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sortless compaction

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This commit is contained in:
vyzo 2022-01-30 15:33:15 +02:00
parent a4f720d866
commit dbc8903bac
2 changed files with 347 additions and 279 deletions
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79
blockstore/splitstore/splitstore.go
View File

@ -129,8 +129,6 @@ type SplitStore struct {
headChangeMx sync.Mutex
coldPurgeSize int
chain ChainAccessor
ds dstore.Datastore
cold bstore.Blockstore
@ -158,6 +156,7 @@ type SplitStore struct {
txnRefsMx sync.Mutex
txnRefs map[cid.Cid]struct{}
txnMissing map[cid.Cid]struct{}
txnMarkSet MarkSet
// registered protectors
protectors []func(func(cid.Cid) error) error
@ -194,8 +193,6 @@ func Open(path string, ds dstore.Datastore, hot, cold bstore.Blockstore, cfg *Co
cold: cold,
hot: hots,
markSetEnv: markSetEnv,
coldPurgeSize: defaultColdPurgeSize,
}
ss.txnViewsCond.L = &ss.txnViewsMx
@ -208,6 +205,14 @@ func Open(path string, ds dstore.Datastore, hot, cold bstore.Blockstore, cfg *Co
}
}
if ss.checkpointExists() {
log.Info("found compaction checkpoint; resuming compaction")
if err := ss.completeCompaction(); err != nil {
markSetEnv.Close()
return nil, xerrors.Errorf("error resuming compaction: %w", err)
}
}
return ss, nil
}
@ -230,6 +235,16 @@ func (s *SplitStore) Has(ctx context.Context, cid cid.Cid) (bool, error) {
s.txnLk.RLock()
defer s.txnLk.RUnlock()
// critical section
if s.txnMarkSet != nil {
has, err := s.txnMarkSet.Has(cid)
if has || err != nil {
return has, err
}
return s.cold.Has(ctx, cid)
}
has, err := s.hot.Has(ctx, cid)
if err != nil {
@ -257,6 +272,20 @@ func (s *SplitStore) Get(ctx context.Context, cid cid.Cid) (blocks.Block, error)
s.txnLk.RLock()
defer s.txnLk.RUnlock()
// critical section
if s.txnMarkSet != nil {
has, err := s.txnMarkSet.Has(cid)
if err != nil {
return nil, err
}
if has {
return s.hot.Get(ctx, cid)
}
return s.cold.Get(ctx, cid)
}
blk, err := s.hot.Get(ctx, cid)
switch err {
@ -294,6 +323,20 @@ func (s *SplitStore) GetSize(ctx context.Context, cid cid.Cid) (int, error) {
s.txnLk.RLock()
defer s.txnLk.RUnlock()
// critical section
if s.txnMarkSet != nil {
has, err := s.txnMarkSet.Has(cid)
if err != nil {
return 0, err
}
if has {
return s.hot.GetSize(ctx, cid)
}
return s.cold.GetSize(ctx, cid)
}
size, err := s.hot.GetSize(ctx, cid)
switch err {
@ -332,6 +375,11 @@ func (s *SplitStore) Put(ctx context.Context, blk blocks.Block) error {
s.debug.LogWrite(blk)
// critical section
if s.txnMarkSet != nil {
return s.txnMarkSet.Mark(blk.Cid())
}
s.trackTxnRef(blk.Cid())
return nil
}
@ -377,6 +425,11 @@ func (s *SplitStore) PutMany(ctx context.Context, blks []blocks.Block) error {
s.debug.LogWriteMany(blks)
// critical section
if s.txnMarkSet != nil {
return s.txnMarkSet.MarkMany(batch)
}
s.trackTxnRefMany(batch)
return nil
}
@ -436,6 +489,24 @@ func (s *SplitStore) View(ctx context.Context, cid cid.Cid, cb func([]byte) erro
return cb(data)
}
// critical section
s.txnLk.RLock()
if s.txnMarkSet != nil {
has, err := s.txnMarkSet.Has(cid)
s.txnLk.RUnlock()
if err != nil {
return err
}
if has {
return s.hot.View(ctx, cid, cb)
}
return s.cold.View(ctx, cid, cb)
}
s.txnLk.RUnlock()
// views are (optimistically) protected two-fold:
// - if there is an active transaction, then the reference is protected.
