diff --git a/src/main/java/org/bdware/server/action/p2p/MasterClientTCPAction.java b/src/main/java/org/bdware/server/action/p2p/MasterClientTCPAction.java
index f1b6a87..f54aa3e 100644
--- a/src/main/java/org/bdware/server/action/p2p/MasterClientTCPAction.java
+++ b/src/main/java/org/bdware/server/action/p2p/MasterClientTCPAction.java
@@ -80,8 +80,8 @@ public class MasterClientTCPAction {
                     request.get("verifiedPubKey").getAsString(), client.getContractID());
             MultiContractMeta cei =
                     CMActions.manager.multiContractRecorder.getMultiContractMeta(client.getContractID());
-            if (null != cei && cei.contractExecutor instanceof SelfAdaptiveShardingExecutor) {
-                ((SelfAdaptiveShardingExecutor) cei.contractExecutor).close();
+            if (null != cei) {
+                cei.contractExecutor.close();
             }
         }
     }
diff --git a/src/main/java/org/bdware/server/trustedmodel/SelfAdaptiveShardingExecutor.java b/src/main/java/org/bdware/server/trustedmodel/SelfAdaptiveShardingExecutor.java
index 309c040..f2d0f48 100644
--- a/src/main/java/org/bdware/server/trustedmodel/SelfAdaptiveShardingExecutor.java
+++ b/src/main/java/org/bdware/server/trustedmodel/SelfAdaptiveShardingExecutor.java
@@ -48,7 +48,7 @@ public class SelfAdaptiveShardingExecutor implements ContractExecutor {
                 TimeUnit.SECONDS);
         ContractManager.threadPool.submit(() -> {
             LOGGER.info(
-                    "[SelfAdaptiveShardingExecutor " + meta.getContractID() + "] starting service...");
+                    "[SelfAdaptiveShardingExecutor " + meta.getContractID() + "] starting service..." + running);
             while (running) {
                 LOGGER.info("checking blocks to be executed, latest block=" +
                         this.b.prevHash + ", to be executed size=" + toExecuted.size());
@@ -75,12 +75,6 @@ public class SelfAdaptiveShardingExecutor implements ContractExecutor {
         });
     }
 
-    public void close() {
-        this.future.cancel(false);
-        this.running = false;
-        LOGGER.info("destruct executor of contract " + meta.getContractID());
-    }
-
     @Override
     public void execute(String requestID, ResultCallback rc, ContractRequest req) {
         if (executedTxs.containsKey(requestID)) {
@@ -100,6 +94,13 @@ public class SelfAdaptiveShardingExecutor implements ContractExecutor {
         }
     }
 
+    @Override
+    public void close() {
+        this.future.cancel(false);
+        this.running = false;
+        LOGGER.info("destruct executor of contract " + meta.getContractID());
+    }
+
     public void execute(String blockStr) {
         Block block = JsonUtil.fromJson(blockStr, Block.class);
         if (!toExecuted.containsKey(block.prevHash) &&
@@ -129,6 +130,7 @@ public class SelfAdaptiveShardingExecutor implements ContractExecutor {
                 return;
             }
         }
+        // TODO check status
         for (ContractRequest request : block.requests) {
             String ret = ContractManager.instance.executeLocally(request, null);
             LOGGER.debug("result of request " + request.getRequestID() + ": " + ret);
@@ -139,6 +141,7 @@ public class SelfAdaptiveShardingExecutor implements ContractExecutor {
                 meta.getContractID(),
                 block.requests.length,
                 block.hash));
+        // TODO create check point
         this.b = new Block(block.hash);
         executedBlocks.add(block.hash);
     }
@@ -211,7 +214,6 @@ public class SelfAdaptiveShardingExecutor implements ContractExecutor {
                     this.body);
         }
 
-
         private String merkle(ContractRequest[] requests) {
             if (requests.length == 0) {
                 return null;