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Integrate new WAL and checkpoints

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Remove the old WAL and drop in the new one

Signed-off-by: Fabian Reinartz <freinartz@google.com>
This commit is contained in:
Fabian Reinartz 2018-05-17 09:04:32 -04:00
parent 008399a6e0
commit def912ce0e
4 changed files with 285 additions and 114 deletions
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6
checkpoint_test.go
View file

@ -15,7 +15,6 @@
package tsdb
import (
"fmt"
"io/ioutil"
"os"
"path/filepath"
@ -82,7 +81,7 @@ func TestDeleteCheckpoints(t *testing.T) {
func TestCheckpoint(t *testing.T) {
dir, err := ioutil.TempDir("", "test_checkpoint")
testutil.Ok(t, err)
fmt.Println(dir)
defer os.RemoveAll(dir)
var enc RecordEncoder
// Create a dummy segment to bump the initial number.
@ -138,11 +137,10 @@ func TestCheckpoint(t *testing.T) {
}
testutil.Ok(t, w.Close())
stats, err = Checkpoint(nil, w, 100, 106, func(x uint64) bool {
_, err = Checkpoint(nil, w, 100, 106, func(x uint64) bool {
return x%2 == 0
}, last/2)
testutil.Ok(t, err)
testutil.Equals(t, 106, stats.HighSegment)
// Only the new checkpoint should be left.
files, err := fileutil.ReadDir(dir)

7
db.go
View file

@ -37,6 +37,7 @@ import (
"github.com/prometheus/tsdb/chunkenc"
"github.com/prometheus/tsdb/fileutil"
"github.com/prometheus/tsdb/labels"
"github.com/prometheus/tsdb/wal"
"golang.org/x/sync/errgroup"
)
@ -221,18 +222,18 @@ func Open(dir string, l log.Logger, r prometheus.Registerer, opts *Options) (db
return nil, errors.Wrap(err, "create leveled compactor")
}
wal, err := OpenSegmentWAL(filepath.Join(dir, "wal"), l, opts.WALFlushInterval, r)
wlog, err := wal.New(l, r, filepath.Join(dir, "wal"))
if err != nil {
return nil, err
}
db.head, err = NewHead(r, l, wal, opts.BlockRanges[0])
db.head, err = NewHead(r, l, wlog, opts.BlockRanges[0])
if err != nil {
return nil, err
}
if err := db.reload(); err != nil {
return nil, err
}
if err := db.head.ReadWAL(); err != nil {
if err := db.head.Init(); err != nil {
return nil, errors.Wrap(err, "read WAL")
}