// - if there is no active transaction, active views are tracked in a

487
blockstore/splitstore/splitstore_compact.go
View File

@ -3,8 +3,9 @@ package splitstore
import (
"bytes"
"errors"
"os"
"path/filepath"
"runtime"
"sort"
"sync"
"sync/atomic"
"time"
@ -387,6 +388,12 @@ func (s *SplitStore) compact(curTs *types.TipSet) {
}
func (s *SplitStore) doCompact(curTs *types.TipSet) error {
if s.checkpointExists() {
// this really shouldn't happen, but if it somehow does, it means that the hotstore
// might be potentially inconsistent; abort compaction and notify the user to intervene.
return xerrors.Errorf("checkpoint exists; aborting compaction")
}
currentEpoch := curTs.Height()
boundaryEpoch := currentEpoch - CompactionBoundary
@ -409,9 +416,6 @@ func (s *SplitStore) doCompact(curTs *types.TipSet) error {
return err
}
// we are ready for concurrent marking
s.beginTxnMarking(markSet)
// 0. track all protected references at beginning of compaction; anything added later should
// be transactionally protected by the write
log.Info("protecting references with registered protectors")
@ -425,7 +429,7 @@ func (s *SplitStore) doCompact(curTs *types.TipSet) error {
log.Info("marking reachable objects")
startMark := time.Now()
var count int64
count := new(int64)
err = s.walkChain(curTs, boundaryEpoch, inclMsgsEpoch, &noopVisitor{},
func(c cid.Cid) error {
if isUnitaryObject(c) {
@ -441,7 +445,7 @@ func (s *SplitStore) doCompact(curTs *types.TipSet) error {
return errStopWalk
}
count++
atomic.AddInt64(count, 1)
return nil
})
@ -449,9 +453,9 @@ func (s *SplitStore) doCompact(curTs *types.TipSet) error {
return xerrors.Errorf("error marking: %w", err)
}
s.markSetSize = count + count>>2 // overestimate a bit
s.markSetSize = *count + *count>>2 // overestimate a bit
log.Infow("marking done", "took", time.Since(startMark), "marked", count)
log.Infow("marking done", "took", time.Since(startMark), "marked", *count)
if err := s.checkClosing(); err != nil {
return err
@ -471,10 +475,15 @@ func (s *SplitStore) doCompact(curTs *types.TipSet) error {
log.Info("collecting cold objects")
startCollect := time.Now()
coldw, err := NewColdSetWriter(s.coldSetPath())
if err != nil {
return xerrors.Errorf("error creating coldset: %w", err)
}
defer coldw.Close() //nolint:errcheck
// some stats for logging
var hotCnt, coldCnt int
cold := make([]cid.Cid, 0, s.coldPurgeSize)
err = s.hot.ForEachKey(func(c cid.Cid) error {
// was it marked?
mark, err := markSet.Has(c)
@ -488,7 +497,7 @@ func (s *SplitStore) doCompact(curTs *types.TipSet) error {
}
// it's cold, mark it as candidate for move
cold = append(cold, c)
coldw.Write(c)
coldCnt++
return nil
@ -498,12 +507,12 @@ func (s *SplitStore) doCompact(curTs *types.TipSet) error {
return xerrors.Errorf("error collecting cold objects: %w", err)
}
log.Infow("cold collection done", "took", time.Since(startCollect))
if coldCnt > 0 {
s.coldPurgeSize = coldCnt + coldCnt>>2 // overestimate a bit
if err := coldw.Close(); err != nil {
return xerrors.Errorf("error closing coldset: %w", err)
}
log.Infow("cold collection done", "took", time.Since(startCollect))
log.Infow("compaction stats", "hot", hotCnt, "cold", coldCnt)
stats.Record(s.ctx, metrics.SplitstoreCompactionHot.M(int64(hotCnt)))
stats.Record(s.ctx, metrics.SplitstoreCompactionCold.M(int64(coldCnt)))
@ -512,20 +521,17 @@ func (s *SplitStore) doCompact(curTs *types.TipSet) error {
return err
}
// now that we have collected cold objects, check for missing references from transactional i/o
// and disable further collection of such references (they will not be acted upon as we can't
// possibly delete objects we didn't have when we were collecting cold objects)
s.waitForMissingRefs(markSet)
if err := s.checkClosing(); err != nil {
return err
coldr, err := NewColdSetReader(s.coldSetPath())
if err != nil {
return xerrors.Errorf("error opening coldset: %w", err)
}
defer coldr.Close() //nolint:errcheck
// 3. copy the cold objects to the coldstore -- if we have one
if !s.cfg.DiscardColdBlocks {
log.Info("moving cold objects to the coldstore")
startMove := time.Now()
err = s.moveColdBlocks(cold)
err = s.moveColdBlocks(coldr)
if err != nil {
return xerrors.Errorf("error moving cold objects: %w", err)
}
@ -534,41 +540,57 @@ func (s *SplitStore) doCompact(curTs *types.TipSet) error {
if err := s.checkClosing(); err != nil {
return err
}
if err := coldr.Reset(); err != nil {
return xerrors.Errorf("error resetting coldset: %w", err)
}
}
// 4. sort cold objects so that the dags with most references are deleted first
// this ensures that we can't refer to a dag with its consituents already deleted, ie
// we lave no dangling references.
