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Merge pull request #354 from prometheus/cleandelete

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Add resilience to crashes during deletion
pull/5805/head
Fabian Reinartz 7 years ago committed by GitHub
parent 0b200798fe 087c4c6d3a
commit 16727277e4
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 98 additions and 110 deletions
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16
block.go
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@ -164,6 +164,13 @@ type BlockStats struct {
NumTombstones uint64 `json:"numTombstones,omitempty"`
}
// BlockDesc describes a block by ULID and time range.
type BlockDesc struct {
ULID ulid.ULID `json:"ulid"`
MinTime int64 `json:"minTime"`
MaxTime int64 `json:"maxTime"`
}
// BlockMetaCompaction holds information about compactions a block went through.
type BlockMetaCompaction struct {
// Maximum number of compaction cycles any source block has
@ -171,6 +178,9 @@ type BlockMetaCompaction struct {
Level int `json:"level"`
// ULIDs of all source head blocks that went into the block.
Sources []ulid.ULID `json:"sources,omitempty"`
// Short descriptions of the direct blocks that were used to create
// this block.
Parents []BlockDesc `json:"parents,omitempty"`
Failed bool `json:"failed,omitempty"`
}
@ -475,19 +485,17 @@ func (pb *Block) CleanTombstones(dest string, c Compactor) (*ulid.ULID, error) {
pb.tombstones.Iter(func(id uint64, ivs Intervals) error {
numStones += len(ivs)
return nil
})
if numStones == 0 {
return nil, nil
}
uid, err := c.Write(dest, pb, pb.meta.MinTime, pb.meta.MaxTime)
meta := pb.Meta()
uid, err := c.Write(dest, pb, pb.meta.MinTime, pb.meta.MaxTime, &meta)
if err != nil {
return nil, err
}
return &uid, nil
}

15
compact.go
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@ -55,7 +55,7 @@ type Compactor interface {
Plan(dir string) ([]string, error)
// Write persists a Block into a directory.
Write(dest string, b BlockReader, mint, maxt int64) (ulid.ULID, error)
Write(dest string, b BlockReader, mint, maxt int64, parent *BlockMeta) (ulid.ULID, error)
// Compact runs compaction against the provided directories. Must
// only be called concurrently with results of Plan().
@ -297,6 +297,11 @@ func compactBlockMetas(uid ulid.ULID, blocks ...*BlockMeta) *BlockMeta {
for _, s := range b.Compaction.Sources {
sources[s] = struct{}{}
}
res.Compaction.Parents = append(res.Compaction.Parents, BlockDesc{
ULID: b.ULID,
MinTime: b.MinTime,
MaxTime: b.MaxTime,
})
}
res.Compaction.Level++
@ -367,7 +372,7 @@ func (c *LeveledCompactor) Compact(dest string, dirs ...string) (uid ulid.ULID,
return uid, merr
}
func (c *LeveledCompactor) Write(dest string, b BlockReader, mint, maxt int64) (ulid.ULID, error) {
func (c *LeveledCompactor) Write(dest string, b BlockReader, mint, maxt int64, parent *BlockMeta) (ulid.ULID, error) {
entropy := rand.New(rand.NewSource(time.Now().UnixNano()))
uid := ulid.MustNew(ulid.Now(), entropy)
@ -379,6 +384,12 @@ func (c *LeveledCompactor) Write(dest string, b BlockReader, mint, maxt int64) (
meta.Compaction.Level = 1
meta.Compaction.Sources = []ulid.ULID{uid}
if parent != nil {
meta.Compaction.Parents = []BlockDesc{
{ULID: parent.ULID, MinTime: parent.MinTime, MaxTime: parent.MaxTime},
}
}
err := c.write(dest, meta, b)
if err != nil {
return uid, err

