diff --git a/consensus/XDPoS/engines/engine_v2/timeout.go b/consensus/XDPoS/engines/engine_v2/timeout.go
index 61f8e52ca0..15f030cdd9 100644
--- a/consensus/XDPoS/engines/engine_v2/timeout.go
+++ b/consensus/XDPoS/engines/engine_v2/timeout.go
@@ -108,11 +108,11 @@ func (x *XDPoS_v2) onTimeoutPoolThresholdReached(blockChainReader consensus.Chai
 	// Process TC
 	err := x.processTC(blockChainReader, timeoutCert)
 	if err != nil {
-		log.Error("[onTimeoutPoolThresholdReached] Error while processing TC in the Timeout handler after reaching pool threshold", "TcRound", timeoutCert.Round, "NumberOfTcSig", len(timeoutCert.Signatures), "GapNumber", gapNumber, "Error", err)
+		log.Error("[onTimeoutPoolThresholdReached] Fail to process TC", "TcRound", timeoutCert.Round, "NumberOfTcSig", len(timeoutCert.Signatures), "GapNumber", gapNumber, "Error", err)
 		return err
 	}
 
-	log.Info("[onTimeoutPoolThresholdReached] Successfully processed the timeout message and produced TC!", "TcRound", timeoutCert.Round, "NumberOfTcSig", len(timeoutCert.Signatures))
+	log.Info("[onTimeoutPoolThresholdReached] process TC successfully", "TcRound", timeoutCert.Round, "NumberOfTcSig", len(timeoutCert.Signatures))
 	return nil
 }
 
diff --git a/consensus/XDPoS/engines/engine_v2/verifyHeader.go b/consensus/XDPoS/engines/engine_v2/verifyHeader.go
index adbefd3b28..12799c56e9 100644
--- a/consensus/XDPoS/engines/engine_v2/verifyHeader.go
+++ b/consensus/XDPoS/engines/engine_v2/verifyHeader.go
@@ -104,7 +104,7 @@ func (x *XDPoS_v2) verifyHeader(chain consensus.ChainReader, header *types.Heade
 	if header.MixDigest != (common.Hash{}) {
 		return utils.ErrInvalidMixDigest
 	}
-	// Ensure that the block doesn't contain any uncles which are meaningless in XDPoS_v1
+	// Ensure that the block doesn't contain any uncles which are meaningless in XDPoS_v2.
 	if header.UncleHash != utils.UncleHash {
 		return utils.ErrInvalidUncleHash
 	}
diff --git a/consensus/XDPoS/utils/pool.go b/consensus/XDPoS/utils/pool.go
index 2e3ea31b4f..57f6b93a0f 100644
--- a/consensus/XDPoS/utils/pool.go
+++ b/consensus/XDPoS/utils/pool.go
@@ -39,6 +39,8 @@ func (p *Pool) Get() map[string]map[common.Hash]PoolObj {
 	return dataCopy
 }
 
+// Add adds the object to the pool, returns the number of items
+// and the map of objects under the same pool key
 func (p *Pool) Add(obj PoolObj) (int, map[common.Hash]PoolObj) {
 	p.lock.Lock()
 	defer p.lock.Unlock()
diff --git a/params/protocol_params.go b/params/protocol_params.go
index b119c98a08..364b6efd33 100644
--- a/params/protocol_params.go
+++ b/params/protocol_params.go
@@ -19,8 +19,8 @@ package params
 import "math/big"
 
 var (
-	TargetGasLimit uint64 = XDCGenesisGasLimit // The artificial target
-	V2TestsGasLimit uint64 = 1200000000        // The gas limit used in the v2 consensus tests
+	TargetGasLimit  uint64 = XDCGenesisGasLimit // The artificial target
+	V2TestsGasLimit uint64 = 1200000000         // The gas limit used in the v2 consensus tests
 )
 
 const (
@@ -39,7 +39,7 @@ const (
 	TxGasContractCreation uint64 = 53000 // Per transaction that creates a contract. NOTE: Not payable on data of calls between transactions.
 	TxDataZeroGas         uint64 = 4     // Per byte of data attached to a transaction that equals zero. NOTE: Not payable on data of calls between transactions.
 	QuadCoeffDiv          uint64 = 512   // Divisor for the quadratic particle of the memory cost equation.
-	SstoreSetGas          uint64 = 20000 // Once per SLOAD operation.
+	SstoreSetGas          uint64 = 20000 // Once per SSTORE operation.
 	LogDataGas            uint64 = 8     // Per byte in a LOG* operation's data.
 	CallStipend           uint64 = 2300  // Free gas given at beginning of call.
 
@@ -50,7 +50,7 @@ const (
 	SstoreResetGas   uint64 = 5000  // Once per SSTORE operation if the zeroness changes from zero.
 	SstoreClearGas   uint64 = 5000  // Once per SSTORE operation if the zeroness doesn't change.
 	SstoreRefundGas  uint64 = 15000 // Once per SSTORE operation if the zeroness changes to zero.
-	JumpdestGas      uint64 = 1     // Refunded gas, once per SSTORE operation if the zeroness changes to zero.
+	JumpdestGas      uint64 = 1     // Once per JUMPDEST operation.
 	EpochDuration    uint64 = 30000 // Duration between proof-of-work epochs.
 	CallGas          uint64 = 40    // Once per CALL operation & message call transaction.
 	CreateDataGas    uint64 = 200   //