log.Info("sorting cold objects")
startSort := time.Now()
err = s.sortObjects(cold)
if err != nil {
return xerrors.Errorf("error sorting objects: %w", err)
}
log.Infow("sorting done", "took", time.Since(startSort))
// 4.1 protect transactional refs once more
// strictly speaking, this is not necessary as purge will do it before deleting each
// batch. however, there is likely a largish number of references accumulated during
// ths sort and this protects before entering pruge context.
err = s.protectTxnRefs(markSet)
if err != nil {
return xerrors.Errorf("error protecting transactional refs: %w", err)
// 4. Purge cold objects with checkpointing for recovery.
// This is the critical section of compaction, whereby any cold object not in the markSet is
// considered already deleted.
// We delete cold objects in batches, holding the transaction lock, where we check the markSet
// again for new references created by the VM.
// After each batch, we write a checkpoint to disk; if the process is interrupted before completion,
// the process will continue from the checkpoint in the next recovery.
if err := s.beginCriticalSection(markSet); err != nil {
return xerrors.Errorf("error beginning critical section: %w", err)
}
if err := s.checkClosing(); err != nil {
return err
}
checkpoint, err := NewCheckpoint(s.checkpointPath())
if err != nil {
return xerrors.Errorf("error creating checkpoint: %w", err)
}
defer checkpoint.Close() //nolint:errcheck
// 5. purge cold objects from the hotstore, taking protected references into account
log.Info("purging cold objects from the hotstore")
startPurge := time.Now()
err = s.purge(cold, markSet)
err = s.purge(coldr, checkpoint, markSet)
if err != nil {
return xerrors.Errorf("error purging cold blocks: %w", err)
return xerrors.Errorf("error purging cold objects: %w", err)
}
log.Infow("purging cold objects from hotstore done", "took", time.Since(startPurge))
s.endCriticalSection()
if err := checkpoint.Close(); err != nil {
log.Warnf("error closing checkpoint: %s", err)
}
if err := os.Remove(s.checkpointPath()); err != nil {
log.Warnf("error removing checkpoint: %s", err)
}
if err := coldr.Close(); err != nil {
log.Warnf("error closing coldset: %s", err)
}
if err := os.Remove(s.coldSetPath()); err != nil {
log.Warnf("error removing coldset: %s", err)
}
// we are done; do some housekeeping
s.endTxnProtect()
s.gcHotstore()
@ -603,8 +625,22 @@ func (s *SplitStore) beginTxnProtect() {
s.txnMissing = make(map[cid.Cid]struct{})
}
func (s *SplitStore) beginTxnMarking(markSet MarkSet) {
log.Info("beginning transactional marking")
func (s *SplitStore) beginCriticalSection(markSet MarkSet) error {
log.Info("beginning critical section")
if err := markSet.BeginCriticalSection(); err != nil {
return xerrors.Errorf("error beginning critical section for markset: %w", err)
}
s.txnLk.Lock()
s.txnMarkSet = markSet
s.txnLk.Unlock()
if err := s.protectTxnRefs(markSet); err != nil {
return xerrors.Errorf("error protecting transactional references: %w", err)
}
return nil
}
func (s *SplitStore) endTxnProtect() {
@ -618,6 +654,17 @@ func (s *SplitStore) endTxnProtect() {
s.txnActive = false
s.txnRefs = nil
s.txnMissing = nil
s.txnMarkSet = nil
}
func (s *SplitStore) endCriticalSection() {
log.Info("ending critical section")
s.txnLk.Lock()
defer s.txnLk.Unlock()
s.txnMarkSet.EndCriticalSection()
s.txnMarkSet = nil
}
func (s *SplitStore) walkChain(ts *types.TipSet, inclState, inclMsgs abi.ChainEpoch,
@ -892,10 +939,10 @@ func (s *SplitStore) has(c cid.Cid) (bool, error) {
return s.cold.Has(s.ctx, c)
}
func (s *SplitStore) moveColdBlocks(cold []cid.Cid) error {
