separate limit for pending tx

config/config.go

@@ -799,6 +799,12 @@ type MempoolConfig struct {
 	// blacklist the peer.
 	CheckTxErrorBlacklistEnabled bool `mapstructure:"check-tx-error-blacklist-enabled"`
 	CheckTxErrorThreshold        int  `mapstructure:"check-tx-error-threshold"`
+
+	// Maximum number of transactions in the pending set
+	PendingSize int `mapstructure:"pending-size"`
+
+	// Limit the total size of all txs in the pending set.
+	MaxPendingTxsBytes int64 `mapstructure:"max-pending-txs-bytes"`
 }
 
 // DefaultMempoolConfig returns a default configuration for the Tendermint mempool.
@@ -816,6 +822,8 @@ func DefaultMempoolConfig() *MempoolConfig {
 		TxNotifyThreshold:            0,
 		CheckTxErrorBlacklistEnabled: false,
 		CheckTxErrorThreshold:        0,
+		PendingSize:                  5000,
+		MaxPendingTxsBytes:           1024 * 1024 * 1024, // 1GB
 	}
 }
 

config/toml.go

@@ -405,6 +405,10 @@ check-tx-error-blacklist-enabled = {{ .Mempool.CheckTxErrorBlacklistEnabled }}
 
 check-tx-error-threshold = {{ .Mempool.CheckTxErrorThreshold }}
 
+pending-size = {{ .Mempool.PendingSize }}
+
+max-pending-txs-bytes = {{ .Mempool.MaxPendingTxsBytes }}
+
 #######################################################
 ###         State Sync Configuration Options        ###
 #######################################################

internal/mempool/mempool.go

@@ -43,6 +43,9 @@ type TxMempool struct {
 	// sizeBytes defines the total size of the mempool (sum of all tx bytes)
 	sizeBytes int64
 
+	// pendingSizeBytes defines the total size of the pending set (sum of all tx bytes)
+	pendingSizeBytes int64
+
 	// cache defines a fixed-size cache of already seen transactions as this
 	// reduces pressure on the proxyApp.
 	cache TxCache
@@ -177,9 +180,11 @@ func (txmp *TxMempool) Unlock() {
 // Size returns the number of valid transactions in the mempool. It is
 // thread-safe.
 func (txmp *TxMempool) Size() int {
-	txSize := txmp.txStore.Size()
-	pendingSize := txmp.pendingTxs.Size()
-	return txSize + pendingSize
+	return txmp.SizeWithoutPending() + txmp.PendingSize()
+}
+
+func (txmp *TxMempool) SizeWithoutPending() int {
+	return txmp.txStore.Size()
 }
 
 // PendingSize returns the number of pending transactions in the mempool.
@@ -193,6 +198,10 @@ func (txmp *TxMempool) SizeBytes() int64 {
 	return atomic.LoadInt64(&txmp.sizeBytes)
 }
 
+func (txmp *TxMempool) PendingSizeBytes() int64 {
+	return atomic.LoadInt64(&txmp.pendingSizeBytes)
+}
+
 // FlushAppConn executes FlushSync on the mempool's proxyAppConn.
 //
 // NOTE: The caller must obtain a write-lock prior to execution.
@@ -326,6 +335,11 @@ func (txmp *TxMempool) CheckTx(
 			if res.Checker == nil {
 				return errors.New("no checker available for pending transaction")
 			}
+			if err := txmp.canAddPendingTx(wtx); err != nil {
+				// TODO: eviction strategy for pending transactions
+				return err
+			}
+			atomic.AddInt64(&txmp.pendingSizeBytes, int64(wtx.Size()))
 			txmp.pendingTxs.Insert(wtx, res, txInfo)
 		}
 	}
@@ -410,7 +424,7 @@ func (txmp *TxMempool) ReapMaxBytesMaxGas(maxBytes, maxGas int64) types.Txs {
 	)
 
 	var txs []types.Tx
-	if uint64(txmp.Size()) < txmp.config.TxNotifyThreshold {
+	if uint64(txmp.SizeWithoutPending()) < txmp.config.TxNotifyThreshold {
 		// do not reap anything if threshold is not met
 		return txs
 	}
@@ -522,7 +536,7 @@ func (txmp *TxMempool) Update(
 		}
 	}
 
-	txmp.metrics.Size.Set(float64(txmp.Size()))
+	txmp.metrics.Size.Set(float64(txmp.SizeWithoutPending()))
 	txmp.metrics.PendingSize.Set(float64(txmp.PendingSize()))
 	return nil
 }
@@ -640,7 +654,7 @@ func (txmp *TxMempool) addNewTransaction(wtx *WrappedTx, res *abci.ResponseCheck
 	}
 
 	txmp.metrics.TxSizeBytes.Observe(float64(wtx.Size()))
-	txmp.metrics.Size.Set(float64(txmp.Size()))
+	txmp.metrics.Size.Set(float64(txmp.SizeWithoutPending()))
 	txmp.metrics.PendingSize.Set(float64(txmp.PendingSize()))
 
 	if txmp.insertTx(wtx) {
@@ -649,7 +663,7 @@ func (txmp *TxMempool) addNewTransaction(wtx *WrappedTx, res *abci.ResponseCheck
 			"priority", wtx.priority,
 			"tx", fmt.Sprintf("%X", wtx.tx.Hash()),
 			"height", txmp.height,
-			"num_txs", txmp.Size(),
+			"num_txs", txmp.SizeWithoutPending(),
 		)
 		txmp.notifyTxsAvailable()
 	}
@@ -745,12 +759,12 @@ func (txmp *TxMempool) handleRecheckResult(tx types.Tx, res *abci.ResponseCheckT
 	if txmp.recheckCursor == nil {
 		txmp.logger.Debug("finished rechecking transactions")
 
