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Improve chunk and chunkDesc loading.

Browse source 
Also, clean up some things in the code (especially introduction of the
chunkLenWithHeader constant to avoid the same expression all over the place).

Benchmark results:

BEFORE
BenchmarkLoadChunksSequentially     5000            283580 ns/op          152143 B/op        312 allocs/op
BenchmarkLoadChunksRandomly        20000             82936 ns/op           39310 B/op         99 allocs/op
BenchmarkLoadChunkDescs            10000            110833 ns/op           15092 B/op        345 allocs/op

AFTER
BenchmarkLoadChunksSequentially    10000            146785 ns/op          152285 B/op        315 allocs/op
BenchmarkLoadChunksRandomly        20000             67598 ns/op           39438 B/op        103 allocs/op
BenchmarkLoadChunkDescs            20000             99631 ns/op           12636 B/op        192 allocs/op

Note that everything is obviously loaded from the page cache (as the
benchmark runs thousands of times with very small series files). In a
real-world scenario, I expect a larger impact, as the disk operations
will more often actually hit the disk. To load ~50 sequential chunks,
this reduces the iops from 100 seeks and 100 reads to 1 seek and 1
read.
This commit is contained in:
beorn7 2015-04-13 20:20:26 +02:00
parent c563398c68
commit b02d900e61
5 changed files with 64 additions and 45 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
storage/local/chunk.go
View file

@ -192,6 +192,7 @@ type chunk interface {
newIterator() chunkIterator
marshal(io.Writer) error
unmarshal(io.Reader) error
unmarshalFromBuf([]byte)
encoding() chunkEncoding
// values returns a channel, from which all sample values in the chunk
// can be received in order. The channel is closed after the last

4
storage/local/crashrecovery.go
View file

@ -191,8 +191,8 @@ func (p *persistence) sanitizeSeries(
return fp, false
}
bytesToTrim := fi.Size() % int64(chunkLen+chunkHeaderLen)
chunksInFile := int(fi.Size()) / (chunkLen + chunkHeaderLen)
bytesToTrim := fi.Size() % int64(chunkLenWithHeader)
chunksInFile := int(fi.Size()) / chunkLenWithHeader
modTime := fi.ModTime()
if bytesToTrim != 0 {
glog.Warningf(

16
storage/local/delta.go
View file

@ -223,18 +223,20 @@ func (c deltaEncodedChunk) marshal(w io.Writer) error {
// unmarshal implements chunk.
func (c *deltaEncodedChunk) unmarshal(r io.Reader) error {
*c = (*c)[:cap(*c)]
readBytes := 0
for readBytes < len(*c) {
n, err := r.Read((*c)[readBytes:])
if err != nil {
return err
}
readBytes += n
if _, err := io.ReadFull(r, *c); err != nil {
return err
}
*c = (*c)[:binary.LittleEndian.Uint16((*c)[deltaHeaderBufLenOffset:])]
return nil
}
// unmarshalFromBuf implements chunk.
func (c *deltaEncodedChunk) unmarshalFromBuf(buf []byte) {
*c = (*c)[:cap(*c)]
copy(*c, buf)
*c = (*c)[:binary.LittleEndian.Uint16((*c)[deltaHeaderBufLenOffset:])]
}
// values implements chunk.
func (c deltaEncodedChunk) values() <-chan *metric.SamplePair {
n := c.len()