167
db.go
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@ -267,17 +267,9 @@ func (db *DB) run() {
case <-db.compactc:
db.metrics.compactionsTriggered.Inc()
_, err1 := db.retentionCutoff()
if err1 != nil {
level.Error(db.logger).Log("msg", "retention cutoff failed", "err", err1)
}
_, err2 := db.compact()
if err2 != nil {
level.Error(db.logger).Log("msg", "compaction failed", "err", err2)
}
if err1 != nil || err2 != nil {
_, err := db.compact()
if err != nil {
level.Error(db.logger).Log("msg", "compaction failed", "err", err)
backoff = exponential(backoff, 1*time.Second, 1*time.Minute)
} else {
backoff = 0
@ -289,19 +281,9 @@ func (db *DB) run() {
}
}
func (db *DB) retentionCutoff() (b bool, err error) {
defer func() {
if !b && err == nil {
// no data had to be cut off.
return
}
db.metrics.cutoffs.Inc()
if err != nil {
db.metrics.cutoffsFailed.Inc()
}
}()
func (db *DB) beyondRetention(meta *BlockMeta) bool {
if db.opts.RetentionDuration == 0 {
return false, nil
return false
}
db.mtx.RLock()
@ -309,23 +291,13 @@ func (db *DB) retentionCutoff() (b bool, err error) {
db.mtx.RUnlock()
if len(blocks) == 0 {
return false, nil
return false
}
last := blocks[len(db.blocks)-1]
mint := last.Meta().MaxTime - int64(db.opts.RetentionDuration)
dirs, err := retentionCutoffDirs(db.dir, mint)
if err != nil {
return false, err
}
// This will close the dirs and then delete the dirs.
if len(dirs) > 0 {
return true, db.reload(dirs...)
}
return false, nil
return meta.MaxTime < mint
}
// Appender opens a new appender against the database.
@ -354,6 +326,13 @@ func (a dbAppender) Commit() error {
return err
}
// Compact data if possible. After successful compaction blocks are reloaded
// which will also trigger blocks to be deleted that fall out of the retention
// window.
// If no blocks are compacted, the retention window state doesn't change. Thus,
// this is sufficient to reliably delete old data.
// Old blocks are only deleted on reload based on the new block's parent information.
// See DB.reload documentation for further information.
func (db *DB) compact() (changes bool, err error) {
db.cmtx.Lock()
defer db.cmtx.Unlock()
@ -383,7 +362,7 @@ func (db *DB) compact() (changes bool, err error) {
mint: mint,
maxt: maxt,
}
if _, err = db.compactor.Write(db.dir, head, mint, maxt); err != nil {
if _, err = db.compactor.Write(db.dir, head, mint, maxt, nil); err != nil {
return changes, errors.Wrap(err, "persist head block")
}
changes = true
@ -418,7 +397,7 @@ func (db *DB) compact() (changes bool, err error) {
changes = true
runtime.GC()
if err := db.reload(plan...); err != nil {
if err := db.reload(); err != nil {
return changes, errors.Wrap(err, "reload blocks")
}
runtime.GC()
@ -427,39 +406,6 @@ func (db *DB) compact() (changes bool, err error) {
return changes, nil
}
// retentionCutoffDirs returns all directories of blocks in dir that are strictly
// before mint.
func retentionCutoffDirs(dir string, mint int64) ([]string, error) {
df, err := fileutil.OpenDir(dir)
if err != nil {
return nil, errors.Wrapf(err, "open directory")
}
defer df.Close()
dirs, err := blockDirs(dir)
if err != nil {
return nil, errors.Wrapf(err, "list block dirs %s", dir)
}
delDirs := []string{}
for _, dir := range dirs {
meta, err := readMetaFile(dir)
if err != nil {
return nil, errors.Wrapf(err, "read block meta %s", dir)
}
// The first block we encounter marks that we crossed the boundary
// of deletable blocks.
if meta.MaxTime >= mint {
break
}
delDirs = append(delDirs, dir)
}
return delDirs, nil
}
func (db *DB) getBlock(id ulid.ULID) (*Block, bool) {
for _, b := range db.blocks {
if b.Meta().ULID == id {
@ -469,18 +415,10 @@ func (db *DB) getBlock(id ulid.ULID) (*Block, bool) {
return nil, false
}
func stringsContain(set []string, elem string) bool {
for _, e := range set {
if elem == e {
return true
}
}
return false
}
// reload on-disk blocks and trigger head truncation if new blocks appeared. It takes
// a list of block directories which should be deleted during reload.
func (db *DB) reload(deleteable ...string) (err error) {
// Blocks that are obsolete due to replacement or retention will be deleted.
func (db *DB) reload() (err error) {
defer func() {
if err != nil {
db.metrics.reloadsFailed.Inc()
@ -492,21 +430,58 @@ func (db *DB) reload(deleteable ...string) (err error) {
if err != nil {
return errors.Wrap(err, "find blocks")
}
// We delete old blocks that have been superseded by new ones by gathering all parents
// from existing blocks. Those parents all have newer replacements and can be safely deleted
// after we loaded the other blocks.
// This makes us resilient against the process crashing towards the end of a compaction.
// Creation of a new block and deletion of its parents cannot happen atomically. By creating