270
head.go
View file

@ -15,6 +15,7 @@ package tsdb
import (
"math"
"path/filepath"
"runtime"
"sort"
"strings"
@ -30,6 +31,7 @@ import (
"github.com/prometheus/tsdb/chunks"
"github.com/prometheus/tsdb/index"
"github.com/prometheus/tsdb/labels"
"github.com/prometheus/tsdb/wal"
)
var (
@ -53,9 +55,10 @@ var (
type Head struct {
chunkRange int64
metrics *headMetrics
wal WAL
wal *wal.WAL
logger log.Logger
appendPool sync.Pool
bytesPool sync.Pool
minTime, maxTime int64
lastSeriesID uint64
@ -169,13 +172,10 @@ func newHeadMetrics(h *Head, r prometheus.Registerer) *headMetrics {
}
// NewHead opens the head block in dir.
func NewHead(r prometheus.Registerer, l log.Logger, wal WAL, chunkRange int64) (*Head, error) {
func NewHead(r prometheus.Registerer, l log.Logger, wal *wal.WAL, chunkRange int64) (*Head, error) {
if l == nil {
l = log.NewNopLogger()
}
if wal == nil {
wal = NopWAL()
}
if chunkRange < 1 {
return nil, errors.Errorf("invalid chunk range %d", chunkRange)
}
@ -206,6 +206,8 @@ func (h *Head) processWALSamples(
) (unknownRefs uint64) {
defer close(output)
maxt := h.MaxTime()
for samples := range input {
for _, s := range samples {
if s.T < mint || s.Ref%total != partition {
@ -221,17 +223,27 @@ func (h *Head) processWALSamples(
h.metrics.chunksCreated.Inc()
h.metrics.chunks.Inc()
}
if s.T > maxt {
maxt = s.T
}
}
output <- samples
}
for {
ht := h.MaxTime()
if maxt <= ht {
break
}
if atomic.CompareAndSwapInt64(&h.maxTime, ht, maxt) {
break
}
}
return unknownRefs
}
// ReadWAL initializes the head by consuming the write ahead log.
func (h *Head) ReadWAL() error {
defer h.postings.EnsureOrder()
r := h.wal.Reader()
func (h *Head) loadWAL(r *wal.Reader) error {
mint := h.MinTime()
// Track number of samples that referenced a series we don't know about
@ -263,49 +275,71 @@ func (h *Head) ReadWAL() error {
input = output
}
// TODO(fabxc): series entries spread between samples can starve the sample workers.
// Even with bufferd channels, this can impact startup time with lots of series churn.
// We must not paralellize series creation itself but could make the indexing asynchronous.
seriesFunc := func(series []RefSeries) {
for _, s := range series {
h.getOrCreateWithID(s.Ref, s.Labels.Hash(), s.Labels)
var (
dec RecordDecoder
series []RefSeries
samples []RefSample
tstones []Stone
)
for r.Next() {
series, samples, tstones = series[:0], samples[:0], tstones[:0]
rec := r.Record()
if h.lastSeriesID < s.Ref {
h.lastSeriesID = s.Ref
switch dec.Type(rec) {
case RecordSeries:
series, err := dec.Series(rec, series)
if err != nil {
return errors.Wrap(err, "decode series")
}
}
}
samplesFunc := func(samples []RefSample) {
// We split up the samples into chunks of 5000 samples or less.
// With O(300 * #cores) in-flight sample batches, large scrapes could otherwise
// cause thousands of very large in flight buffers occupying large amounts
// of unused memory.
for len(samples) > 0 {
n := 5000
if len(samples) < n {
n = len(samples)
}
var buf []RefSample
select {
case buf = <-input:
default:
}
firstInput <- append(buf[:0], samples[:n]...)
samples = samples[n:]
}
}
deletesFunc := func(stones []Stone) {
for _, s := range stones {
for _, itv := range s.intervals {
if itv.Maxt < mint {
continue
for _, s := range series {
