[CP] [3_1_x] fix unsafe access part_ctx member in iter_trans_stat

src/storage/transaction/ob_trans_functor.h

@@ -741,6 +741,7 @@ public:
         // If the transaction has not completed in 600 seconds, print its trace log
         part_ctx->print_trace_log();
       }
+      /* _NOTICE_: must acquire part_ctx's lock when accessing member of imprimitive type */
       if (OB_SUCCESS == tmp_ret) {
         ObPartitionArray participants_arr(
             common::ObModIds::OB_TRANS_PARTITION_ARRAY, common::OB_MALLOC_NORMAL_BLOCK_SIZE);

src/storage/transaction/ob_trans_part_ctx.cpp

@@ -12146,7 +12146,13 @@ int64_t ObPartTransCtx::get_part_trans_action() const
 
   if (ObPartTransAction::UNKNOWN == action) {
     if (stmt_info_.get_sql_no() > 0) {
-      action = stmt_info_.is_task_match() ? ObPartTransAction::END_TASK : ObPartTransAction::START_TASK;
+      int ret = OB_SUCCESS;
+      if (OB_FAIL(lock_.try_lock())) {
+        TRANS_LOG(INFO, "lock fail to get part_trans_action", K(ret), K_(trans_id), K_(self), KP(this));
+      } else {
+        action = stmt_info_.is_task_match() ? ObPartTransAction::END_TASK : ObPartTransAction::START_TASK;
+        lock_.unlock();
+      }
     }
   }