func (s *SplitStore) moveColdBlocks(coldr *ColdSetReader) error {
batch := make([]blocks.Block, 0, batchSize)
for _, c := range cold {
coldr.ForEach(func(c cid.Cid) error {
if err := s.checkClosing(); err != nil {
return err
}
@ -904,7 +951,7 @@ func (s *SplitStore) moveColdBlocks(cold []cid.Cid) error {
if err != nil {
if err == bstore.ErrNotFound {
log.Warnf("hotstore missing block %s", c)
continue
return nil
}
return xerrors.Errorf("error retrieving block %s from hotstore: %w", c, err)
@ -918,7 +965,9 @@ func (s *SplitStore) moveColdBlocks(cold []cid.Cid) error {
}
batch = batch[:0]
}
}
return nil
})
if len(batch) > 0 {
err := s.cold.PutMany(s.ctx, batch)
@ -930,160 +979,60 @@ func (s *SplitStore) moveColdBlocks(cold []cid.Cid) error {
return nil
}
// sorts a slice of objects heaviest first -- it's a little expensive but worth the
// guarantee that we don't leave dangling references behind, e.g. if we die in the middle
// of a purge.
func (s *SplitStore) sortObjects(cids []cid.Cid) error {
// we cache the keys to avoid making a gazillion of strings
keys := make(map[cid.Cid]string)
key := func(c cid.Cid) string {
s, ok := keys[c]
if !ok {
s = string(c.Hash())
keys[c] = s
}
return s
}
// compute sorting weights as the cumulative number of DAG links
weights := make(map[string]int)
for _, c := range cids {
// this can take quite a while, so check for shutdown with every opportunity
if err := s.checkClosing(); err != nil {
return err
}
w := s.getObjectWeight(c, weights, key)
weights[key(c)] = w
}
// sort!
sort.Slice(cids, func(i, j int) bool {
wi := weights[key(cids[i])]
wj := weights[key(cids[j])]
if wi == wj {
return bytes.Compare(cids[i].Hash(), cids[j].Hash()) > 0
}
return wi > wj
})
return nil
}
func (s *SplitStore) getObjectWeight(c cid.Cid, weights map[string]int, key func(cid.Cid) string) int {
w, ok := weights[key(c)]
if ok {
return w
}
// we treat block headers specially to avoid walking the entire chain
var hdr types.BlockHeader
err := s.view(c, func(data []byte) error {
return hdr.UnmarshalCBOR(bytes.NewBuffer(data))
})
if err == nil {
w1 := s.getObjectWeight(hdr.ParentStateRoot, weights, key)
weights[key(hdr.ParentStateRoot)] = w1
w2 := s.getObjectWeight(hdr.Messages, weights, key)
weights[key(hdr.Messages)] = w2
return 1 + w1 + w2
}
var links []cid.Cid
err = s.view(c, func(data []byte) error {
return cbg.ScanForLinks(bytes.NewReader(data), func(c cid.Cid) {
links = append(links, c)
})
})
if err != nil {
return 1
}
w = 1
for _, c := range links {
// these are internal refs, so dags will be dags
if c.Prefix().Codec != cid.DagCBOR {
w++
continue
}
wc := s.getObjectWeight(c, weights, key)
weights[key(c)] = wc
w += wc
}
return w
}
func (s *SplitStore) purgeBatch(cids []cid.Cid, deleteBatch func([]cid.Cid) error) error {
if len(cids) == 0 {
return nil
}
// we don't delete one giant batch of millions of objects, but rather do smaller batches
// so that we don't stop the world for an extended period of time
done := false
for i := 0; !done; i++ {
start := i * batchSize
end := start + batchSize
if end >= len(cids) {
end = len(cids)
done = true
}
err := deleteBatch(cids[start:end])
if err != nil {
return xerrors.Errorf("error deleting batch: %w", err)
}
}
return nil
}
func (s *SplitStore) purge(cids []cid.Cid, markSet MarkSet) error {
func (s *SplitStore) purge(coldr *ColdSetReader, checkpoint *Checkpoint, markSet MarkSet) error {
batch := make([]cid.Cid, 0, batchSize)
deadCids := make([]cid.Cid, 0, batchSize)
var purgeCnt, liveCnt int
defer func() {
log.Infow("purged cold objects", "purged", purgeCnt, "live", liveCnt)
}()
return s.purgeBatch(cids,
func(cids []cid.Cid) error {
deadCids := deadCids[:0]
