diff --git a/contracts/BSCValidatorSet.sol b/contracts/BSCValidatorSet.sol
index 4b9507a3..8002e52e 100644
--- a/contracts/BSCValidatorSet.sol
+++ b/contracts/BSCValidatorSet.sol
@@ -364,189 +364,56 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
     }
   }
 
-  function updateValidatorSet(Validator[] memory validatorSet, bytes[] memory voteAddrs) internal returns (uint32) {
-    {
-      // do verify.
-      if (validatorSet.length > MAX_NUM_OF_VALIDATORS) {
-        emit failReasonWithStr("the number of validators exceed the limit");
-        return ERROR_FAIL_CHECK_VALIDATORS;
-      }
-      for (uint i; i<validatorSet.length; ++i) {
-        for (uint j; j<i; ++j) {
-          if (validatorSet[i].consensusAddress == validatorSet[j].consensusAddress) {
-            emit failReasonWithStr("duplicate consensus address of validatorSet");
-            return ERROR_FAIL_CHECK_VALIDATORS;
-          }
-        }
-      }
-    }
-
-    // step 0: force all maintaining validators to exit `Temporary Maintenance`
-    // - 1. validators exit maintenance
-    // - 2. clear all maintainInfo
-    // - 3. get unjailed validators from validatorSet
-    Validator[] memory validatorSetTemp;
-    bytes[] memory voteAddrsTemp;
-    {
-      // get migrated validators
-      Validator[] memory bscValidatorSet = _tmpMigratedValidatorSet;
-      bytes[] memory bscVoteAddrs = _tmpMigratedVoteAddrs;
-      for (uint256 i; i < bscValidatorSet.length; ++i) {
-        bscValidatorSet[i].votingPower = bscValidatorSet[i].votingPower * 3; // amplify the voting power for BSC validators
-      }
-      (Validator[] memory mergedValidators, bytes[] memory mergedVoteAddrs) = _mergeValidatorSet(validatorSet, voteAddrs, bscValidatorSet, bscVoteAddrs);
-
-      (validatorSetTemp, voteAddrsTemp) = _forceMaintainingValidatorsExit(mergedValidators, mergedVoteAddrs);
-    }
-
-    {
-      //step 1: do calculate distribution, do not make it as an internal function for saving gas.
-      uint crossSize;
-      uint directSize;
-      uint validatorsNum = currentValidatorSet.length;
-      uint8[] memory isMigrated = new uint8[](validatorsNum);
-      for (uint i; i<validatorsNum; ++i) {
-        if (IStakeHub(STAKE_HUB_ADDR).consensusToOperator(currentValidatorSet[i].consensusAddress) != address(0)) {
-          isMigrated[i] = 1;
-          if (currentValidatorSet[i].incoming != 0) {
-            ++ directSize;
-          }
-        } else if (currentValidatorSet[i].incoming >= DUSTY_INCOMING) {
-          ++ crossSize;
-        } else if (currentValidatorSet[i].incoming != 0) {
-          ++ directSize;
-        }
-      }
-
-      //cross transfer
-      address[] memory crossAddrs = new address[](crossSize);
-      uint256[] memory crossAmounts = new uint256[](crossSize);
-      uint256[] memory crossIndexes = new uint256[](crossSize);
-      address[] memory crossRefundAddrs = new address[](crossSize);
-      uint256 crossTotal;
-      // direct transfer
-      address payable[] memory directAddrs = new address payable[](directSize);
-      uint256[] memory directAmounts = new uint256[](directSize);
-      crossSize = 0;
-      directSize = 0;
-      uint256 relayFee = ITokenHub(TOKEN_HUB_ADDR).getMiniRelayFee();
-      if (relayFee > DUSTY_INCOMING) {
-        emit failReasonWithStr("fee is larger than DUSTY_INCOMING");
-        return ERROR_RELAYFEE_TOO_LARGE;
-      }
-      for (uint i; i < validatorsNum; ++i) {
-        if (isMigrated[i] == 1) {
-          if (currentValidatorSet[i].incoming != 0) {
