From 924065e19d08cc7e6af0b3a5b5b1ef3785b79bd4 Mon Sep 17 00:00:00 2001
From: Felix Lange <fjl@users.noreply.github.com>
Date: Tue, 23 Jan 2018 11:05:30 +0100
Subject: [PATCH] consensus/ethash: improve cache/dataset handling (#15864)
* consensus/ethash: add maxEpoch constant
* consensus/ethash: improve cache/dataset handling
There are two fixes in this commit:
Unmap the memory through a finalizer like the libethash wrapper did. The
release logic was incorrect and freed the memory while it was being
used, leading to crashes like in #14495 or #14943.
Track caches and datasets using simplelru instead of reinventing LRU
logic. This should make it easier to see whether it's correct.
* consensus/ethash: restore 'future item' logic in lru
* consensus/ethash: use mmap even in test mode
This makes it possible to shorten the time taken for TestCacheFileEvict.
* consensus/ethash: shuffle func calc*Size comments around
* consensus/ethash: ensure future cache/dataset is in the lru cache
* consensus/ethash: add issue link to the new test
* consensus/ethash: fix vet
* consensus/ethash: fix test
* consensus: tiny issue + nitpick fixes
---
consensus/ethash/algorithm.go | 6 +-
consensus/ethash/algorithm_go1.7.go | 4 +-
consensus/ethash/algorithm_go1.8.go | 34 +--
consensus/ethash/algorithm_go1.8_test.go | 23 +-
consensus/ethash/consensus.go | 10 +-
consensus/ethash/ethash.go | 288 ++++++++++-------------
consensus/ethash/ethash_test.go | 39 +++
consensus/ethash/sealer.go | 17 +-
8 files changed, 208 insertions(+), 213 deletions(-)
diff --git a/consensus/ethash/algorithm.go b/consensus/ethash/algorithm.go
index 76f19252f..10767bb31 100644
--- a/consensus/ethash/algorithm.go
+++ b/consensus/ethash/algorithm.go
@@ -355,9 +355,11 @@ func hashimotoFull(dataset []uint32, hash []byte, nonce uint64) ([]byte, []byte)
return hashimoto(hash, nonce, uint64(len(dataset))*4, lookup)
}
+const maxEpoch = 2048
+
// datasetSizes is a lookup table for the ethash dataset size for the first 2048
// epochs (i.e. 61440000 blocks).
-var datasetSizes = []uint64{
+var datasetSizes = [maxEpoch]uint64{
1073739904, 1082130304, 1090514816, 1098906752, 1107293056,
1115684224, 1124070016, 1132461952, 1140849536, 1149232768,
1157627776, 1166013824, 1174404736, 1182786944, 1191180416,
@@ -771,7 +773,7 @@ var datasetSizes = []uint64{
// cacheSizes is a lookup table for the ethash verification cache size for the
// first 2048 epochs (i.e. 61440000 blocks).
-var cacheSizes = []uint64{
+var cacheSizes = [maxEpoch]uint64{
16776896, 16907456, 17039296, 17170112, 17301056, 17432512, 17563072,
17693888, 17824192, 17955904, 18087488, 18218176, 18349504, 18481088,
18611392, 18742336, 18874304, 19004224, 19135936, 19267264, 19398208,
diff --git a/consensus/ethash/algorithm_go1.7.go b/consensus/ethash/algorithm_go1.7.go
index c34d041c3..c7f7f48e4 100644
--- a/consensus/ethash/algorithm_go1.7.go
+++ b/consensus/ethash/algorithm_go1.7.go
@@ -25,7 +25,7 @@ package ethash
func cacheSize(block uint64) uint64 {
// If we have a pre-generated value, use that
epoch := int(block / epochLength)
- if epoch < len(cacheSizes) {
+ if epoch < maxEpoch {
return cacheSizes[epoch]
}
// We don't have a way to verify primes fast before Go 1.8
@@ -39,7 +39,7 @@ func cacheSize(block uint64) uint64 {
func datasetSize(block uint64) uint64 {
// If we have a pre-generated value, use that
epoch := int(block / epochLength)
- if epoch < len(datasetSizes) {
+ if epoch < maxEpoch {
return datasetSizes[epoch]
}
// We don't have a way to verify primes fast before Go 1.8
diff --git a/consensus/ethash/algorithm_go1.8.go b/consensus/ethash/algorithm_go1.8.go
index d691b758f..975fdffe5 100644
--- a/consensus/ethash/algorithm_go1.8.go
+++ b/consensus/ethash/algorithm_go1.8.go
@@ -20,17 +20,20 @@ package ethash
import "math/big"
-// cacheSize calculates and returns the size of the ethash verification cache that
-// belongs to a certain block number. The cache size grows linearly, however, we
-// always take the highest prime below the linearly growing threshold in order to
-// reduce the risk of accidental regularities leading to cyclic behavior.