-		if txmp.Size() > 0 {
+		if txmp.SizeWithoutPending() > 0 {
 			txmp.notifyTxsAvailable()
 		}
 	}
 
-	txmp.metrics.Size.Set(float64(txmp.Size()))
+	txmp.metrics.Size.Set(float64(txmp.SizeWithoutPending()))
 	txmp.metrics.PendingSize.Set(float64(txmp.PendingSize()))
 }
 
@@ -803,7 +817,7 @@ func (txmp *TxMempool) updateReCheckTxs(ctx context.Context) {
 // the transaction can be inserted into the mempool.
 func (txmp *TxMempool) canAddTx(wtx *WrappedTx) error {
 	var (
-		numTxs    = txmp.Size()
+		numTxs    = txmp.SizeWithoutPending()
 		sizeBytes = txmp.SizeBytes()
 	)
 
@@ -819,6 +833,24 @@ func (txmp *TxMempool) canAddTx(wtx *WrappedTx) error {
 	return nil
 }
 
+func (txmp *TxMempool) canAddPendingTx(wtx *WrappedTx) error {
+	var (
+		numTxs    = txmp.PendingSize()
+		sizeBytes = txmp.PendingSizeBytes()
+	)
+
+	if numTxs >= txmp.config.PendingSize || int64(wtx.Size())+sizeBytes > txmp.config.MaxPendingTxsBytes {
+		return types.ErrMempoolPendingIsFull{
+			NumTxs:      numTxs,
+			MaxTxs:      txmp.config.PendingSize,
+			TxsBytes:    sizeBytes,
+			MaxTxsBytes: txmp.config.MaxPendingTxsBytes,
+		}
+	}
+
+	return nil
+}
+
 func (txmp *TxMempool) insertTx(wtx *WrappedTx) bool {
 	if txmp.isInMempool(wtx.tx) {
 		return false
@@ -936,12 +968,13 @@ func (txmp *TxMempool) purgeExpiredTxs(blockHeight int64) {
 
 	// remove pending txs that have expired
 	txmp.pendingTxs.PurgeExpired(txmp.config.TTLNumBlocks, blockHeight, txmp.config.TTLDuration, now, func(wtx *WrappedTx) {
+		atomic.AddInt64(&txmp.pendingSizeBytes, int64(-wtx.Size()))
 		txmp.expire(blockHeight, wtx)
 	})
 }
 
 func (txmp *TxMempool) notifyTxsAvailable() {
-	if txmp.Size() == 0 {
+	if txmp.SizeWithoutPending() == 0 {
 		return
 	}
 
@@ -980,12 +1013,14 @@ func (txmp *TxMempool) AppendCheckTxErr(existingLogs string, log string) string
 func (txmp *TxMempool) handlePendingTransactions() {
 	accepted, rejected := txmp.pendingTxs.EvaluatePendingTransactions()
 	for _, tx := range accepted {
+		atomic.AddInt64(&txmp.pendingSizeBytes, int64(-tx.tx.Size()))
 		if err := txmp.addNewTransaction(tx.tx, tx.checkTxResponse.ResponseCheckTx, tx.txInfo); err != nil {
 			txmp.logger.Error(fmt.Sprintf("error adding pending transaction: %s", err))
 		}
 	}
-	if !txmp.config.KeepInvalidTxsInCache {
-		for _, tx := range rejected {
+	for _, tx := range rejected {
+		atomic.AddInt64(&txmp.pendingSizeBytes, int64(-tx.tx.Size()))
+		if !txmp.config.KeepInvalidTxsInCache {
 			tx.tx.removeHandler(true)
 		}
 	}

types/mempool.go

@@ -4,6 +4,7 @@ import (
 	"crypto/sha256"
 	"errors"
 	"fmt"
+
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
 )
 
@@ -84,6 +85,25 @@ func (e ErrMempoolIsFull) Error() string {
 	)
 }
 
+// ErrMempoolPendingIsFull defines an error where there are too many pending transactions
+// not processed yet
+type ErrMempoolPendingIsFull struct {
+	NumTxs      int
+	MaxTxs      int
+	TxsBytes    int64
+	MaxTxsBytes int64
+}
+
+func (e ErrMempoolPendingIsFull) Error() string {
+	return fmt.Sprintf(
+		"mempool pending set is full: number of txs %d (max: %d), total txs bytes %d (max: %d)",
+		e.NumTxs,
+		e.MaxTxs,
+		e.TxsBytes,
+		e.MaxTxsBytes,
+	)
+}
+
 // ErrPreCheck defines an error where a transaction fails a pre-check.
 type ErrPreCheck struct {
 	Reason error