bound mempool memory usage (#3248)

* bound mempool memory usage

Closes #3079

* rename SizeBytes to TxsTotalBytes

and other small fixes after Zarko's review

* rename MaxBytes to MaxTxsTotalBytes

* make ErrMempoolIsFull more informative

* expose mempool's txs_total_bytes via RPC

* test full response

* fixes after Ethan's review

* config: rename mempool.size to mempool.max_txs

https://github.com/tendermint/tendermint/pull/3248#discussion_r254034004

* test more cases

https://github.com/tendermint/tendermint/pull/3248#discussion_r254036532

* simplify test

* Revert "config: rename mempool.size to mempool.max_txs"

This reverts commit 39bfa36961.

* rename count back to n_txs

to make a change non-breaking

* rename max_txs_total_bytes to max_txs_bytes

* format code

* fix TestWALPeriodicSync

The test was sometimes failing due to processFlushTicks being called too
early. The solution is to call wal#Start later in the test.

* Apply suggestions from code review

CHANGELOG_PENDING.md

@@ -18,6 +18,9 @@ Special thanks to external contributors on this release:
 * P2P Protocol
 
 ### FEATURES:
+- [mempool] \#3079 bound mempool memory usage (`mempool.max_txs_bytes` is set to 1GB by default; see config.toml)
+  mempool's current `txs_total_bytes` is exposed via `total_bytes` field in
+  `/num_unconfirmed_txs` and `/unconfirmed_txs` RPC endpoints.
 
 ### IMPROVEMENTS:
 

config/config.go

@@ -530,12 +530,13 @@ func DefaultFuzzConnConfig() *FuzzConnConfig {
 
 // MempoolConfig defines the configuration options for the Tendermint mempool
 type MempoolConfig struct {
-	RootDir   string `mapstructure:"home"`
-	Recheck   bool   `mapstructure:"recheck"`
-	Broadcast bool   `mapstructure:"broadcast"`
-	WalPath   string `mapstructure:"wal_dir"`
-	Size      int    `mapstructure:"size"`
-	CacheSize int    `mapstructure:"cache_size"`
+	RootDir     string `mapstructure:"home"`
+	Recheck     bool   `mapstructure:"recheck"`
+	Broadcast   bool   `mapstructure:"broadcast"`
+	WalPath     string `mapstructure:"wal_dir"`
+	Size        int    `mapstructure:"size"`
+	MaxTxsBytes int64  `mapstructure:"max_txs_bytes"`
+	CacheSize   int    `mapstructure:"cache_size"`
 }
 
 // DefaultMempoolConfig returns a default configuration for the Tendermint mempool
@@ -544,10 +545,11 @@ func DefaultMempoolConfig() *MempoolConfig {
 		Recheck:   true,
 		Broadcast: true,
 		WalPath:   "",
-		// Each signature verification takes .5ms, size reduced until we implement
+		// Each signature verification takes .5ms, Size reduced until we implement
 		// ABCI Recheck
-		Size:      5000,
-		CacheSize: 10000,
+		Size:        5000,
+		MaxTxsBytes: 1024 * 1024 * 1024, // 1GB
+		CacheSize:   10000,
 	}
 }
 
@@ -574,6 +576,9 @@ func (cfg *MempoolConfig) ValidateBasic() error {
 	if cfg.Size < 0 {
 		return errors.New("size can't be negative")
 	}
+	if cfg.MaxTxsBytes < 0 {
+		return errors.New("max_txs_bytes can't be negative")
+	}
 	if cfg.CacheSize < 0 {
 		return errors.New("cache_size can't be negative")
 	}

config/toml.go

@@ -237,10 +237,15 @@ recheck = {{ .Mempool.Recheck }}
 broadcast = {{ .Mempool.Broadcast }}
 wal_dir = "{{ js .Mempool.WalPath }}"
 
-# size of the mempool
+# Maximum number of transactions in the mempool
 size = {{ .Mempool.Size }}
 
-# size of the cache (used to filter transactions we saw earlier)
+# Limit the total size of all txs in the mempool.
+# This only accounts for raw transactions (e.g. given 1MB transactions and
+# max_txs_bytes=5MB, mempool will only accept 5 transactions).
+max_txs_bytes = {{ .Mempool.MaxTxsBytes }}
+
+# Size of the cache (used to filter transactions we saw earlier) in transactions
 cache_size = {{ .Mempool.CacheSize }}
 
 ##### consensus configuration options #####

docs/tendermint-core/configuration.md

@@ -183,10 +183,15 @@ recheck = true
 broadcast = true
 wal_dir = ""
 