+// cacheSize returns the size of the ethash verification cache that belongs to a certain
+// block number.
func cacheSize(block uint64) uint64 {
- // If we have a pre-generated value, use that
epoch := int(block / epochLength)
- if epoch < len(cacheSizes) {
+ if epoch < maxEpoch {
return cacheSizes[epoch]
}
- // No known cache size, calculate manually (sanity branch only)
+ return calcCacheSize(epoch)
+}
+
+// calcCacheSize calculates the cache size for epoch. The cache size grows linearly,
+// however, we always take the highest prime below the linearly growing threshold in order
+// to reduce the risk of accidental regularities leading to cyclic behavior.
+func calcCacheSize(epoch int) uint64 {
size := cacheInitBytes + cacheGrowthBytes*uint64(epoch) - hashBytes
for !new(big.Int).SetUint64(size / hashBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
size -= 2 * hashBytes
@@ -38,17 +41,20 @@ func cacheSize(block uint64) uint64 {
return size
}
-// datasetSize calculates and returns the size of the ethash mining dataset that
-// belongs to a certain block number. The dataset size grows linearly, however, we
-// always take the highest prime below the linearly growing threshold in order to
-// reduce the risk of accidental regularities leading to cyclic behavior.
+// datasetSize returns the size of the ethash mining dataset that belongs to a certain
+// block number.
func datasetSize(block uint64) uint64 {
- // If we have a pre-generated value, use that
epoch := int(block / epochLength)
- if epoch < len(datasetSizes) {
+ if epoch < maxEpoch {
return datasetSizes[epoch]
}
- // No known dataset size, calculate manually (sanity branch only)
+ return calcDatasetSize(epoch)
+}
+
+// calcDatasetSize calculates the dataset size for epoch. The dataset size grows linearly,
+// however, we always take the highest prime below the linearly growing threshold in order
+// to reduce the risk of accidental regularities leading to cyclic behavior.
+func calcDatasetSize(epoch int) uint64 {
size := datasetInitBytes + datasetGrowthBytes*uint64(epoch) - mixBytes
for !new(big.Int).SetUint64(size / mixBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
size -= 2 * mixBytes
diff --git a/consensus/ethash/algorithm_go1.8_test.go b/consensus/ethash/algorithm_go1.8_test.go
index a822944a6..6648bd6a9 100644
--- a/consensus/ethash/algorithm_go1.8_test.go
+++ b/consensus/ethash/algorithm_go1.8_test.go
@@ -23,24 +23,15 @@ import "testing"
// Tests whether the dataset size calculator works correctly by cross checking the
// hard coded lookup table with the value generated by it.
func TestSizeCalculations(t *testing.T) {
- var tests []uint64
-
- // Verify all the cache sizes from the lookup table
- defer func(sizes []uint64) { cacheSizes = sizes }(cacheSizes)
- tests, cacheSizes = cacheSizes, []uint64{}
-
- for i, test := range tests {
- if size := cacheSize(uint64(i*epochLength) + 1); size != test {
- t.Errorf("cache %d: cache size mismatch: have %d, want %d", i, size, test)
+ // Verify all the cache and dataset sizes from the lookup table.
