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optimize memory allocs during reconstruct (#4964)

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The reedsolomon library now avoids allocations during reconstruction.
This change exploits that to reduce memory allocs and GC preasure during
healing and reading.
This commit is contained in:
Andreas Auernhammer
2017-09-27 10:29:42 -07:00
committed by Dee Koder
parent 4879cd73f8
commit 02af37a394
8 changed files with 54 additions and 177 deletions
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26
cmd/erasure-readfile.go
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@@ -18,14 +18,12 @@ package cmd
import (
"io"
"github.com/minio/minio/pkg/bpool"
)
// ReadFile reads as much data as requested from the file under the given volume and path and writes the data to the provided writer.
// The algorithm and the keys/checksums are used to verify the integrity of the given file. ReadFile will read data from the given offset
// up to the given length. If parts of the file are corrupted ReadFile tries to reconstruct the data.
func (s ErasureStorage) ReadFile(writer io.Writer, volume, path string, offset, length int64, totalLength int64, checksums [][]byte, algorithm BitrotAlgorithm, blocksize int64, pool *bpool.BytePool) (f ErasureFileInfo, err error) {
func (s ErasureStorage) ReadFile(writer io.Writer, volume, path string, offset, length int64, totalLength int64, checksums [][]byte, algorithm BitrotAlgorithm, blocksize int64) (f ErasureFileInfo, err error) {
if offset < 0 || length < 0 {
return f, traceError(errUnexpected)
}
@@ -53,15 +51,20 @@ func (s ErasureStorage) ReadFile(writer io.Writer, volume, path string, offset,
chunksize := getChunkSize(blocksize, s.dataBlocks)
blocks := make([][]byte, len(s.disks))
for i := range blocks {
blocks[i] = make([]byte, chunksize)
}
for off := offset / blocksize; length > 0; off++ {
blockOffset := off * chunksize
pool.Reset()
if currentBlock := (offset + f.Size) / blocksize; currentBlock == lastBlock {
blocksize = totalLength % blocksize
chunksize = getChunkSize(blocksize, s.dataBlocks)
for i := range blocks {
blocks[i] = blocks[i][:chunksize]
}
}
err = s.readConcurrent(volume, path, blockOffset, chunksize, blocks, verifiers, errChans, pool)
err = s.readConcurrent(volume, path, blockOffset, blocks, verifiers, errChans)
if err != nil {
return f, traceError(errXLReadQuorum)
}
@@ -92,7 +95,7 @@ func (s ErasureStorage) ReadFile(writer io.Writer, volume, path string, offset,
func erasureCountMissingBlocks(blocks [][]byte, limit int) int {
missing := 0
for i := range blocks[:limit] {
if blocks[i] == nil {
if len(blocks[i]) == 0 {
missing++
}
}
@@ -101,15 +104,8 @@ func erasureCountMissingBlocks(blocks [][]byte, limit int) int {
// readConcurrent reads all requested data concurrently from the disks into blocks. It returns an error if
// too many disks failed while reading.
func (s *ErasureStorage) readConcurrent(volume, path string, offset int64, length int64, blocks [][]byte, verifiers []*BitrotVerifier, errChans []chan error, pool *bpool.BytePool) (err error) {
func (s *ErasureStorage) readConcurrent(volume, path string, offset int64, blocks [][]byte, verifiers []*BitrotVerifier, errChans []chan error) (err error) {
errs := make([]error, len(s.disks))
for i := range blocks {
blocks[i], err = pool.Get()
if err != nil {
return traceErrorf("failed to get new buffer from pool: %v", err)
}
blocks[i] = blocks[i][:length]
}
erasureReadBlocksConcurrent(s.disks[:s.dataBlocks], volume, path, offset, blocks[:s.dataBlocks], verifiers[:s.dataBlocks], errs[:s.dataBlocks], errChans[:s.dataBlocks])
missingDataBlocks := erasureCountMissingBlocks(blocks, s.dataBlocks)
@@ -145,7 +141,7 @@ func erasureReadBlocksConcurrent(disks []StorageAPI, volume, path string, offset
errors[i] = <-errChans[i] // blocks until the go routine 'i' is done - no data race
if errors[i] != nil {
disks[i] = OfflineDisk
blocks[i] = nil
blocks[i] = blocks[i][:0] // mark shard as missing
}
}
}