deleteBatch := func() error {
pc, lc, err := s.purgeBatch(batch, deadCids, checkpoint, markSet)
purgeCnt += pc
liveCnt += lc
batch = batch[:0]
for {
if err := s.checkClosing(); err != nil {
return err
}
s.txnLk.Lock()
if len(s.txnRefs) == 0 {
// keep the lock!
break
err := coldr.ForEach(func(c cid.Cid) error {
batch = append(batch, c)
if len(batch) == batchSize {
return deleteBatch()
}
// unlock and protect
s.txnLk.Unlock()
return nil
})
err := s.protectTxnRefs(markSet)
if err != nil {
return xerrors.Errorf("error protecting transactional refs: %w", err)
}
return err
}
if len(batch) > 0 {
return deleteBatch()
}
return nil
}
func (s *SplitStore) purgeBatch(batch, deadCids []cid.Cid, checkpoint *Checkpoint, markSet MarkSet) (purgeCnt int, liveCnt int, err error) {
if err := s.checkClosing(); err != nil {
return 0, 0, err
}
s.txnLk.Lock()
defer s.txnLk.Unlock()
for _, c := range cids {
live, err := markSet.Has(c)
for _, c := range batch {
has, err := markSet.Has(c)
if err != nil {
return xerrors.Errorf("error checking for liveness: %w", err)
return 0, 0, xerrors.Errorf("error checking markset for liveness: %w", err)
}
if live {
if has {
liveCnt++
continue
}
@ -1091,91 +1040,139 @@ func (s *SplitStore) purge(cids []cid.Cid, markSet MarkSet) error {
deadCids = append(deadCids, c)
}
err := s.hot.DeleteMany(s.ctx, deadCids)
if err != nil {
return xerrors.Errorf("error purging cold objects: %w", err)
if len(deadCids) == 0 {
if err := checkpoint.Set(batch[len(batch)-1]); err != nil {
return 0, 0, xerrors.Errorf("error setting checkpoint: %w", err)
}
return 0, liveCnt, nil
}
if err := s.hot.DeleteMany(s.ctx, deadCids); err != nil {
return 0, liveCnt, xerrors.Errorf("error purging cold objects: %w", err)
}
s.debug.LogDelete(deadCids)
purgeCnt = len(deadCids)
purgeCnt += len(deadCids)
if err := checkpoint.Set(batch[len(batch)-1]); err != nil {
return purgeCnt, liveCnt, xerrors.Errorf("error setting checkpoint: %w", err)
}
return purgeCnt, liveCnt, nil
}
func (s *SplitStore) coldSetPath() string {
return filepath.Join(s.path, "coldset")
}
func (s *SplitStore) checkpointPath() string {
return filepath.Join(s.path, "checkpoint")
}
func (s *SplitStore) checkpointExists() bool {
_, err := os.Stat(s.checkpointPath())
return err == nil
}
func (s *SplitStore) completeCompaction() error {
checkpoint, last, err := OpenCheckpoint(s.checkpointPath())
if err != nil {
return xerrors.Errorf("error opening checkpoint: %w", err)
}
defer checkpoint.Close() //nolint:errcheck
coldr, err := NewColdSetReader(s.coldSetPath())
if err != nil {
return xerrors.Errorf("error opening coldset: %w", err)
}
defer coldr.Close() //nolint:errcheck
markSet, err := s.markSetEnv.Recover("live")
if err != nil {
return xerrors.Errorf("error recovering markset: %w", err)
}
defer markSet.Close() //nolint:errcheck
// PURGE
log.Info("purging cold objects from the hotstore")
startPurge := time.Now()
err = s.completePurge(coldr, checkpoint, last, markSet)
if err != nil {
return xerrors.Errorf("error purging cold objects: %w", err)
}
log.Infow("purging cold objects from hotstore done", "took", time.Since(startPurge))
markSet.EndCriticalSection()
if err := checkpoint.Close(); err != nil {
log.Warnf("error closing checkpoint: %s", err)
}
if err := os.Remove(s.checkpointPath()); err != nil {
log.Warnf("error removing checkpoint: %s", err)
}
if err := coldr.Close(); err != nil {
log.Warnf("error closing coldset: %s", err)
}
if err := os.Remove(s.coldSetPath()); err != nil {
log.Warnf("error removing coldset: %s", err)
}
// Note: at this point we can start the splitstore; a compaction should run on
// the first head change, which will trigger gc on the hotstore.