+ for epoch, want := range cacheSizes {
+ if size := calcCacheSize(epoch); size != want {
+ t.Errorf("cache %d: cache size mismatch: have %d, want %d", epoch, size, want)
}
}
- // Verify all the dataset sizes from the lookup table
- defer func(sizes []uint64) { datasetSizes = sizes }(datasetSizes)
- tests, datasetSizes = datasetSizes, []uint64{}
-
- for i, test := range tests {
- if size := datasetSize(uint64(i*epochLength) + 1); size != test {
- t.Errorf("dataset %d: dataset size mismatch: have %d, want %d", i, size, test)
+ for epoch, want := range datasetSizes {
+ if size := calcDatasetSize(epoch); size != want {
+ t.Errorf("dataset %d: dataset size mismatch: have %d, want %d", epoch, size, want)
}
}
}
diff --git a/consensus/ethash/consensus.go b/consensus/ethash/consensus.go
index 82d23c92b..92a23d4a4 100644
--- a/consensus/ethash/consensus.go
+++ b/consensus/ethash/consensus.go
@@ -476,7 +476,7 @@ func (ethash *Ethash) VerifySeal(chain consensus.ChainReader, header *types.Head
}
// Sanity check that the block number is below the lookup table size (60M blocks)
number := header.Number.Uint64()
- if number/epochLength >= uint64(len(cacheSizes)) {
+ if number/epochLength >= maxEpoch {
// Go < 1.7 cannot calculate new cache/dataset sizes (no fast prime check)
return errNonceOutOfRange
}
@@ -484,14 +484,18 @@ func (ethash *Ethash) VerifySeal(chain consensus.ChainReader, header *types.Head
if header.Difficulty.Sign() <= 0 {
return errInvalidDifficulty
}
+
// Recompute the digest and PoW value and verify against the header
cache := ethash.cache(number)
-
size := datasetSize(number)
if ethash.config.PowMode == ModeTest {
size = 32 * 1024
}
- digest, result := hashimotoLight(size, cache, header.HashNoNonce().Bytes(), header.Nonce.Uint64())
+ digest, result := hashimotoLight(size, cache.cache, header.HashNoNonce().Bytes(), header.Nonce.Uint64())
+ // Caches are unmapped in a finalizer. Ensure that the cache stays live
+ // until after the call to hashimotoLight so it's not unmapped while being used.
+ runtime.KeepAlive(cache)
+
if !bytes.Equal(header.MixDigest[:], digest) {
return errInvalidMixDigest
}
diff --git a/consensus/ethash/ethash.go b/consensus/ethash/ethash.go
index a78b3a895..91e20112a 100644
--- a/consensus/ethash/ethash.go
+++ b/consensus/ethash/ethash.go
@@ -26,6 +26,7 @@ import (
"os"
"path/filepath"
"reflect"
+ "runtime"
"strconv"
"sync"
"time"
@@ -35,6 +36,7 @@ import (
"github.com/ethereum/go-ethereum/consensus"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rpc"
+ "github.com/hashicorp/golang-lru/simplelru"
metrics "github.com/rcrowley/go-metrics"
)
@@ -142,32 +144,82 @@ func memoryMapAndGenerate(path string, size uint64, generator func(buffer []uint
return memoryMap(path)
}
+// lru tracks caches or datasets by their last use time, keeping at most N of them.
+type lru struct {
+ what string
+ new func(epoch uint64) interface{}
+ mu sync.Mutex
+ // Items are kept in a LRU cache, but there is a special case:
+ // We always keep an item for (highest seen epoch) + 1 as the 'future item'.