-            directAddrs[directSize] = payable(currentValidatorSet[i].consensusAddress);
-            directAmounts[directSize] = currentValidatorSet[i].incoming;
-            isMigrated[directSize] = 1; // directSize must be less than i. so we can use directSize as index
-            ++directSize;
-          }
-        } else if (currentValidatorSet[i].incoming >= DUSTY_INCOMING) {
-          crossAddrs[crossSize] = currentValidatorSet[i].BBCFeeAddress;
-          uint256 value = currentValidatorSet[i].incoming - currentValidatorSet[i].incoming % PRECISION;
-          crossAmounts[crossSize] = value.sub(relayFee);
-          crossRefundAddrs[crossSize] = currentValidatorSet[i].feeAddress;
-          crossIndexes[crossSize] = i;
-          crossTotal = crossTotal.add(value);
-          ++crossSize;
-        } else if (currentValidatorSet[i].incoming != 0) {
-          directAddrs[directSize] = currentValidatorSet[i].feeAddress;
-          directAmounts[directSize] = currentValidatorSet[i].incoming;
-          isMigrated[directSize] = 0;
-          ++directSize;
-        }
-      }
-
-      //step 2: do cross chain transfer
-      bool failCross = false;
-      if (crossTotal > 0) {
-        try ITokenHub(TOKEN_HUB_ADDR).batchTransferOutBNB{value : crossTotal}(crossAddrs, crossAmounts, crossRefundAddrs, uint64(block.timestamp + expireTimeSecondGap)) returns (bool success) {
-          if (success) {
-            emit batchTransfer(crossTotal);
-          } else {
-            emit batchTransferFailed(crossTotal, "batch transfer return false");
-          }
-        }catch Error(string memory reason) {
-          failCross = true;
-          emit batchTransferFailed(crossTotal, reason);
-        }catch (bytes memory lowLevelData) {
-          failCross = true;
-          emit batchTransferLowerFailed(crossTotal, lowLevelData);
-        }
-      }
-
-      if (failCross) {
-        for (uint i; i<crossIndexes.length; ++i) {
-          uint idx = crossIndexes[i];
-          bool success = currentValidatorSet[idx].feeAddress.send(currentValidatorSet[idx].incoming);
-          if (success) {
-            emit directTransfer(currentValidatorSet[idx].feeAddress, currentValidatorSet[idx].incoming);
-          } else {
-            emit directTransferFail(currentValidatorSet[idx].feeAddress, currentValidatorSet[idx].incoming);
-          }
-        }
-      }
-
-      // step 3: direct transfer
-      if (directAddrs.length > 0) {
-        for (uint i; i < directAddrs.length; ++i) {
-          if (isMigrated[i] == 1) {
-            IStakeHub(STAKE_HUB_ADDR).distributeReward{value : directAmounts[i]}(directAddrs[i]);
-          } else {
-            bool success = directAddrs[i].send(directAmounts[i]);
-            if (success) {
-              emit directTransfer(directAddrs[i], directAmounts[i]);
-            } else {
-              emit directTransferFail(directAddrs[i], directAmounts[i]);
-            }
-          }
-        }
-      }
+  function distributeFinalityReward(address[] calldata valAddrs, uint256[] calldata weights) external onlyCoinbase oncePerBlock onlyZeroGasPrice onlyInit {
+    uint256 totalValue;
+    uint256 balanceOfSystemReward = address(SYSTEM_REWARD_ADDR).balance;
+    if (balanceOfSystemReward > MAX_SYSTEM_REWARD_BALANCE) {
+      // when a slash happens, theres will no rewards in some epochs,
+      // it's tolerated because slash happens rarely
+      totalValue = balanceOfSystemReward.sub(MAX_SYSTEM_REWARD_BALANCE);
+    } else {
+      return;
     }
 