16
storage/local/doubledelta.go
View file

@ -231,18 +231,20 @@ func (c doubleDeltaEncodedChunk) marshal(w io.Writer) error {
// unmarshal implements chunk.
func (c *doubleDeltaEncodedChunk) unmarshal(r io.Reader) error {
*c = (*c)[:cap(*c)]
readBytes := 0
for readBytes < len(*c) {
n, err := r.Read((*c)[readBytes:])
if err != nil {
return err
}
readBytes += n
if _, err := io.ReadFull(r, *c); err != nil {
return err
}
*c = (*c)[:binary.LittleEndian.Uint16((*c)[doubleDeltaHeaderBufLenOffset:])]
return nil
}
// unmarshalFromBuf implements chunk.
func (c *doubleDeltaEncodedChunk) unmarshalFromBuf(buf []byte) {
*c = (*c)[:cap(*c)]
copy(*c, buf)
*c = (*c)[:binary.LittleEndian.Uint16((*c)[doubleDeltaHeaderBufLenOffset:])]
}
// values implements chunk.
func (c doubleDeltaEncodedChunk) values() <-chan *metric.SamplePair {
n := c.len()

72
storage/local/persistence.go
View file

@ -63,13 +63,19 @@ const (
chunkHeaderTypeOffset = 0
chunkHeaderFirstTimeOffset = 1
chunkHeaderLastTimeOffset = 9
chunkLenWithHeader = chunkLen + chunkHeaderLen
chunkMaxBatchSize = 64 // How many chunks to load at most in one batch.
indexingMaxBatchSize = 1024 * 1024
indexingBatchTimeout = 500 * time.Millisecond // Commit batch when idle for that long.
indexingQueueCapacity = 1024 * 16
)
var fpLen = len(clientmodel.Fingerprint(0).String()) // Length of a fingerprint as string.
var (
fpLen = len(clientmodel.Fingerprint(0).String()) // Length of a fingerprint as string.
byteBufPool = sync.Pool{New: func() interface{} { return make([]byte, 0, 3*chunkLenWithHeader) }}
)
const (
flagHeadChunkPersisted byte = 1 << iota
@ -377,28 +383,37 @@ func (p *persistence) loadChunks(fp clientmodel.Fingerprint, indexes []int, inde
defer f.Close()
chunks := make([]chunk, 0, len(indexes))
typeBuf := make([]byte, 1)
for _, idx := range indexes {
_, err := f.Seek(offsetForChunkIndex(idx+indexOffset), os.SEEK_SET)
if err != nil {
buf := byteBufPool.Get().([]byte)
defer func() {
byteBufPool.Put(buf)
}()
for i := 0; i < len(indexes); i++ {
// This loads chunks in batches. A batch is a streak of
// consecutive chunks, read from disk in one go.
batchSize := 1
if _, err := f.Seek(offsetForChunkIndex(indexes[i]+indexOffset), os.SEEK_SET); err != nil {
return nil, err
}
n, err := f.Read(typeBuf)
if err != nil {
return nil, err
for ; batchSize < chunkMaxBatchSize &&
i+1 < len(indexes) &&
indexes[i]+1 == indexes[i+1]; i, batchSize = i+1, batchSize+1 {
}
if n != 1 {
panic("read returned != 1 bytes")
readSize := batchSize * chunkLenWithHeader
if cap(buf) < readSize {
buf = make([]byte, readSize)
}
buf = buf[:readSize]
_, err = f.Seek(chunkHeaderLen-1, os.SEEK_CUR)
if err != nil {
if _, err := io.ReadFull(f, buf); err != nil {
return nil, err
}
chunk := newChunkForEncoding(chunkEncoding(typeBuf[0]))
chunk.unmarshal(f)
chunks = append(chunks, chunk)
for c := 0; c < batchSize; c++ {
chunk := newChunkForEncoding(chunkEncoding(buf[c*chunkLenWithHeader+chunkHeaderTypeOffset]))
chunk.unmarshalFromBuf(buf[c*chunkLenWithHeader+chunkHeaderLen:])
chunks = append(chunks, chunk)
}
}
chunkOps.WithLabelValues(load).Add(float64(len(chunks)))
