OB_ISNULL(merge_writer = merge_writers_.at(i))) {
       ret = OB_ERR_UNEXPECTED;
       STORAGE_LOG(WARN, "UNEXPECTED null writer", K(ret));
     } else if (OB_FAIL(merge_writer->append_residual_data())) {
diff --git a/src/storage/tx/ob_trans_ctx_mgr_v4.cpp b/src/storage/tx/ob_trans_ctx_mgr_v4.cpp
index 3d76ee5b0..34f81d711 100644
--- a/src/storage/tx/ob_trans_ctx_mgr_v4.cpp
+++ b/src/storage/tx/ob_trans_ctx_mgr_v4.cpp
@@ -587,6 +587,13 @@ int ObLSTxCtxMgr::get_tx_ctx_(const ObTransID &tx_id, const bool for_replay, ObP
       TRANS_LOG(INFO, "transaction statistics", K_(ls_id),
           "total_tx_ctx_count", get_tx_ctx_count_());
     }
+#ifdef ENABLE_DEBUG_LOG
+    // ENABLE_DEBUG_LOG macro only defined in inner test environment
+    if (REACH_TIME_INTERVAL(3 * 60 * 1000 * 1000 /*3 min*/)) {
+      TRANS_LOG(INFO, "transaction statistics", K_(ls_id),
+          "total_tx_ctx_count", get_tx_ctx_count_(), K(lbt()));
+    }
+#endif
   }
   return ret;
 }