-    for (uint i; i < currentValidatorSet.length; ++i) {
-      if (currentValidatorSet[i].incoming != 0) {
-          currentValidatorSet[i].incoming = 0;
-      }
+    totalValue = ISystemReward(SYSTEM_REWARD_ADDR).claimRewards(payable(address(this)), totalValue);
+    if (totalValue == 0) {
+      return;
     }
 
-    // step 4: do dusk transfer
-    if (address(this).balance>0) {
-      emit systemTransfer(address(this).balance);
-      address(uint160(SYSTEM_REWARD_ADDR)).transfer(address(this).balance);
+    uint256 totalWeight;
+    for (uint256 i; i<weights.length; ++i) {
+      totalWeight += weights[i];
     }
-
-    // step 5: do update validator set state
-    totalInComing = 0;
-    numOfJailed = 0;
-    if (validatorSetTemp.length > 0) {
-      doUpdateState(validatorSetTemp, voteAddrsTemp);
+    if (totalWeight == 0) {
+      return;
     }
 
-    // step 6: clean slash contract
-    ISlashIndicator(SLASH_CONTRACT_ADDR).clean();
-    emit validatorSetUpdated();
-    return CODE_OK;
-  }
+    uint256 value;
+    address valAddr;
+    uint256 index;
 
-  /**
-   * @dev With each epoch, there will be a partial rotation between cabinets and candidates. Rotation is determined by this function
-   */
-  function shuffle(address[] memory validators, bytes[] memory voteAddrs, uint256 epochNumber, uint startIdx, uint offset, uint limit, uint modNumber) internal pure {
-    for (uint i; i<limit; ++i) {
-      uint random = uint(keccak256(abi.encodePacked(epochNumber, startIdx+i))) % modNumber;
-      if ( (startIdx+i) != (offset+random) ) {
-        address tmpAddr = validators[startIdx+i];
-        bytes memory tmpBLS = voteAddrs[startIdx+i];
-        validators[startIdx+i] = validators[offset+random];
-        validators[offset+random] = tmpAddr;
-        voteAddrs[startIdx+i] = voteAddrs[offset+random];
-        voteAddrs[offset+random] = tmpBLS;
+    for (uint256 i; i<valAddrs.length; ++i) {
+      value = (totalValue * weights[i]) / totalWeight;
+      valAddr = valAddrs[i];
+      index = currentValidatorSetMap[valAddr];
+      if (index > 0) {
+        Validator storage validator = currentValidatorSet[index - 1];
+        if (validator.jailed) {
+          emit deprecatedFinalityRewardDeposit(valAddr, value);
+        } else {
+          totalInComing = totalInComing.add(value);
+          validator.incoming = validator.incoming.add(value);
+          emit finalityRewardDeposit(valAddr, value);
+        }
+      } else {
+        // get incoming from deprecated validator;
+        emit deprecatedFinalityRewardDeposit(valAddr, value);
       }
     }
+
   }
 
+  /*********************** View Functions **************************/
   /**
    * @notice Return the vote address and consensus address of the validators in `currentValidatorSet` that are not jailed
    */
@@ -636,8 +503,20 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
     return consensusAddrs;
   }
 
+  /**
+   * @notice Return the current incoming of the validator
+   */
+  function getIncoming(address validator) external view returns(uint256) {
+    uint256 index = currentValidatorSetMap[validator];
+    if (index<=0) {
+      return 0;
+    }
+    return currentValidatorSet[index-1].incoming;
+  }
+
   /**
    * @notice Return whether the validator is a working validator(not jailed or maintaining) by index
+   * Will return false if the validator is not in `currentValidatorSet`
    *
    * @param index The index of the validator in `currentValidatorSet`(from 0 to `currentValidatorSet.length-1`)
    */
@@ -654,17 +533,6 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
     return !currentValidatorSet[index].jailed && !validatorExtraSet[index].isMaintaining;
   }
 