h.getOrCreateWithID(s.Ref, s.Labels.Hash(), s.Labels)
if h.lastSeriesID < s.Ref {
h.lastSeriesID = s.Ref
}
h.tombstones.addInterval(s.ref, itv)
}
case RecordSamples:
samples, err := dec.Samples(rec, samples)
if err != nil {
return errors.Wrap(err, "decode samples")
}
// We split up the samples into chunks of 5000 samples or less.
// With O(300 * #cores) in-flight sample batches, large scrapes could otherwise
// cause thousands of very large in flight buffers occupying large amounts
// of unused memory.
for len(samples) > 0 {
n := 5000
if len(samples) < n {
n = len(samples)
}
var buf []RefSample
select {
case buf = <-input:
default:
}
firstInput <- append(buf[:0], samples[:n]...)
samples = samples[n:]
}
case RecordTombstones:
tstones, err := dec.Tombstones(rec, tstones)
if err != nil {
return errors.Wrap(err, "decode tombstones")
}
for _, s := range tstones {
for _, itv := range s.intervals {
if itv.Maxt < mint {
continue
}
h.tombstones.addInterval(s.ref, itv)
}
}
default:
return errors.Errorf("invalid record type %v", dec.Type(rec))
}
}
err := r.Read(seriesFunc, samplesFunc, deletesFunc)
if r.Err() != nil {
return errors.Wrap(r.Err(), "read records")
}
// Signal termination to first worker and wait for last one to close its output channel.
close(firstInput)
@ -313,16 +347,58 @@ func (h *Head) ReadWAL() error {
}
wg.Wait()
if err != nil {
return errors.Wrap(err, "consume WAL")
}
if unknownRefs > 0 {
level.Warn(h.logger).Log("msg", "unknown series references in WAL samples", "count", unknownRefs)
level.Warn(h.logger).Log("msg", "unknown series references", "count", unknownRefs)
}
return nil
}
// Truncate removes all data before mint from the head block and truncates its WAL.
// Init loads data from the write ahead log and prepares the head for writes.
func (h *Head) Init() error {
defer h.postings.EnsureOrder()
if h.wal == nil {
return nil
}
// Backfill the checkpoint first if it exists.
cp, n, err := LastCheckpoint(h.wal.Dir())
if err != nil && err != ErrNotFound {
return errors.Wrap(err, "find last checkpoint")
}
if err == nil {
sr, err := wal.NewSegmentsReader(filepath.Join(h.wal.Dir(), cp))
if err != nil {
return errors.Wrap(err, "open checkpoint")
}
defer sr.Close()
// A corrupted checkpoint is a hard error for now and requires user
// intervention. There's likely little data that can be recovered anyway.
if err := h.loadWAL(wal.NewReader(sr)); err != nil {
return errors.Wrap(err, "backfill checkpoint")
}
n++
}
// Backfill segments from the last checkpoint onwards
sr, err := wal.NewSegmentsRangeReader(h.wal.Dir(), n, -1)
if err != nil {
return errors.Wrap(err, "open WAL segments")
}
defer sr.Close()
err = h.loadWAL(wal.NewReader(sr))
if err == nil {
return nil
}
if err := h.wal.Repair(err); err != nil {
return errors.Wrap(err, "repair corrupted WAL")
}
return nil
}
// Truncate removes old data before mint from the head.
func (h *Head) Truncate(mint int64) error {
initialize := h.MinTime() == math.MinInt64
@ -348,18 +424,37 @@ func (h *Head) Truncate(mint int64) error {
level.Info(h.logger).Log("msg", "head GC completed", "duration", time.Since(start))
h.metrics.gcDuration.Observe(time.Since(start).Seconds())
if h.wal == nil {
return nil
}
start = time.Now()