+ cache *simplelru.LRU
+ future uint64
+ futureItem interface{}
+}
+
+// newlru create a new least-recently-used cache for ither the verification caches
+// or the mining datasets.
+func newlru(what string, maxItems int, new func(epoch uint64) interface{}) *lru {
+ if maxItems <= 0 {
+ maxItems = 1
+ }
+ cache, _ := simplelru.NewLRU(maxItems, func(key, value interface{}) {
+ log.Trace("Evicted ethash "+what, "epoch", key)
+ })
+ return &lru{what: what, new: new, cache: cache}
+}
+
+// get retrieves or creates an item for the given epoch. The first return value is always
+// non-nil. The second return value is non-nil if lru thinks that an item will be useful in
+// the near future.
+func (lru *lru) get(epoch uint64) (item, future interface{}) {
+ lru.mu.Lock()
+ defer lru.mu.Unlock()
+
+ // Get or create the item for the requested epoch.
+ item, ok := lru.cache.Get(epoch)
+ if !ok {
+ if lru.future > 0 && lru.future == epoch {
+ item = lru.futureItem
+ } else {
+ log.Trace("Requiring new ethash "+lru.what, "epoch", epoch)
+ item = lru.new(epoch)
+ }
+ lru.cache.Add(epoch, item)
+ }
+ // Update the 'future item' if epoch is larger than previously seen.
+ if epoch < maxEpoch-1 && lru.future < epoch+1 {
+ log.Trace("Requiring new future ethash "+lru.what, "epoch", epoch+1)
+ future = lru.new(epoch + 1)
+ lru.future = epoch + 1
+ lru.futureItem = future
+ }
+ return item, future
+}
+
// cache wraps an ethash cache with some metadata to allow easier concurrent use.
type cache struct {
- epoch uint64 // Epoch for which this cache is relevant
-
- dump *os.File // File descriptor of the memory mapped cache
- mmap mmap.MMap // Memory map itself to unmap before releasing
+ epoch uint64 // Epoch for which this cache is relevant
+ dump *os.File // File descriptor of the memory mapped cache
+ mmap mmap.MMap // Memory map itself to unmap before releasing
+ cache []uint32 // The actual cache data content (may be memory mapped)
+ once sync.Once // Ensures the cache is generated only once
+}
- cache []uint32 // The actual cache data content (may be memory mapped)
- used time.Time // Timestamp of the last use for smarter eviction
- once sync.Once // Ensures the cache is generated only once
- lock sync.Mutex // Ensures thread safety for updating the usage time
+// newCache creates a new ethash verification cache and returns it as a plain Go
+// interface to be usable in an LRU cache.
+func newCache(epoch uint64) interface{} {
+ return &cache{epoch: epoch}
}
// generate ensures that the cache content is generated before use.
func (c *cache) generate(dir string, limit int, test bool) {
c.once.Do(func() {
- // If we have a testing cache, generate and return
- if test {
- c.cache = make([]uint32, 1024/4)
- generateCache(c.cache, c.epoch, seedHash(c.epoch*epochLength+1))
- return
- }
- // If we don't store anything on disk, generate and return
size := cacheSize(c.epoch*epochLength + 1)
seed := seedHash(c.epoch*epochLength + 1)
-
+ if test {
+ size = 1024
+ }
+ // If we don't store anything on disk, generate and return.
if dir == "" {
c.cache = make([]uint32, size/4)
generateCache(c.cache, c.epoch, seed)
@@ -181,6 +233,10 @@ func (c *cache) generate(dir string, limit int, test bool) {
path := filepath.Join(dir, fmt.Sprintf("cache-R%d-%x%s", algorithmRevision, seed[:8], endian))
logger := log.New("epoch", c.epoch)
+ // We're about to mmap the file, ensure that the mapping is cleaned up when the
+ // cache becomes unused.
