diff --git a/src/util/src/tref.c b/src/util/src/tref.c
index ebae8ece14e2f3bd045fee92482afa4c6c403949..5c7bdec01eb57cb8ee561d10a8417daf15d90bcd 100644
--- a/src/util/src/tref.c
+++ b/src/util/src/tref.c
@@ -24,22 +24,22 @@
 #define TSDB_REF_STATE_DELETED 2
 
 typedef struct SRefNode {
-  struct SRefNode  *prev;  // previous node 
+  struct SRefNode  *prev;  // previous node
   struct SRefNode  *next;  // next node
-  void             *p;     // pointer to resource protected, 
+  void             *p;     // pointer to resource protected,
   int64_t           rid;   // reference ID
   int32_t           count; // number of references
-  int               removed; // 1: removed 
+  int               removed; // 1: removed
 } SRefNode;
 	
 typedef struct {
   SRefNode **nodeList; // array of SRefNode linked list
   int        state;    // 0: empty, 1: active;  2: deleted
-  int        rsetId;   // refSet ID, global unique 
+  int        rsetId;   // refSet ID, global unique
   int64_t    rid;      // increase by one for each new reference
-  int        max;      // mod 
+  int        max;      // mod
   int32_t    count;    // total number of SRefNodes in this set
-  int64_t   *lockedBy; 
+  int64_t   *lockedBy;
   void     (*fp)(void *);
 } SRefSet;
 
@@ -62,9 +62,9 @@ int taosOpenRef(int max, void (*fp)(void *))
   SRefSet   *pSet;
   int64_t   *lockedBy;
   int        i, rsetId;
-  
+
   pthread_once(&tsRefModuleInit, taosInitRefModule);
-   
+
   nodeList = calloc(sizeof(SRefNode *), (size_t)max);
   if (nodeList == NULL)  {
     terrno = TSDB_CODE_REF_NO_MEMORY;
@@ -79,12 +79,12 @@ int taosOpenRef(int max, void (*fp)(void *))
   }
 
   pthread_mutex_lock(&tsRefMutex);
- 
+
   for (i = 0; i < TSDB_REF_OBJECTS; ++i) {
     tsNextId = (tsNextId + 1) % TSDB_REF_OBJECTS;
     if (tsNextId == 0) tsNextId = 1;   // dont use 0 as rsetId
     if (tsRefSetList[tsNextId].state == TSDB_REF_STATE_EMPTY) break;
-  } 
+  }
 
   if (i < TSDB_REF_OBJECTS) {
     rsetId = tsNextId;
@@ -105,7 +105,7 @@ int taosOpenRef(int max, void (*fp)(void *))
     free (nodeList);
     free (lockedBy);
     uTrace("run out of Ref ID, maximum:%d refSetNum:%d", TSDB_REF_OBJECTS, tsRefSetNum);
-  } 
+  }
 
   pthread_mutex_unlock(&tsRefMutex);
 
@@ -127,7 +127,7 @@ int taosCloseRef(int rsetId)
 
   pthread_mutex_lock(&tsRefMutex);
 
-  if (pSet->state == TSDB_REF_STATE_ACTIVE) { 
+  if (pSet->state == TSDB_REF_STATE_ACTIVE) {
     pSet->state = TSDB_REF_STATE_DELETED;
     deleted = 1;
     uTrace("rsetId:%d is closed, count:%d", rsetId, pSet->count);
@@ -142,7 +142,7 @@ int taosCloseRef(int rsetId)
   return 0;
 }
 
-int64_t taosAddRef(int rsetId, void *p) 
+int64_t taosAddRef(int rsetId, void *p)
 {
   int       hash;
   SRefNode *pNode;
@@ -163,7 +163,7 @@ int64_t taosAddRef(int rsetId, void *p)
     terrno = TSDB_CODE_REF_ID_REMOVED;
     return -1;
   }
-  
+
   pNode = calloc(sizeof(SRefNode), 1);
   if (pNode == NULL) {
     terrno = TSDB_CODE_REF_NO_MEMORY;
@@ -173,7 +173,7 @@ int64_t taosAddRef(int rsetId, void *p)
   rid = atomic_add_fetch_64(&pSet->rid, 1);
   hash = rid % pSet->max;
   taosLockList(pSet->lockedBy+hash);
-  
+
   pNode->p = p;
   pNode->rid = rid;
   pNode->count = 1;
@@ -187,16 +187,16 @@ int64_t taosAddRef(int rsetId, void *p)
 
   taosUnlockList(pSet->lockedBy+hash);
 
