inject 20% rate to go parallel logging and replaying

src/storage/tx/ob_trans_part_ctx.cpp

@@ -1862,10 +1862,17 @@ int ObPartTransCtx::serial_submit_redo_after_write_()
 bool ObPartTransCtx::should_switch_to_parallel_logging_()
 {
   const int64_t switch_size = GCONF._parallel_redo_logging_trigger;
-  return GCONF._enable_parallel_redo_logging
+  bool ok = GCONF._enable_parallel_redo_logging
     && is_support_parallel_replay_()
     && pending_write_ > 1
     && mt_ctx_.get_pending_log_size() > switch_size;
+#ifdef ENABLE_DEBUG_LOG
+  // inject
+  if (!ok && trans_id_ % 5 == 0) {
+    ok = GCONF._enable_parallel_redo_logging;
+  }
+#endif
+  return ok;
 }
 
 int ObPartTransCtx::check_can_submit_redo_()