diff --git a/AlgebraicDataflowArchitectureModel/src/experiment/PullExpriment.java b/AlgebraicDataflowArchitectureModel/src/experiment/PullExpriment.java
index 5dad46b..cfcb0ab 100644
--- a/AlgebraicDataflowArchitectureModel/src/experiment/PullExpriment.java
+++ b/AlgebraicDataflowArchitectureModel/src/experiment/PullExpriment.java
@@ -12,6 +12,7 @@
 			long startTime = System.nanoTime();
 			main.purchase(100);
 			long endTime = System.nanoTime();
+			main.getHistory().clear();
 			times += endTime - startTime;
 		}
 		System.out.println("purchase:" + times / num);