-  return rid; 
+  return rid;
 }
 
-int taosRemoveRef(int rsetId, int64_t rid) 
+int taosRemoveRef(int rsetId, int64_t rid)
 {
   return taosDecRefCount(rsetId, rid, 1);
 }
 
 // if rid is 0, return the first p in hash list, otherwise, return the next after current rid
-void *taosAcquireRef(int rsetId, int64_t rid) 
+void *taosAcquireRef(int rsetId, int64_t rid)
 {
   int       hash;
   SRefNode *pNode;
@@ -223,7 +223,7 @@ void *taosAcquireRef(int rsetId, int64_t rid)
     terrno = TSDB_CODE_REF_ID_REMOVED;
     return NULL;
   }
-  
+
   hash = rid % pSet->max;
   taosLockList(pSet->lockedBy+hash);
 
@@ -233,8 +233,8 @@ void *taosAcquireRef(int rsetId, int64_t rid)
     if (pNode->rid == rid) {
       break;
     }
-      
-    pNode = pNode->next;   
+
+    pNode = pNode->next;
   }
 
   if (pNode) {
@@ -258,7 +258,7 @@ void *taosAcquireRef(int rsetId, int64_t rid)
   return p;
 }
 
-int taosReleaseRef(int rsetId, int64_t rid) 
+int taosReleaseRef(int rsetId, int64_t rid)
 {
   return taosDecRefCount(rsetId, rid, 0);
 }
@@ -280,6 +280,7 @@ void *taosIterateRef(int rsetId, int64_t rid) {
     return NULL;
   }
 
+  void *newP = NULL;
   pSet = tsRefSetList + rsetId;
   taosIncRsetCount(pSet);
   if (pSet->state != TSDB_REF_STATE_ACTIVE) {
@@ -289,52 +290,68 @@ void *taosIterateRef(int rsetId, int64_t rid) {
     return NULL;
   }
 
-  int hash = 0;
-  if (rid > 0) {
-    hash = rid % pSet->max;
-    taosLockList(pSet->lockedBy+hash);
+  do {
+    newP = NULL;
+    int hash = 0;
+    if (rid > 0) {
+      hash = rid % pSet->max;
+      taosLockList(pSet->lockedBy+hash);
+
+      pNode = pSet->nodeList[hash];
+      while (pNode) {
+        if (pNode->rid == rid) break;
+        pNode = pNode->next;
+      }
 
-    pNode = pSet->nodeList[hash];
-    while (pNode) {
-      if (pNode->rid == rid) break;
-      pNode = pNode->next;   
-    }
+      if (pNode == NULL) {
+        uError("rsetId:%d rid:%" PRId64 " not there, quit", rsetId, rid);
+        terrno = TSDB_CODE_REF_NOT_EXIST;
+        taosUnlockList(pSet->lockedBy+hash);
+        taosDecRsetCount(pSet);
+        return NULL;
+      }
 
-    if (pNode == NULL) {
-      uError("rsetId:%d rid:%" PRId64 " not there, quit", rsetId, rid);
-      terrno = TSDB_CODE_REF_NOT_EXIST;
-      taosUnlockList(pSet->lockedBy+hash);
-      return NULL;
+      // rid is there
+      pNode = pNode->next;
+      // check first place
+      while (pNode) {
+        if (!pNode->removed) break;
+        pNode = pNode->next;
+      }
+      if (pNode == NULL) {
+        taosUnlockList(pSet->lockedBy+hash);
+        hash++;
+      }
     }
 
-    // rid is there
-    pNode = pNode->next;
-    if (pNode == NULL) { 
-      taosUnlockList(pSet->lockedBy+hash);
-      hash++;
+    if (pNode == NULL) {
+      for (; hash < pSet->max; ++hash) {
+        taosLockList(pSet->lockedBy+hash);
+        pNode = pSet->nodeList[hash];
+        if (pNode) {
+          // check first place
+          while (pNode) {
+            if (!pNode->removed) break;
+            pNode = pNode->next;
+          }
+          if (pNode) break;
+        }
+        taosUnlockList(pSet->lockedBy+hash);
+      }
     }
-  }
 