+ runtime.SetFinalizer(c, (*cache).finalizer)
+
// Try to load the file from disk and memory map it
var err error
c.dump, c.mmap, c.cache, err = memoryMap(path)
@@ -207,49 +263,41 @@ func (c *cache) generate(dir string, limit int, test bool) {
})
}
-// release closes any file handlers and memory maps open.
-func (c *cache) release() {
+// finalizer unmaps the memory and closes the file.
+func (c *cache) finalizer() {
if c.mmap != nil {
c.mmap.Unmap()
- c.mmap = nil
- }
- if c.dump != nil {
c.dump.Close()
- c.dump = nil
+ c.mmap, c.dump = nil, nil
}
}
// dataset wraps an ethash dataset with some metadata to allow easier concurrent use.
type dataset struct {
- epoch uint64 // Epoch for which this cache is relevant
-
- dump *os.File // File descriptor of the memory mapped cache
- mmap mmap.MMap // Memory map itself to unmap before releasing
+ epoch uint64 // Epoch for which this cache is relevant
+ dump *os.File // File descriptor of the memory mapped cache
+ mmap mmap.MMap // Memory map itself to unmap before releasing
+ dataset []uint32 // The actual cache data content
+ once sync.Once // Ensures the cache is generated only once
+}
- dataset []uint32 // The actual cache data content
- used time.Time // Timestamp of the last use for smarter eviction
- once sync.Once // Ensures the cache is generated only once
- lock sync.Mutex // Ensures thread safety for updating the usage time
+// newDataset creates a new ethash mining dataset and returns it as a plain Go
+// interface to be usable in an LRU cache.
+func newDataset(epoch uint64) interface{} {
+ return &dataset{epoch: epoch}
}
// generate ensures that the dataset content is generated before use.
func (d *dataset) generate(dir string, limit int, test bool) {
d.once.Do(func() {
- // If we have a testing dataset, generate and return
- if test {
- cache := make([]uint32, 1024/4)
- generateCache(cache, d.epoch, seedHash(d.epoch*epochLength+1))
-
- d.dataset = make([]uint32, 32*1024/4)
- generateDataset(d.dataset, d.epoch, cache)
-
- return
- }
- // If we don't store anything on disk, generate and return
csize := cacheSize(d.epoch*epochLength + 1)
dsize := datasetSize(d.epoch*epochLength + 1)
seed := seedHash(d.epoch*epochLength + 1)
-
+ if test {
+ csize = 1024
+ dsize = 32 * 1024
+ }
+ // If we don't store anything on disk, generate and return
if dir == "" {
cache := make([]uint32, csize/4)
generateCache(cache, d.epoch, seed)
@@ -265,6 +313,10 @@ func (d *dataset) generate(dir string, limit int, test bool) {
path := filepath.Join(dir, fmt.Sprintf("full-R%d-%x%s", algorithmRevision, seed[:8], endian))
logger := log.New("epoch", d.epoch)
+ // We're about to mmap the file, ensure that the mapping is cleaned up when the
+ // cache becomes unused.
+ runtime.SetFinalizer(d, (*dataset).finalizer)
+
// Try to load the file from disk and memory map it
var err error
d.dump, d.mmap, d.dataset, err = memoryMap(path)
@@ -294,15 +346,12 @@ func (d *dataset) generate(dir string, limit int, test bool) {
})
}
-// release closes any file handlers and memory maps open.
-func (d *dataset) release() {
+// finalizer closes any file handlers and memory maps open.
+func (d *dataset) finalizer() {
if d.mmap != nil {
d.mmap.Unmap()
- d.mmap = nil
- }
- if d.dump != nil {
d.dump.Close()
- d.dump = nil
+ d.mmap, d.dump = nil, nil
}
}
@@ -310,14 +359,12 @@ func (d *dataset) release() {
func MakeCache(block uint64, dir string) {
c := cache{epoch: block / epochLength}
c.generate(dir, math.MaxInt32, false)
- c.release()
}
// MakeDataset generates a new ethash dataset and optionally stores it to disk.
func MakeDataset(block uint64, dir string) {
d := dataset{epoch: block / epochLength}
d.generate(dir, math.MaxInt32, false)
- d.release()
}
// Mode defines the type and amount of PoW verification an ethash engine makes.