// blocks with their parents, we can pick up the deletion where it left off during a crash.
var (
blocks []*Block
exist = map[ulid.ULID]struct{}{}
corrupted = map[ulid.ULID]error{}
opened = map[ulid.ULID]struct{}{}
deleteable = map[ulid.ULID]struct{}{}
)
for _, dir := range dirs {
meta, err := readMetaFile(dir)
if err != nil {
// The block was potentially in the middle of being deleted during a crash.
// Skip it since we may delete it properly further down again.
level.Warn(db.logger).Log("msg", "read meta information", "err", err, "dir", dir)
ulid, err2 := ulid.Parse(filepath.Base(dir))
if err2 != nil {
level.Error(db.logger).Log("msg", "not a block dir", "dir", dir)
continue
}
corrupted[ulid] = err
continue
}
if db.beyondRetention(meta) {
deleteable[meta.ULID] = struct{}{}
continue
}
for _, b := range meta.Compaction.Parents {
deleteable[b.ULID] = struct{}{}
}
}
// Blocks we failed to open should all be those we are want to delete anyway.
for c, err := range corrupted {
if _, ok := deleteable[c]; !ok {
return errors.Wrapf(err, "unexpected corrupted block %s", c)
}
}
// Load new blocks into memory.
for _, dir := range dirs {
meta, err := readMetaFile(dir)
if err != nil {
return errors.Wrapf(err, "read meta information %s", dir)
}
// If the block is pending for deletion, don't add it to the new block set.
if stringsContain(deleteable, dir) {
// Don't load blocks that are scheduled for deletion.
if _, ok := deleteable[meta.ULID]; ok {
continue
}
// See if we already have the block in memory or open it otherwise.
b, ok := db.getBlock(meta.ULID)
if !ok {
b, err = OpenBlock(dir, db.chunkPool)
@ -514,9 +489,8 @@ func (db *DB) reload(deleteable ...string) (err error) {
return errors.Wrapf(err, "open block %s", dir)
}
}
blocks = append(blocks, b)
exist[meta.ULID] = struct{}{}
opened[meta.ULID] = struct{}{}
}
sort.Slice(blocks, func(i, j int) bool {
return blocks[i].Meta().MinTime < blocks[j].Meta().MinTime
@ -533,15 +507,19 @@ func (db *DB) reload(deleteable ...string) (err error) {
db.blocks = blocks
db.mtx.Unlock()
// Drop old blocks from memory.
for _, b := range oldBlocks {
if _, ok := exist[b.Meta().ULID]; ok {
if _, ok := opened[b.Meta().ULID]; ok {
continue
}
if err := b.Close(); err != nil {
level.Warn(db.logger).Log("msg", "closing block failed", "err", err)
}
if err := os.RemoveAll(b.Dir()); err != nil {
level.Warn(db.logger).Log("msg", "deleting block failed", "err", err)
}
// Delete all obsolete blocks. None of them are opened any longer.
for ulid := range deleteable {
if err := os.RemoveAll(filepath.Join(db.dir, ulid.String())); err != nil {
return errors.Wrapf(err, "delete obsolete block %s", ulid)
}
}
@ -765,7 +743,7 @@ func (db *DB) Snapshot(dir string, withHead bool) error {
if !withHead {
return nil
}
_, err := db.compactor.Write(dir, db.head, db.head.MinTime(), db.head.MaxTime())
_, err := db.compactor.Write(dir, db.head, db.head.MinTime(), db.head.MaxTime(), nil)
return errors.Wrap(err, "snapshot head block")
}
@ -859,22 +837,15 @@ func (db *DB) CleanTombstones() (err error) {
blocks := db.blocks[:]
db.mtx.RUnlock()
deletable := []string{}
for _, b := range blocks {
if uid, er := b.CleanTombstones(db.Dir(), db.compactor); er != nil {
err = errors.Wrapf(er, "clean tombstones: %s", b.Dir())
return err
} else if uid != nil { // New block was created.
deletable = append(deletable, b.Dir())
newUIDs = append(newUIDs, *uid)
}
}
if len(deletable) == 0 {
return nil
}
return errors.Wrap(db.reload(deletable...), "reload blocks")
return errors.Wrap(db.reload(), "reload blocks")
}
func intervalOverlap(amin, amax, bmin, bmax int64) bool {

8
db_test.go
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@ -842,7 +842,7 @@ type mockCompactorFailing struct {
func (*mockCompactorFailing) Plan(dir string) ([]string, error) {
return nil, nil
}
func (c *mockCompactorFailing) Write(dest string, b BlockReader, mint, maxt int64) (ulid.ULID, error) {
func (c *mockCompactorFailing) Write(dest string, b BlockReader, mint, maxt int64, parent *BlockMeta) (ulid.ULID, error) {
if len(c.blocks) >= c.max {
return ulid.ULID{}, fmt.Errorf("the compactor already did the maximum allowed blocks so it is time to fail")
}
@ -925,10 +925,8 @@ func TestDB_Retention(t *testing.T) {
testutil.Equals(t, 2, len(db.blocks))
// Now call retention.
changes, err := db.retentionCutoff()
testutil.Ok(t, err)
testutil.Assert(t, changes, "there should be changes")
// Reload blocks, which should drop blocks beyond the retention boundary.
testutil.Ok(t, db.reload())
testutil.Equals(t, 1, len(db.blocks))
testutil.Equals(t, int64(100), db.blocks[0].meta.MaxTime) // To verify its the right block.
}

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