-  if (pNode == NULL) {
-    for (; hash < pSet->max; ++hash) {
-      taosLockList(pSet->lockedBy+hash);
-      pNode = pSet->nodeList[hash];
-      if (pNode) break; 
+    if (pNode) {
+      pNode->count++;  // acquire it
+      newP = pNode->p;
       taosUnlockList(pSet->lockedBy+hash);
+      uTrace("rsetId:%d p:%p rid:%" PRId64 " is returned", rsetId, newP, rid);
+    } else {
+      uTrace("rsetId:%d the list is over", rsetId);
     }
-  } 
 
-  void *newP = NULL;
-  if (pNode) {
-    pNode->count++;  // acquire it
-    newP = pNode->p;  
-    taosUnlockList(pSet->lockedBy+hash);
-    uTrace("rsetId:%d p:%p rid:%" PRId64 " is returned", rsetId, newP, rid); 
-  } else {
-    uTrace("rsetId:%d the list is over", rsetId);
-  }
-
-  if (rid > 0) taosReleaseRef(rsetId, rid);  // release the current one
+    if (rid > 0) taosReleaseRef(rsetId, rid);  // release the current one
+    if (pNode) rid = pNode->rid;
+  } while (newP && pNode->removed);
 
   taosDecRsetCount(pSet);
 
@@ -350,22 +367,22 @@ int taosListRef() {
 
   for (int i = 0; i < TSDB_REF_OBJECTS; ++i) {
     pSet = tsRefSetList + i;
-    
-    if (pSet->state == TSDB_REF_STATE_EMPTY) 
+
+    if (pSet->state == TSDB_REF_STATE_EMPTY)
       continue;
 
     uInfo("rsetId:%d state:%d count::%d", i, pSet->state, pSet->count);
 
     for (int j=0; j < pSet->max; ++j) {
       pNode = pSet->nodeList[j];
-     
+
       while (pNode) {
         uInfo("rsetId:%d p:%p rid:%" PRId64 "count:%d", i, pNode->p, pNode->rid, pNode->count);
         pNode = pNode->next;
         num++;
       }
-    }  
-  } 
+    }
+  }
 
   pthread_mutex_unlock(&tsRefMutex);
 
@@ -397,16 +414,16 @@ static int taosDecRefCount(int rsetId, int64_t rid, int remove) {
     terrno = TSDB_CODE_REF_ID_REMOVED;
     return -1;
   }
-  
+
   hash = rid % pSet->max;
   taosLockList(pSet->lockedBy+hash);
-  
+
   pNode = pSet->nodeList[hash];
   while (pNode) {
     if (pNode->rid == rid)
       break;
 
-    pNode = pNode->next;  
+    pNode = pNode->next;
   }
 
   if (pNode) {
@@ -417,18 +434,18 @@ static int taosDecRefCount(int rsetId, int64_t rid, int remove) {
       if (pNode->prev) {
         pNode->prev->next = pNode->next;
       } else {
-        pSet->nodeList[hash] = pNode->next;  
+        pSet->nodeList[hash] = pNode->next;
       }
 		
       if (pNode->next) {
-        pNode->next->prev = pNode->prev; 
-      } 
+        pNode->next->prev = pNode->prev;
+      }
       released = 1;
     } else {
-       uTrace("rsetId:%d p:%p rid:%" PRId64 " is released", rsetId, pNode->p, rid); 
+       uTrace("rsetId:%d p:%p rid:%" PRId64 " is released", rsetId, pNode->p, rid);
     }
   } else {
-    uTrace("rsetId:%d rid:%" PRId64 " is not there, failed to release/remove", rsetId, rid); 
+    uTrace("rsetId:%d rid:%" PRId64 " is not there, failed to release/remove", rsetId, rid);
     terrno = TSDB_CODE_REF_NOT_EXIST;
     code = -1;
   }
@@ -437,11 +454,11 @@ static int taosDecRefCount(int rsetId, int64_t rid, int remove) {
 
   if (released) {
     uTrace("rsetId:%d p:%p rid:%" PRId64 " is removed, count:%d, free mem: %p", rsetId, pNode->p, rid, pSet->count, pNode);
-    (*pSet->fp)(pNode->p); 
+    (*pSet->fp)(pNode->p);
     free(pNode);
 
     taosDecRsetCount(pSet);
-  } 
+  }
 
   return code;
 }
@@ -493,5 +510,5 @@ static void taosDecRsetCount(SRefSet *pSet) {
   }
 
   pthread_mutex_unlock(&tsRefMutex);
-} 
+}