@@ -347,10 +394,8 @@ type Config struct {
type Ethash struct {
config Config
- caches map[uint64]*cache // In memory caches to avoid regenerating too often
- fcache *cache // Pre-generated cache for the estimated future epoch
- datasets map[uint64]*dataset // In memory datasets to avoid regenerating too often
- fdataset *dataset // Pre-generated dataset for the estimated future epoch
+ caches *lru // In memory caches to avoid regenerating too often
+ datasets *lru // In memory datasets to avoid regenerating too often
// Mining related fields
rand *rand.Rand // Properly seeded random source for nonces
@@ -380,8 +425,8 @@ func New(config Config) *Ethash {
}
return &Ethash{
config: config,
- caches: make(map[uint64]*cache),
- datasets: make(map[uint64]*dataset),
+ caches: newlru("cache", config.CachesInMem, newCache),
+ datasets: newlru("dataset", config.DatasetsInMem, newDataset),
update: make(chan struct{}),
hashrate: metrics.NewMeter(),
}
@@ -390,16 +435,7 @@ func New(config Config) *Ethash {
// NewTester creates a small sized ethash PoW scheme useful only for testing
// purposes.
func NewTester() *Ethash {
- return &Ethash{
- config: Config{
- CachesInMem: 1,
- PowMode: ModeTest,
- },
- caches: make(map[uint64]*cache),
- datasets: make(map[uint64]*dataset),
- update: make(chan struct{}),
- hashrate: metrics.NewMeter(),
- }
+ return New(Config{CachesInMem: 1, PowMode: ModeTest})
}
// NewFaker creates a ethash consensus engine with a fake PoW scheme that accepts
@@ -456,126 +492,40 @@ func NewShared() *Ethash {
// cache tries to retrieve a verification cache for the specified block number
// by first checking against a list of in-memory caches, then against caches
// stored on disk, and finally generating one if none can be found.
-func (ethash *Ethash) cache(block uint64) []uint32 {
+func (ethash *Ethash) cache(block uint64) *cache {
epoch := block / epochLength
+ currentI, futureI := ethash.caches.get(epoch)
+ current := currentI.(*cache)
- // If we have a PoW for that epoch, use that
- ethash.lock.Lock()
-
- current, future := ethash.caches[epoch], (*cache)(nil)
- if current == nil {
- // No in-memory cache, evict the oldest if the cache limit was reached
- for len(ethash.caches) > 0 && len(ethash.caches) >= ethash.config.CachesInMem {
- var evict *cache
- for _, cache := range ethash.caches {
- if evict == nil || evict.used.After(cache.used) {
- evict = cache
- }
- }
- delete(ethash.caches, evict.epoch)
- evict.release()
-
- log.Trace("Evicted ethash cache", "epoch", evict.epoch, "used", evict.used)
- }
- // If we have the new cache pre-generated, use that, otherwise create a new one
- if ethash.fcache != nil && ethash.fcache.epoch == epoch {
- log.Trace("Using pre-generated cache", "epoch", epoch)
- current, ethash.fcache = ethash.fcache, nil
- } else {
- log.Trace("Requiring new ethash cache", "epoch", epoch)
- current = &cache{epoch: epoch}
- }
- ethash.caches[epoch] = current
-
- // If we just used up the future cache, or need a refresh, regenerate
- if ethash.fcache == nil || ethash.fcache.epoch <= epoch {
- if ethash.fcache != nil {
- ethash.fcache.release()
- }
- log.Trace("Requiring new future ethash cache", "epoch", epoch+1)
- future = &cache{epoch: epoch + 1}
- ethash.fcache = future
- }
- // New current cache, set its initial timestamp
- current.used = time.Now()
- }
- ethash.lock.Unlock()
-
- // Wait for generation finish, bump the timestamp and finalize the cache
+ // Wait for generation finish.
current.generate(ethash.config.CacheDir, ethash.config.CachesOnDisk, ethash.config.PowMode == ModeTest)
- current.lock.Lock()
- current.used = time.Now()
- current.lock.Unlock()
-
- // If we exhausted the future cache, now's a good time to regenerate it
- if future != nil {
+ // If we need a new future cache, now's a good time to regenerate it.