-  /**
-   * @notice Return the current incoming of the validator
-   */
-  function getIncoming(address validator)external view returns(uint256) {
-    uint256 index = currentValidatorSetMap[validator];
-    if (index<=0) {
-      return 0;
-    }
-    return currentValidatorSet[index-1].incoming;
-  }
-
   /**
    * @notice Return whether the validator is a working validator(not jailed or maintaining) by consensus address
    * Will return false if the validator is not in `currentValidatorSet`
@@ -680,63 +548,25 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
     return isWorkingValidator(index);
   }
 
-  function distributeFinalityReward(address[] calldata valAddrs, uint256[] calldata weights) external onlyCoinbase oncePerBlock onlyZeroGasPrice onlyInit {
-    uint256 totalValue;
-    uint256 balanceOfSystemReward = address(SYSTEM_REWARD_ADDR).balance;
-    if (balanceOfSystemReward > MAX_SYSTEM_REWARD_BALANCE) {
-      // when a slash happens, theres will no rewards in some epochs,
-      // it's tolerated because slash happens rarely
-      totalValue = balanceOfSystemReward.sub(MAX_SYSTEM_REWARD_BALANCE);
-    } else {
-      return;
-    }
-
-    totalValue = ISystemReward(SYSTEM_REWARD_ADDR).claimRewards(payable(address(this)), totalValue);
-    if (totalValue == 0) {
-      return;
-    }
-
-    uint256 totalWeight;
-    for (uint256 i; i<weights.length; ++i) {
-      totalWeight += weights[i];
-    }
-    if (totalWeight == 0) {
-      return;
-    }
-
-    uint256 value;
-    address valAddr;
-    uint256 index;
-
-    for (uint256 i; i<valAddrs.length; ++i) {
-      value = (totalValue * weights[i]) / totalWeight;
-      valAddr = valAddrs[i];
-      index = currentValidatorSetMap[valAddr];
-      if (index > 0) {
-        Validator storage validator = currentValidatorSet[index - 1];
-        if (validator.jailed) {
-          emit deprecatedFinalityRewardDeposit(valAddr, value);
-        } else {
-          totalInComing = totalInComing.add(value);
-          validator.incoming = validator.incoming.add(value);
-          emit finalityRewardDeposit(valAddr, value);
-        }
-      } else {
-        // get incoming from deprecated validator;
-        emit deprecatedFinalityRewardDeposit(valAddr, value);
-      }
-    }
+  /**
+   * @notice Return the index of the validator in `currentValidatorSet`(from 0 to `currentValidatorSet.length-1`)
+   */
+  function getCurrentValidatorIndex(address validator) public view returns (uint256) {
+    uint256 index = currentValidatorSetMap[validator];
+    require(index > 0, "only current validators");
 
+    // the actual index
+    return index - 1;
   }
 
-  function getWorkingValidatorCount() public view returns(uint256 workingValidatorCount) {
-    workingValidatorCount = getValidators().length;
+  function getMiningValidatorCount() public view returns(uint256 miningValidatorCount) {
+    miningValidatorCount = getValidators().length;
     uint256 _numOfCabinets = numOfCabinets > 0 ? numOfCabinets : INIT_NUM_OF_CABINETS;
-    if (workingValidatorCount > _numOfCabinets) {
-      workingValidatorCount = _numOfCabinets;
+    if (miningValidatorCount > _numOfCabinets) {
+      miningValidatorCount = _numOfCabinets;
     }
-    if (workingValidatorCount == 0) {
-      workingValidatorCount = 1;
+    if (miningValidatorCount == 0) {
+      miningValidatorCount = 1;
     }
   }
 
@@ -774,17 +604,6 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
   }
 
   /*********************** For Temporary Maintenance **************************/
-  /**
-   * @notice Return the index of the validator in `currentValidatorSet`(from 0 to `currentValidatorSet.length-1`)
-   */
-  function getCurrentValidatorIndex(address validator) public view returns (uint256) {
-    uint256 index = currentValidatorSetMap[validator];
-    require(index > 0, "only current validators");
-
-    // the actual index
-    return index - 1;
-  }
-
   /**
    * @notice Return whether the validator at index could enter maintenance
    */
@@ -833,8 +652,8 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
 