m, n, err := h.wal.Segments()
if err != nil {
return errors.Wrap(err, "get segment range")
}
n-- // Never consider last segment for checkpoint.
if n < 0 {
return nil // no segments yet.
}
// The lower third of segments should contain mostly obsolete samples.
// If we have too few segments, it's not worth checkpointing yet.
n = m + (n-m)/3
if n <= m {
return nil
}
keep := func(id uint64) bool {
return h.series.getByID(id) != nil
}
if err := h.wal.Truncate(mint, keep); err == nil {
level.Info(h.logger).Log("msg", "WAL truncation completed", "duration", time.Since(start))
} else {
level.Error(h.logger).Log("msg", "WAL truncation failed", "err", err, "duration", time.Since(start))
if _, err = Checkpoint(h.logger, h.wal, m, n, keep, mint); err != nil {
return errors.Wrap(err, "create checkpoint")
}
h.metrics.walTruncateDuration.Observe(time.Since(start).Seconds())
level.Info(h.logger).Log("msg", "WAL checkpoint complete",
"low", m, "high", n, "duration", time.Since(start))
return nil
}
@ -468,6 +563,18 @@ func (h *Head) putAppendBuffer(b []RefSample) {
h.appendPool.Put(b[:0])
}
func (h *Head) getBytesBuffer() []byte {
b := h.bytesPool.Get()
if b == nil {
return make([]byte, 0, 1024)
}
return b.([]byte)
}
func (h *Head) putBytesBuffer(b []byte) {
h.bytesPool.Put(b[:0])
}
type headAppender struct {
head *Head
mint, maxt int64
@ -520,15 +627,42 @@ func (a *headAppender) AddFast(ref uint64, t int64, v float64) error {
return nil
}
func (a *headAppender) log() error {
if a.head.wal == nil {
return nil
}
buf := a.head.getBytesBuffer()
defer func() { a.head.putBytesBuffer(buf) }()
var rec []byte
var enc RecordEncoder
if len(a.series) > 0 {
rec = enc.Series(a.series, buf)
buf = rec[:0]
if err := a.head.wal.Log(rec); err != nil {
return errors.Wrap(err, "log series")
}
}
if len(a.samples) > 0 {
rec = enc.Samples(a.samples, buf)
buf = rec[:0]
if err := a.head.wal.Log(rec); err != nil {
return errors.Wrap(err, "log samples")
}
}
return nil
}
func (a *headAppender) Commit() error {
defer a.head.metrics.activeAppenders.Dec()
defer a.head.putAppendBuffer(a.samples)
if err := a.head.wal.LogSeries(a.series); err != nil {
return err
}
if err := a.head.wal.LogSamples(a.samples); err != nil {
return errors.Wrap(err, "WAL log samples")
if err := a.log(); err != nil {
return errors.Wrap(err, "write to WAL")
}
total := len(a.samples)
@ -568,7 +702,8 @@ func (a *headAppender) Rollback() error {
// Series are created in the head memory regardless of rollback. Thus we have
// to log them to the WAL in any case.
return a.head.wal.LogSeries(a.series)
a.samples = nil
return a.log()
}
// Delete all samples in the range of [mint, maxt] for series that satisfy the given
@ -601,8 +736,12 @@ func (h *Head) Delete(mint, maxt int64, ms ...labels.Matcher) error {
if p.Err() != nil {
return p.Err()
}
if err := h.wal.LogDeletes(stones); err != nil {
return err
var enc RecordEncoder
if h.wal != nil {
if err := h.wal.Log(enc.Tombstones(stones, nil)); err != nil {
return err
}
}
for _, s := range stones {
h.tombstones.addInterval(s.ref, s.intervals[0])
@ -694,6 +833,9 @@ func (h *Head) MaxTime() int64 {
// Close flushes the WAL and closes the head.
func (h *Head) Close() error {
if h.wal == nil {
return nil
}
return h.wal.Close()
}