-# size of the mempool
+# Maximum number of transactions in the mempool
 size = 5000
 
-# size of the cache (used to filter transactions we saw earlier)
+# Limit the total size of all txs in the mempool.
+# This only accounts for raw transactions (e.g. given 1MB transactions and
+# max_txs_bytes=5MB, mempool will only accept 5 transactions).
+max_txs_bytes = 1073741824
+
+# Size of the cache (used to filter transactions we saw earlier) in transactions
 cache_size = 10000
 
 ##### consensus configuration options #####

mempool/mempool.go

@@ -63,13 +63,26 @@ var (
 	// ErrTxInCache is returned to the client if we saw tx earlier
 	ErrTxInCache = errors.New("Tx already exists in cache")
 
-	// ErrMempoolIsFull means Tendermint & an application can't handle that much load
-	ErrMempoolIsFull = errors.New("Mempool is full")
-
 	// ErrTxTooLarge means the tx is too big to be sent in a message to other peers
 	ErrTxTooLarge = fmt.Errorf("Tx too large. Max size is %d", maxTxSize)
 )
 
+// ErrMempoolIsFull means Tendermint & an application can't handle that much load
+type ErrMempoolIsFull struct {
+	numTxs int
+	maxTxs int
+
+	txsBytes    int64
+	maxTxsBytes int64
+}
+
+func (e ErrMempoolIsFull) Error() string {
+	return fmt.Sprintf(
+		"Mempool is full: number of txs %d (max: %d), total txs bytes %d (max: %d)",
+		e.numTxs, e.maxTxs,
+		e.txsBytes, e.maxTxsBytes)
+}
+
 // ErrPreCheck is returned when tx is too big
 type ErrPreCheck struct {
 	Reason error
@@ -147,6 +160,9 @@ type Mempool struct {
 	preCheck             PreCheckFunc
 	postCheck            PostCheckFunc
 
+	// Atomic integers
+	txsBytes int64 // see TxsBytes
+
 	// Keep a cache of already-seen txs.
 	// This reduces the pressure on the proxyApp.
 	cache txCache
@@ -265,8 +281,13 @@ func (mem *Mempool) Size() int {
 	return mem.txs.Len()
 }
 
-// Flushes the mempool connection to ensure async resCb calls are done e.g.
-// from CheckTx.
+// TxsBytes returns the total size of all txs in the mempool.
+func (mem *Mempool) TxsBytes() int64 {
+	return atomic.LoadInt64(&mem.txsBytes)
+}
+
+// FlushAppConn flushes the mempool connection to ensure async resCb calls are
+// done e.g. from CheckTx.
 func (mem *Mempool) FlushAppConn() error {
 	return mem.proxyAppConn.FlushSync()
 }
@@ -282,6 +303,8 @@ func (mem *Mempool) Flush() {
 		mem.txs.Remove(e)
 		e.DetachPrev()
 	}
+
+	_ = atomic.SwapInt64(&mem.txsBytes, 0)
 }
 
 // TxsFront returns the first transaction in the ordered list for peer
@@ -308,8 +331,15 @@ func (mem *Mempool) CheckTx(tx types.Tx, cb func(*abci.Response)) (err error) {
 	// use defer to unlock mutex because application (*local client*) might panic
 	defer mem.proxyMtx.Unlock()
 
-	if mem.Size() >= mem.config.Size {
-		return ErrMempoolIsFull
+	var (
+		memSize  = mem.Size()
+		txsBytes = mem.TxsBytes()
+	)
+	if memSize >= mem.config.Size ||
+		int64(len(tx))+txsBytes > mem.config.MaxTxsBytes {
+		return ErrMempoolIsFull{
+			memSize, mem.config.Size,
+			txsBytes, mem.config.MaxTxsBytes}
 	}
 
 	// The size of the corresponding amino-encoded TxMessage
@@ -383,6 +413,7 @@ func (mem *Mempool) resCbNormal(req *abci.Request, res *abci.Response) {
 				tx:        tx,
 			}
 			mem.txs.PushBack(memTx)
+			atomic.AddInt64(&mem.txsBytes, int64(len(tx)))
 			mem.logger.Info("Added good transaction",
 				"tx", TxID(tx),
 				"res", r,
@@ -424,6 +455,7 @@ func (mem *Mempool) resCbRecheck(req *abci.Request, res *abci.Response) {
 			// Tx became invalidated due to newly committed block.
 			mem.logger.Info("Tx is no longer valid", "tx", TxID(tx), "res", r, "err", postCheckErr)
 			mem.txs.Remove(mem.recheckCursor)
+			atomic.AddInt64(&mem.txsBytes, int64(-len(tx)))
 			mem.recheckCursor.DetachPrev()
 