     // jailed validators are allowed to exit maintenance
     require(validatorExtraSet[index].isMaintaining, "not in maintenance");
-    uint256 workingValidatorCount = getWorkingValidatorCount();
-    _exitMaintenance(msg.sender, index, workingValidatorCount);
+    uint256 miningValidatorCount = getMiningValidatorCount();
+    _exitMaintenance(msg.sender, index, miningValidatorCount);
   }
 
   /*********************** Param update ********************************/
@@ -893,6 +712,172 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
   }
 
   /*********************** Internal Functions **************************/
+  function updateValidatorSet(Validator[] memory validatorSet, bytes[] memory voteAddrs) internal returns (uint32) {
+    {
+      // do verify.
+      if (validatorSet.length > MAX_NUM_OF_VALIDATORS) {
+        emit failReasonWithStr("the number of validators exceed the limit");
+        return ERROR_FAIL_CHECK_VALIDATORS;
+      }
+      for (uint i; i<validatorSet.length; ++i) {
+        for (uint j; j<i; ++j) {
+          if (validatorSet[i].consensusAddress == validatorSet[j].consensusAddress) {
+            emit failReasonWithStr("duplicate consensus address of validatorSet");
+            return ERROR_FAIL_CHECK_VALIDATORS;
+          }
+        }
+      }
+    }
+
+    // step 0: force all maintaining validators to exit `Temporary Maintenance`
+    // - 1. validators exit maintenance
+    // - 2. clear all maintainInfo
+    // - 3. get unjailed validators from validatorSet
+    Validator[] memory validatorSetTemp;
+    bytes[] memory voteAddrsTemp;
+    {
+      // get migrated validators
+      Validator[] memory bscValidatorSet = _tmpMigratedValidatorSet;
+      bytes[] memory bscVoteAddrs = _tmpMigratedVoteAddrs;
+      for (uint256 i; i < bscValidatorSet.length; ++i) {
+        bscValidatorSet[i].votingPower = bscValidatorSet[i].votingPower * 3; // amplify the voting power for BSC validators
+      }
+      (Validator[] memory mergedValidators, bytes[] memory mergedVoteAddrs) = _mergeValidatorSet(validatorSet, voteAddrs, bscValidatorSet, bscVoteAddrs);
+
+      (validatorSetTemp, voteAddrsTemp) = _forceMaintainingValidatorsExit(mergedValidators, mergedVoteAddrs);
+    }
+
+    {
+      //step 1: do calculate distribution, do not make it as an internal function for saving gas.
+      uint crossSize;
+      uint directSize;
+      uint validatorsNum = currentValidatorSet.length;
+      uint8[] memory isMigrated = new uint8[](validatorsNum);
+      for (uint i; i<validatorsNum; ++i) {
+        if (IStakeHub(STAKE_HUB_ADDR).consensusToOperator(currentValidatorSet[i].consensusAddress) != address(0)) {
+          isMigrated[i] = 1;
+          if (currentValidatorSet[i].incoming != 0) {
+            ++ directSize;
+          }
+        } else if (currentValidatorSet[i].incoming >= DUSTY_INCOMING) {
+          ++ crossSize;
+        } else if (currentValidatorSet[i].incoming != 0) {
+          ++ directSize;
+        }
+      }
+
+      //cross transfer
+      address[] memory crossAddrs = new address[](crossSize);
+      uint256[] memory crossAmounts = new uint256[](crossSize);
+      uint256[] memory crossIndexes = new uint256[](crossSize);
+      address[] memory crossRefundAddrs = new address[](crossSize);
+      uint256 crossTotal;
+      // direct transfer
+      address payable[] memory directAddrs = new address payable[](directSize);
+      uint256[] memory directAmounts = new uint256[](directSize);
+      crossSize = 0;
+      directSize = 0;
+      uint256 relayFee = ITokenHub(TOKEN_HUB_ADDR).getMiniRelayFee();
+      if (relayFee > DUSTY_INCOMING) {
+        emit failReasonWithStr("fee is larger than DUSTY_INCOMING");
+        return ERROR_RELAYFEE_TOO_LARGE;
+      }
+      for (uint i; i < validatorsNum; ++i) {
+        if (isMigrated[i] == 1) {
+          if (currentValidatorSet[i].incoming != 0) {