116
head_test.go
View file

@ -14,7 +14,9 @@
package tsdb
import (
"io/ioutil"
"math/rand"
"os"
"testing"
"github.com/prometheus/tsdb/chunkenc"
@ -22,6 +24,7 @@ import (
"github.com/prometheus/tsdb/index"
"github.com/prometheus/tsdb/labels"
"github.com/prometheus/tsdb/testutil"
"github.com/prometheus/tsdb/wal"
)
func BenchmarkCreateSeries(b *testing.B) {
@ -42,42 +45,50 @@ func BenchmarkCreateSeries(b *testing.B) {
}
}
type memoryWAL struct {
nopWAL
entries []interface{}
}
func (w *memoryWAL) LogSeries(s []RefSeries) error {
w.entries = append(w.entries, s)
return nil
}
func (w *memoryWAL) LogSamples(s []RefSample) error {
w.entries = append(w.entries, s)
return nil
}
func (w *memoryWAL) LogDeletes(s []Stone) error {
w.entries = append(w.entries, s)
return nil
}
func (w *memoryWAL) Reader() WALReader {
return w
}
func (w *memoryWAL) Read(series func([]RefSeries), samples func([]RefSample), deletes func([]Stone)) error {
for _, e := range w.entries {
switch v := e.(type) {
func populateTestWAL(t testing.TB, w *wal.WAL, recs []interface{}) {
var enc RecordEncoder
for _, r := range recs {
switch v := r.(type) {
case []RefSeries:
series(v)
testutil.Ok(t, w.Log(enc.Series(v, nil)))
case []RefSample:
samples(v)
testutil.Ok(t, w.Log(enc.Samples(v, nil)))
case []Stone:
deletes(v)
testutil.Ok(t, w.Log(enc.Tombstones(v, nil)))
}
}
return nil
}
func readTestWAL(t testing.TB, dir string) (recs []interface{}) {
sr, err := wal.NewSegmentsReader(dir)
testutil.Ok(t, err)
defer sr.Close()
var dec RecordDecoder
r := wal.NewReader(sr)
for r.Next() {
rec := r.Record()
switch dec.Type(rec) {
case RecordSeries:
series, err := dec.Series(rec, nil)
testutil.Ok(t, err)
recs = append(recs, series)
case RecordSamples:
samples, err := dec.Samples(rec, nil)
testutil.Ok(t, err)
recs = append(recs, samples)
case RecordTombstones:
tstones, err := dec.Tombstones(rec, nil)
testutil.Ok(t, err)
recs = append(recs, tstones)
default:
t.Fatalf("unknown record type")
}
}
testutil.Ok(t, r.Err())
return recs
}
func TestHead_ReadWAL(t *testing.T) {
@ -100,13 +111,19 @@ func TestHead_ReadWAL(t *testing.T) {
{Ref: 50, T: 101, V: 6},
},
}
wal := &memoryWAL{entries: entries}
dir, err := ioutil.TempDir("", "test_read_wal")
testutil.Ok(t, err)
defer os.RemoveAll(dir)
head, err := NewHead(nil, nil, wal, 1000)
w, err := wal.New(nil, nil, dir)
testutil.Ok(t, err)
populateTestWAL(t, w, entries)
head, err := NewHead(nil, nil, w, 1000)
testutil.Ok(t, err)
defer head.Close()
testutil.Ok(t, head.ReadWAL())
testutil.Ok(t, head.Init())
testutil.Equals(t, uint64(100), head.lastSeriesID)
s10 := head.series.getByID(10)
@ -259,13 +276,19 @@ func TestHeadDeleteSeriesWithoutSamples(t *testing.T) {
{Ref: 50, T: 90, V: 1},
},
}
wal := &memoryWAL{entries: entries}
dir, err := ioutil.TempDir("", "test_delete_series")
testutil.Ok(t, err)
defer os.RemoveAll(dir)
head, err := NewHead(nil, nil, wal, 1000)
w, err := wal.New(nil, nil, dir)
testutil.Ok(t, err)
populateTestWAL(t, w, entries)
head, err := NewHead(nil, nil, w, 1000)
testutil.Ok(t, err)
defer head.Close()
testutil.Ok(t, head.ReadWAL())
testutil.Ok(t, head.Init())
testutil.Ok(t, head.Delete(0, 100, labels.NewEqualMatcher("a", "1")))
}
@ -705,7 +728,7 @@ func TestMemSeries_append(t *testing.T) {
func TestGCChunkAccess(t *testing.T) {
// Put a chunk, select it. GC it and then access it.
h, err := NewHead(nil, nil, NopWAL(), 1000)
h, err := NewHead(nil, nil, nil, 1000)
testutil.Ok(t, err)
defer h.Close()
@ -745,7 +768,7 @@ func TestGCChunkAccess(t *testing.T) {
func TestGCSeriesAccess(t *testing.T) {
// Put a series, select it. GC it and then access it.
h, err := NewHead(nil, nil, NopWAL(), 1000)
h, err := NewHead(nil, nil, nil, 1000)
testutil.Ok(t, err)
defer h.Close()
@ -786,7 +809,12 @@ func TestGCSeriesAccess(t *testing.T) {
}
func TestHead_LogRollback(t *testing.T) {
w := &memoryWAL{}
dir, err := ioutil.TempDir("", "wal_rollback")
testutil.Ok(t, err)
defer os.RemoveAll(dir)
w, err := wal.New(nil, nil, dir)
testutil.Ok(t, err)
h, err := NewHead(nil, nil, w, 1000)
testutil.Ok(t, err)
@ -795,9 +823,11 @@ func TestHead_LogRollback(t *testing.T) {
testutil.Ok(t, err)
testutil.Ok(t, app.Rollback())
testutil.Equals(t, 1, len(w.entries))
recs := readTestWAL(t, w.Dir())
series, ok := w.entries[0].([]RefSeries)
testutil.Assert(t, ok, "expected series record but got %+v", w.entries[0])
testutil.Equals(t, 1, len(recs))
series, ok := recs[0].([]RefSeries)
testutil.Assert(t, ok, "expected series record but got %+v", recs[0])
testutil.Equals(t, series, []RefSeries{{Ref: 1, Labels: labels.FromStrings("a", "b")}})
}