 			// remove from cache (it might be good later)
@@ -597,6 +629,7 @@ func (mem *Mempool) removeTxs(txs types.Txs) []types.Tx {
 		if _, ok := txsMap[string(memTx.tx)]; ok {
 			// remove from clist
 			mem.txs.Remove(e)
+			atomic.AddInt64(&mem.txsBytes, int64(-len(memTx.tx)))
 			e.DetachPrev()
 
 			// NOTE: we don't remove committed txs from the cache.

mempool/mempool_test.go

@@ -30,8 +30,10 @@ import (
 type cleanupFunc func()
 
 func newMempoolWithApp(cc proxy.ClientCreator) (*Mempool, cleanupFunc) {
-	config := cfg.ResetTestRoot("mempool_test")
+	return newMempoolWithAppAndConfig(cc, cfg.ResetTestRoot("mempool_test"))
+}
 
+func newMempoolWithAppAndConfig(cc proxy.ClientCreator, config *cfg.Config) (*Mempool, cleanupFunc) {
 	appConnMem, _ := cc.NewABCIClient()
 	appConnMem.SetLogger(log.TestingLogger().With("module", "abci-client", "connection", "mempool"))
 	err := appConnMem.Start()
@@ -462,6 +464,72 @@ func TestMempoolMaxMsgSize(t *testing.T) {
 
 }
 
+func TestMempoolTxsBytes(t *testing.T) {
+	app := kvstore.NewKVStoreApplication()
+	cc := proxy.NewLocalClientCreator(app)
+	config := cfg.ResetTestRoot("mempool_test")
+	config.Mempool.MaxTxsBytes = 10
+	mempool, cleanup := newMempoolWithAppAndConfig(cc, config)
+	defer cleanup()
+
+	// 1. zero by default
+	assert.EqualValues(t, 0, mempool.TxsBytes())
+
+	// 2. len(tx) after CheckTx
+	err := mempool.CheckTx([]byte{0x01}, nil)
+	require.NoError(t, err)
+	assert.EqualValues(t, 1, mempool.TxsBytes())
+
+	// 3. zero again after tx is removed by Update
+	mempool.Update(1, []types.Tx{[]byte{0x01}}, nil, nil)
+	assert.EqualValues(t, 0, mempool.TxsBytes())
+
+	// 4. zero after Flush
+	err = mempool.CheckTx([]byte{0x02, 0x03}, nil)
+	require.NoError(t, err)
+	assert.EqualValues(t, 2, mempool.TxsBytes())
+
+	mempool.Flush()
+	assert.EqualValues(t, 0, mempool.TxsBytes())
+
+	// 5. ErrMempoolIsFull is returned when/if MaxTxsBytes limit is reached.
+	err = mempool.CheckTx([]byte{0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04}, nil)
+	require.NoError(t, err)
+	err = mempool.CheckTx([]byte{0x05}, nil)
+	if assert.Error(t, err) {
+		assert.IsType(t, ErrMempoolIsFull{}, err)
+	}
+
+	// 6. zero after tx is rechecked and removed due to not being valid anymore
+	app2 := counter.NewCounterApplication(true)
+	cc = proxy.NewLocalClientCreator(app2)
+	mempool, cleanup = newMempoolWithApp(cc)
+	defer cleanup()
+
+	txBytes := make([]byte, 8)
+	binary.BigEndian.PutUint64(txBytes, uint64(0))
+
+	err = mempool.CheckTx(txBytes, nil)
+	require.NoError(t, err)
+	assert.EqualValues(t, 8, mempool.TxsBytes())
+
+	appConnCon, _ := cc.NewABCIClient()
+	appConnCon.SetLogger(log.TestingLogger().With("module", "abci-client", "connection", "consensus"))
+	err = appConnCon.Start()
+	require.Nil(t, err)
+	defer appConnCon.Stop()
+	res, err := appConnCon.DeliverTxSync(txBytes)
+	require.NoError(t, err)
+	require.EqualValues(t, 0, res.Code)
+	res2, err := appConnCon.CommitSync()
+	require.NoError(t, err)
+	require.NotEmpty(t, res2.Data)
+
+	// Pretend like we committed nothing so txBytes gets rechecked and removed.
+	mempool.Update(1, []types.Tx{}, nil, nil)
+	assert.EqualValues(t, 0, mempool.TxsBytes())
+}
+
 func checksumIt(data []byte) string {
 	h := sha256.New()
 	h.Write(data)