+            directAddrs[directSize] = payable(currentValidatorSet[i].consensusAddress);
+            directAmounts[directSize] = currentValidatorSet[i].incoming;
+            isMigrated[directSize] = 1; // directSize must be less than i. so we can use directSize as index
+            ++directSize;
+          }
+        } else if (currentValidatorSet[i].incoming >= DUSTY_INCOMING) {
+          crossAddrs[crossSize] = currentValidatorSet[i].BBCFeeAddress;
+          uint256 value = currentValidatorSet[i].incoming - currentValidatorSet[i].incoming % PRECISION;
+          crossAmounts[crossSize] = value.sub(relayFee);
+          crossRefundAddrs[crossSize] = currentValidatorSet[i].feeAddress;
+          crossIndexes[crossSize] = i;
+          crossTotal = crossTotal.add(value);
+          ++crossSize;
+        } else if (currentValidatorSet[i].incoming != 0) {
+          directAddrs[directSize] = currentValidatorSet[i].feeAddress;
+          directAmounts[directSize] = currentValidatorSet[i].incoming;
+          isMigrated[directSize] = 0;
+          ++directSize;
+        }
+      }
+
+      //step 2: do cross chain transfer
+      bool failCross = false;
+      if (crossTotal > 0) {
+        try ITokenHub(TOKEN_HUB_ADDR).batchTransferOutBNB{value : crossTotal}(crossAddrs, crossAmounts, crossRefundAddrs, uint64(block.timestamp + expireTimeSecondGap)) returns (bool success) {
+          if (success) {
+            emit batchTransfer(crossTotal);
+          } else {
+            emit batchTransferFailed(crossTotal, "batch transfer return false");
+          }
+        }catch Error(string memory reason) {
+          failCross = true;
+          emit batchTransferFailed(crossTotal, reason);
+        }catch (bytes memory lowLevelData) {
+          failCross = true;
+          emit batchTransferLowerFailed(crossTotal, lowLevelData);
+        }
+      }
+
+      if (failCross) {
+        for (uint i; i<crossIndexes.length; ++i) {
+          uint idx = crossIndexes[i];
+          bool success = currentValidatorSet[idx].feeAddress.send(currentValidatorSet[idx].incoming);
+          if (success) {
+            emit directTransfer(currentValidatorSet[idx].feeAddress, currentValidatorSet[idx].incoming);
+          } else {
+            emit directTransferFail(currentValidatorSet[idx].feeAddress, currentValidatorSet[idx].incoming);
+          }
+        }
+      }
+
+      // step 3: direct transfer
+      if (directAddrs.length > 0) {
+        for (uint i; i < directAddrs.length; ++i) {
+          if (isMigrated[i] == 1) {
+            IStakeHub(STAKE_HUB_ADDR).distributeReward{value : directAmounts[i]}(directAddrs[i]);
+          } else {
+            bool success = directAddrs[i].send(directAmounts[i]);
+            if (success) {
+              emit directTransfer(directAddrs[i], directAmounts[i]);
+            } else {
+              emit directTransferFail(directAddrs[i], directAmounts[i]);
+            }
+          }
+        }
+      }
+    }
+
+    for (uint i; i < currentValidatorSet.length; ++i) {
+      if (currentValidatorSet[i].incoming != 0) {
+          currentValidatorSet[i].incoming = 0;
+      }
+    }
+
+    // step 4: do dusk transfer
+    if (address(this).balance>0) {
+      emit systemTransfer(address(this).balance);
+      address(uint160(SYSTEM_REWARD_ADDR)).transfer(address(this).balance);
+    }
+
+    // step 5: do update validator set state
+    totalInComing = 0;
+    numOfJailed = 0;
+    if (validatorSetTemp.length > 0) {
+      doUpdateState(validatorSetTemp, voteAddrsTemp);
+    }
+
+    // step 6: clean slash contract
+    ISlashIndicator(SLASH_CONTRACT_ADDR).clean();
+    emit validatorSetUpdated();
+    return CODE_OK;
+  }
+
   function doUpdateState(Validator[] memory newValidatorSet, bytes[] memory newVoteAddrs) private {
     uint n = currentValidatorSet.length;
     uint m = newValidatorSet.length;
@@ -962,6 +947,23 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
     }
   }
 
