diff options
author | Felix Lange <fjl@users.noreply.github.com> | 2018-01-23 18:05:30 +0800 |
---|---|---|
committer | Péter Szilágyi <peterke@gmail.com> | 2018-01-23 18:05:30 +0800 |
commit | 924065e19d08cc7e6af0b3a5b5b1ef3785b79bd4 (patch) | |
tree | 9aefabb6b4c375971570555486ce5b172660661d /consensus | |
parent | 5d4267911a7791bfa60f275a97347372fbf0ce99 (diff) | |
download | go-tangerine-924065e19d08cc7e6af0b3a5b5b1ef3785b79bd4.tar.gz go-tangerine-924065e19d08cc7e6af0b3a5b5b1ef3785b79bd4.tar.zst go-tangerine-924065e19d08cc7e6af0b3a5b5b1ef3785b79bd4.zip |
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
Diffstat (limited to 'consensus')
-rw-r--r-- | consensus/ethash/algorithm.go | 6 | ||||
-rw-r--r-- | consensus/ethash/algorithm_go1.7.go | 4 | ||||
-rw-r--r-- | consensus/ethash/algorithm_go1.8.go | 34 | ||||
-rw-r--r-- | consensus/ethash/algorithm_go1.8_test.go | 23 | ||||
-rw-r--r-- | consensus/ethash/consensus.go | 10 | ||||
-rw-r--r-- | consensus/ethash/ethash.go | 288 | ||||
-rw-r--r-- | consensus/ethash/ethash_test.go | 39 | ||||
-rw-r--r-- | 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) } |