rpc/client/rpc_test.go

@@ -290,9 +290,13 @@ func TestUnconfirmedTxs(t *testing.T) {
 	for i, c := range GetClients() {
 		mc, ok := c.(client.MempoolClient)
 		require.True(t, ok, "%d", i)
-		txs, err := mc.UnconfirmedTxs(1)
+		res, err := mc.UnconfirmedTxs(1)
 		require.Nil(t, err, "%d: %+v", i, err)
-		assert.Exactly(t, types.Txs{tx}, types.Txs(txs.Txs))
+
+		assert.Equal(t, 1, res.Count)
+		assert.Equal(t, 1, res.Total)
+		assert.Equal(t, mempool.TxsBytes(), res.TotalBytes)
+		assert.Exactly(t, types.Txs{tx}, types.Txs(res.Txs))
 	}
 
 	mempool.Flush()
@@ -311,7 +315,9 @@ func TestNumUnconfirmedTxs(t *testing.T) {
 		res, err := mc.NumUnconfirmedTxs()
 		require.Nil(t, err, "%d: %+v", i, err)
 
-		assert.Equal(t, mempoolSize, res.N)
+		assert.Equal(t, mempoolSize, res.Count)
+		assert.Equal(t, mempoolSize, res.Total)
+		assert.Equal(t, mempool.TxsBytes(), res.TotalBytes)
 	}
 
 	mempool.Flush()

rpc/core/mempool.go

@@ -248,27 +248,32 @@ func BroadcastTxCommit(tx types.Tx) (*ctypes.ResultBroadcastTxCommit, error) {
 //
 // ```json
 // {
-//   "error": "",
-//   "result": {
-//     "txs": [],
-//     "n_txs": "0"
-//   },
-//   "id": "",
-//   "jsonrpc": "2.0"
-// }
+//   "result" : {
+//       "txs" : [],
+//       "total_bytes" : "0",
+//       "n_txs" : "0",
+//       "total" : "0"
+//     },
+//     "jsonrpc" : "2.0",
+//     "id" : ""
+//   }
+// ```
 //
 // ### Query Parameters
 //
 // | Parameter | Type | Default | Required | Description                          |
 // |-----------+------+---------+----------+--------------------------------------|
 // | limit     | int  | 30      | false    | Maximum number of entries (max: 100) |
-// ```
 func UnconfirmedTxs(limit int) (*ctypes.ResultUnconfirmedTxs, error) {
 	// reuse per_page validator
 	limit = validatePerPage(limit)
 
 	txs := mempool.ReapMaxTxs(limit)
-	return &ctypes.ResultUnconfirmedTxs{N: len(txs), Txs: txs}, nil
+	return &ctypes.ResultUnconfirmedTxs{
+		Count:      len(txs),
+		Total:      mempool.Size(),
+		TotalBytes: mempool.TxsBytes(),
+		Txs:        txs}, nil
 }
 
 // Get number of unconfirmed transactions.
@@ -291,15 +296,19 @@ func UnconfirmedTxs(limit int) (*ctypes.ResultUnconfirmedTxs, error) {
 //
 // ```json
 // {
-//   "error": "",
-//   "result": {
-//     "txs": null,
-//     "n_txs": "0"
-//   },
-//   "id": "",
-//   "jsonrpc": "2.0"
+//   "jsonrpc" : "2.0",
+//   "id" : "",
+//   "result" : {
+//     "n_txs" : "0",
+//     "total_bytes" : "0",
+//     "txs" : null,
+//     "total" : "0"
+//   }
 // }
 // ```
 func NumUnconfirmedTxs() (*ctypes.ResultUnconfirmedTxs, error) {
-	return &ctypes.ResultUnconfirmedTxs{N: mempool.Size()}, nil
+	return &ctypes.ResultUnconfirmedTxs{
+		Count:      mempool.Size(),
+		Total:      mempool.Size(),
+		TotalBytes: mempool.TxsBytes()}, nil
 }

rpc/core/types/responses.go

@@ -178,8 +178,10 @@ type ResultTxSearch struct {
 
 // List of mempool txs
 type ResultUnconfirmedTxs struct {
-	N   int        `json:"n_txs"`
-	Txs []types.Tx `json:"txs"`
+	Count      int        `json:"n_txs"`
+	Total      int        `json:"total"`
+	TotalBytes int64      `json:"total_bytes"`
+	Txs        []types.Tx `json:"txs"`
 }
 
 // Info abci msg