+ if futureI != nil {
+ future := futureI.(*cache)
go future.generate(ethash.config.CacheDir, ethash.config.CachesOnDisk, ethash.config.PowMode == ModeTest)
}
- return current.cache
+ return current
}
// dataset tries to retrieve a mining dataset for the specified block number
// by first checking against a list of in-memory datasets, then against DAGs
// stored on disk, and finally generating one if none can be found.
-func (ethash *Ethash) dataset(block uint64) []uint32 {
+func (ethash *Ethash) dataset(block uint64) *dataset {
epoch := block / epochLength
+ currentI, futureI := ethash.datasets.get(epoch)
+ current := currentI.(*dataset)
- // If we have a PoW for that epoch, use that
- ethash.lock.Lock()
-
- current, future := ethash.datasets[epoch], (*dataset)(nil)
- if current == nil {
- // No in-memory dataset, evict the oldest if the dataset limit was reached
- for len(ethash.datasets) > 0 && len(ethash.datasets) >= ethash.config.DatasetsInMem {
- var evict *dataset
- for _, dataset := range ethash.datasets {
- if evict == nil || evict.used.After(dataset.used) {
- evict = dataset
- }
- }
- delete(ethash.datasets, evict.epoch)
- evict.release()
-
- log.Trace("Evicted ethash dataset", "epoch", evict.epoch, "used", evict.used)
- }
- // If we have the new cache pre-generated, use that, otherwise create a new one
- if ethash.fdataset != nil && ethash.fdataset.epoch == epoch {
- log.Trace("Using pre-generated dataset", "epoch", epoch)
- current = &dataset{epoch: ethash.fdataset.epoch} // Reload from disk
- ethash.fdataset = nil
- } else {
- log.Trace("Requiring new ethash dataset", "epoch", epoch)
- current = &dataset{epoch: epoch}
- }
- ethash.datasets[epoch] = current
-
- // If we just used up the future dataset, or need a refresh, regenerate
- if ethash.fdataset == nil || ethash.fdataset.epoch <= epoch {
- if ethash.fdataset != nil {
- ethash.fdataset.release()
- }
- log.Trace("Requiring new future ethash dataset", "epoch", epoch+1)
- future = &dataset{epoch: epoch + 1}
- ethash.fdataset = future
- }
- // New current dataset, set its initial timestamp
- current.used = time.Now()
- }
- ethash.lock.Unlock()
-
- // Wait for generation finish, bump the timestamp and finalize the cache
+ // Wait for generation finish.
current.generate(ethash.config.DatasetDir, ethash.config.DatasetsOnDisk, ethash.config.PowMode == ModeTest)
- current.lock.Lock()
- current.used = time.Now()
- current.lock.Unlock()
-
- // If we exhausted the future dataset, now's a good time to regenerate it
- if future != nil {
+ // If we need a new future dataset, now's a good time to regenerate it.