+  /**
+   * @dev With each epoch, there will be a partial rotation between cabinets and candidates. Rotation is determined by this function
+   */
+  function shuffle(address[] memory validators, bytes[] memory voteAddrs, uint256 epochNumber, uint startIdx, uint offset, uint limit, uint modNumber) internal pure {
+    for (uint i; i<limit; ++i) {
+      uint random = uint(keccak256(abi.encodePacked(epochNumber, startIdx+i))) % modNumber;
+      if ( (startIdx+i) != (offset+random) ) {
+        address tmpAddr = validators[startIdx+i];
+        bytes memory tmpBLS = voteAddrs[startIdx+i];
+        validators[startIdx+i] = validators[offset+random];
+        validators[offset+random] = tmpAddr;
+        voteAddrs[startIdx+i] = voteAddrs[offset+random];
+        voteAddrs[offset+random] = tmpBLS;
+      }
+    }
+  }
+
   /**
    * @dev Check if two validators are the same
    *
@@ -1124,9 +1126,9 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
 
     // 1. validators exit maintenance
     uint256 i;
-    // caution: it must calculate workingValidatorCount before _exitMaintenance loop
-    // because the workingValidatorCount will be changed in _exitMaintenance
-    uint256 workingValidatorCount = getWorkingValidatorCount();
+    // caution: it must calculate miningValidatorCount before _exitMaintenance loop
+    // because the miningValidatorCount will be changed in _exitMaintenance
+    uint256 miningValidatorCount = getMiningValidatorCount();
     // caution: it must loop from the endIndex to startIndex in currentValidatorSet
     // because the validators order in currentValidatorSet may be changed by _felony(validator)
     for (uint index = currentValidatorSet.length; index > 0; --index) {
@@ -1139,7 +1141,7 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
       validator = currentValidatorSet[i].consensusAddress;
 
       // exit maintenance
-      isFelony = _exitMaintenance(validator, i, workingValidatorCount);
+      isFelony = _exitMaintenance(validator, i, miningValidatorCount);
       if (!isFelony || numOfFelony >= _validatorSet.length - 1) {
         continue;
       }
@@ -1176,8 +1178,8 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
     emit validatorEnterMaintenance(validator);
   }
 
-  function _exitMaintenance(address validator, uint index, uint256 workingValidatorCount) private returns (bool isFelony){
-    if (maintainSlashScale == 0 || workingValidatorCount == 0 || numOfMaintaining == 0) {
+  function _exitMaintenance(address validator, uint index, uint256 miningValidatorCount) private returns (bool isFelony){
+    if (maintainSlashScale == 0 || miningValidatorCount == 0 || numOfMaintaining == 0) {
       // should not happen, still protect
       return false;
     }
@@ -1189,7 +1191,7 @@ contract BSCValidatorSet is IBSCValidatorSet, System, IParamSubscriber, IApplica
     uint256 slashCount =
       block.number
         .sub(validatorExtraSet[index].enterMaintenanceHeight)
-        .div(workingValidatorCount)
+        .div(miningValidatorCount)
         .div(maintainSlashScale);
 
     // step 2: clear maintaining info of the validator