// We don't mind the second (back-to-back) compaction as the head will
// have advanced during marking and coldset accumulation.
return nil
})
}
// I really don't like having this code, but we seem to have some occasional DAG references with
// missing constituents. During testing in mainnet *some* of these references *sometimes* appeared
// after a little bit.
// We need to figure out where they are coming from and eliminate that vector, but until then we
// have this gem[TM].
// My best guess is that they are parent message receipts or yet to be computed state roots; magik
// thinks the cause may be block validation.
func (s *SplitStore) waitForMissingRefs(markSet MarkSet) {
s.txnLk.Lock()
missing := s.txnMissing
s.txnMissing = nil
s.txnLk.Unlock()
if len(missing) == 0 {
return
func (s *SplitStore) completePurge(coldr *ColdSetReader, checkpoint *Checkpoint, start cid.Cid, markSet MarkSet) error {
if !start.Defined() {
return s.purge(coldr, checkpoint, markSet)
}
log.Info("waiting for missing references")
start := time.Now()
count := 0
seeking := true
batch := make([]cid.Cid, 0, batchSize)
deadCids := make([]cid.Cid, 0, batchSize)
var purgeCnt, liveCnt int
defer func() {
log.Infow("waiting for missing references done", "took", time.Since(start), "marked", count)
log.Infow("purged cold objects", "purged", purgeCnt, "live", liveCnt)
}()
for i := 0; i < 3 && len(missing) > 0; i++ {
if err := s.checkClosing(); err != nil {
return
deleteBatch := func() error {
pc, lc, err := s.purgeBatch(batch, deadCids, checkpoint, markSet)
purgeCnt += pc
liveCnt += lc
batch = batch[:0]
return err
}
wait := time.Duration(i) * time.Minute
log.Infof("retrying for %d missing references in %s (attempt: %d)", len(missing), wait, i+1)
if wait > 0 {
time.Sleep(wait)
err := coldr.ForEach(func(c cid.Cid) error {
if seeking {
if start.Equals(c) {
seeking = false
}
return nil
}
batch = append(batch, c)
if len(batch) == batchSize {
return deleteBatch()
}
towalk := missing
visitor := newTmpVisitor()
missing = make(map[cid.Cid]struct{})
for c := range towalk {
err := s.walkObjectIncomplete(c, visitor,
func(c cid.Cid) error {
if isUnitaryObject(c) {
return errStopWalk
}
visit, err := markSet.Visit(c)
if err != nil {
return xerrors.Errorf("error visiting object: %w", err)
}
if !visit {
return errStopWalk
}
count++
return nil
},
func(c cid.Cid) error {
missing[c] = struct{}{}
return errStopWalk
})
if err != nil {
log.Warnf("error marking: %s", err)
}
}
return err
}
if len(missing) > 0 {
log.Warnf("still missing %d references", len(missing))
for c := range missing {
log.Warnf("unresolved missing reference: %s", c)
}
if len(batch) > 0 {
return deleteBatch()
}
return nil
}