+ if futureI != nil {
+ future := futureI.(*dataset)
go future.generate(ethash.config.DatasetDir, ethash.config.DatasetsOnDisk, ethash.config.PowMode == ModeTest)
}
- return current.dataset
+
+ return current
}
// Threads returns the number of mining threads currently enabled. This doesn't
diff --git a/consensus/ethash/ethash_test.go b/consensus/ethash/ethash_test.go
index b3a2f32f7..31116da43 100644
--- a/consensus/ethash/ethash_test.go
+++ b/consensus/ethash/ethash_test.go
@@ -17,7 +17,11 @@
package ethash
import (
+ "io/ioutil"
"math/big"
+ "math/rand"
+ "os"
+ "sync"
"testing"
"github.com/ethereum/go-ethereum/core/types"
@@ -38,3 +42,38 @@ func TestTestMode(t *testing.T) {
t.Fatalf("unexpected verification error: %v", err)
}
}
+
+// This test checks that cache lru logic doesn't crash under load.
+// It reproduces https://github.com/ethereum/go-ethereum/issues/14943
+func TestCacheFileEvict(t *testing.T) {
+ tmpdir, err := ioutil.TempDir("", "ethash-test")
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer os.RemoveAll(tmpdir)
+ e := New(Config{CachesInMem: 3, CachesOnDisk: 10, CacheDir: tmpdir, PowMode: ModeTest})
+
+ workers := 8
+ epochs := 100
+ var wg sync.WaitGroup
+ wg.Add(workers)
+ for i := 0; i < workers; i++ {
+ go verifyTest(&wg, e, i, epochs)
+ }
+ wg.Wait()
+}
+
+func verifyTest(wg *sync.WaitGroup, e *Ethash, workerIndex, epochs int) {
+ defer wg.Done()
+
+ const wiggle = 4 * epochLength
+ r := rand.New(rand.NewSource(int64(workerIndex)))
+ for epoch := 0; epoch < epochs; epoch++ {
+ block := int64(epoch)*epochLength - wiggle/2 + r.Int63n(wiggle)
+ if block < 0 {
+ block = 0
+ }
+ head := &types.Header{Number: big.NewInt(block), Difficulty: big.NewInt(100)}
+ e.VerifySeal(nil, head)
+ }
+}
diff --git a/consensus/ethash/sealer.go b/consensus/ethash/sealer.go
index c2447e473..b5e742d8b 100644
--- a/consensus/ethash/sealer.go
+++ b/consensus/ethash/sealer.go
@@ -97,10 +97,9 @@ func (ethash *Ethash) Seal(chain consensus.ChainReader, block *types.Block, stop
func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan struct{}, found chan *types.Block) {
// Extract some data from the header
var (
- header = block.Header()
- hash = header.HashNoNonce().Bytes()
- target = new(big.Int).Div(maxUint256, header.Difficulty)
-
+ header = block.Header()
+ hash = header.HashNoNonce().Bytes()
+ target = new(big.Int).Div(maxUint256, header.Difficulty)
number = header.Number.Uint64()
dataset = ethash.dataset(number)
)
@@ -111,13 +110,14 @@ func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan s
)
logger := log.New("miner", id)
logger.Trace("Started ethash search for new nonces", "seed", seed)
+search:
for {
select {
case <-abort:
// Mining terminated, update stats and abort
logger.Trace("Ethash nonce search aborted", "attempts", nonce-seed)
ethash.hashrate.Mark(attempts)
- return
+ break search
default:
// We don't have to update hash rate on every nonce, so update after after 2^X nonces
@@ -127,7 +127,7 @@ func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan s
attempts = 0
}
// Compute the PoW value of this nonce
- digest, result := hashimotoFull(dataset, hash, nonce)
+ digest, result := hashimotoFull(dataset.dataset, hash, nonce)
if new(big.Int).SetBytes(result).Cmp(target) <= 0 {
// Correct nonce found, create a new header with it
header = types.CopyHeader(header)
@@ -141,9 +141,12 @@ func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan s
case <-abort:
logger.Trace("Ethash nonce found but discarded", "attempts", nonce-seed, "nonce", nonce)
}
- return
+ break search
}
nonce++
}
}
+ // Datasets are unmapped in a finalizer. Ensure that the dataset stays live
+ // during sealing so it's not unmapped while being read.
+ runtime.KeepAlive(dataset)
}
--
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