atomic.AddInt64(&numMemChunks, int64(len(chunks)))
@ -422,24 +437,23 @@ func (p *persistence) loadChunkDescs(fp clientmodel.Fingerprint, beforeTime clie
if err != nil {
return nil, err
}
totalChunkLen := chunkHeaderLen + chunkLen
if fi.Size()%int64(totalChunkLen) != 0 {
if fi.Size()%int64(chunkLenWithHeader) != 0 {
p.setDirty(true)
return nil, fmt.Errorf(
"size of series file for fingerprint %v is %d, which is not a multiple of the chunk length %d",
fp, fi.Size(), totalChunkLen,
fp, fi.Size(), chunkLenWithHeader,
)
}
numChunks := int(fi.Size()) / totalChunkLen
numChunks := int(fi.Size()) / chunkLenWithHeader
cds := make([]*chunkDesc, 0, numChunks)
chunkTimesBuf := make([]byte, 16)
for i := 0; i < numChunks; i++ {
_, err := f.Seek(offsetForChunkIndex(i)+chunkHeaderFirstTimeOffset, os.SEEK_SET)
if err != nil {
return nil, err
}
chunkTimesBuf := make([]byte, 16)
_, err = io.ReadAtLeast(f, chunkTimesBuf, 16)
if err != nil {
return nil, err
@ -799,7 +813,7 @@ func (p *persistence) loadSeriesMapAndHeads() (sm *seriesMap, chunksToPersist in
}
chunk := newChunkForEncoding(chunkEncoding(encoding))
if err := chunk.unmarshal(r); err != nil {
glog.Warning("Could not decode chunk type:", err)
glog.Warning("Could not decode chunk:", err)
p.dirty = true
return sm, chunksToPersist, nil
}
@ -900,7 +914,7 @@ func (p *persistence) dropAndPersistChunks(
return
}
headerBuf := make([]byte, chunkHeaderLen)
_, err = io.ReadAtLeast(f, headerBuf, chunkHeaderLen)
_, err = io.ReadFull(f, headerBuf)
if err == io.EOF {
// We ran into the end of the file without finding any chunks that should
// be kept. Remove the whole file.
@ -960,7 +974,7 @@ func (p *persistence) dropAndPersistChunks(
if err != nil {
return
}
offset = int(written / (chunkHeaderLen + chunkLen))
offset = int(written / chunkLenWithHeader)
if len(chunks) > 0 {
if err = writeChunks(temp, chunks); err != nil {
@ -983,7 +997,7 @@ func (p *persistence) deleteSeriesFile(fp clientmodel.Fingerprint) (int, error)
if err != nil {
return -1, err
}
numChunks := int(fi.Size() / (chunkHeaderLen + chunkLen))
numChunks := int(fi.Size() / chunkLenWithHeader)
if err := os.Remove(fname); err != nil {
return -1, err
}
@ -1366,17 +1380,17 @@ loop:
}
func offsetForChunkIndex(i int) int64 {
return int64(i * (chunkHeaderLen + chunkLen))
return int64(i * chunkLenWithHeader)
}
func chunkIndexForOffset(offset int64) (int, error) {
if int(offset)%(chunkHeaderLen+chunkLen) != 0 {
if int(offset)%chunkLenWithHeader != 0 {
return -1, fmt.Errorf(
"offset %d is not a multiple of on-disk chunk length %d",
offset, chunkHeaderLen+chunkLen,
offset, chunkLenWithHeader,
)
}
return int(offset) / (chunkHeaderLen + chunkLen), nil
return int(offset) / chunkLenWithHeader, nil
}
func writeChunkHeader(w io.Writer, c chunk) error {
@ -1389,7 +1403,7 @@ func writeChunkHeader(w io.Writer, c chunk) error {
}
func writeChunks(w io.Writer, chunks []chunk) error {
b := bufio.NewWriterSize(w, len(chunks)*(chunkHeaderLen+chunkLen))
b := bufio.NewWriterSize(w, len(chunks)*chunkLenWithHeader)
for _, chunk := range chunks {
if err := writeChunkHeader(b, chunk); err != nil {
return err