Do not use syncPool for chunks when querying

The only time any chunks are currently put into the syncPool is during a
compaction. This means that during almost all normal operation a new
chunk is still being created, along with the extra overhead of going
through the syncPool Get process.

Signed-off-by: Chris Marchbanks <[email protected]>

chunks/chunks.go

@@ -310,9 +310,6 @@ func newReader(bs []ByteSlice, cs []io.Closer, pool chunkenc.Pool) (*Reader, err
 
 // NewReader returns a new chunk reader against the given byte slices.
 func NewReader(bs []ByteSlice, pool chunkenc.Pool) (*Reader, error) {
-	if pool == nil {
-		pool = chunkenc.NewPool()
-	}
 	return newReader(bs, nil, pool)
 }
 
@@ -323,9 +320,6 @@ func NewDirReader(dir string, pool chunkenc.Pool) (*Reader, error) {
 	if err != nil {
 		return nil, err
 	}
-	if pool == nil {
-		pool = chunkenc.NewPool()
-	}
 
 	var bs []ByteSlice
 	var cs []io.Closer
@@ -368,6 +362,9 @@ func (s *Reader) Chunk(ref uint64) (chunkenc.Chunk, error) {
 	}
 	r = b.Range(off+n, off+n+int(l))
 
+	if s.pool == nil {
+		return chunkenc.FromData(chunkenc.Encoding(r[0]), r[1:1+l])
+	}
 	return s.pool.Get(chunkenc.Encoding(r[0]), r[1:1+l])
 }
 

db.go

@@ -99,7 +99,6 @@ type DB struct {
 	logger    log.Logger
 	metrics   *dbMetrics
 	opts      *Options
-	chunkPool chunkenc.Pool
 	compactor Compactor
 
 	// Mutex for that must be held when modifying the general block layout.
@@ -233,7 +232,6 @@ func Open(dir string, l log.Logger, r prometheus.Registerer, opts *Options) (db
 		donec:              make(chan struct{}),
 		stopc:              make(chan struct{}),
 		compactionsEnabled: true,
-		chunkPool:          chunkenc.NewPool(),
 	}
 	db.metrics = newDBMetrics(db, r)
 
@@ -249,7 +247,7 @@ func Open(dir string, l log.Logger, r prometheus.Registerer, opts *Options) (db
 		db.lockf = lockf
 	}
 
-	db.compactor, err = NewLeveledCompactor(r, l, opts.BlockRanges, db.chunkPool)
+	db.compactor, err = NewLeveledCompactor(r, l, opts.BlockRanges, chunkenc.NewPool())
 	if err != nil {
 		return nil, errors.Wrap(err, "create leveled compactor")
 	}
@@ -521,7 +519,7 @@ func (db *DB) reload() (err error) {
 		// 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)
+			b, err = OpenBlock(dir, nil)
 			if err != nil {
 				return errors.Wrapf(err, "open block %s", dir)
 			}