Revert " Store `mmMaxTime` in same field as `seriesShard`"

Signed-off-by: Marco Pracucci <marco@pracucci.com>

tsdb/head.go

@@ -178,7 +178,6 @@ type HeadOptions struct {
 	WALReplayConcurrency int
 
 	// EnableSharding enables ShardedPostings() support in the Head.
-	// EnableSharding is temporarily disabled during Init().
 	EnableSharding bool
 }
 
@@ -610,7 +609,7 @@ const cardinalityCacheExpirationTime = time.Duration(30) * time.Second
 // Init loads data from the write ahead log and prepares the head for writes.
 // It should be called before using an appender so that it
 // limits the ingested samples to the head min valid time.
-func (h *Head) Init(minValidTime int64) (err error) {
+func (h *Head) Init(minValidTime int64) error {
 	h.minValidTime.Store(minValidTime)
 	defer func() {
 		h.postings.EnsureOrder(h.opts.WALReplayConcurrency)
@@ -624,24 +623,6 @@ func (h *Head) Init(minValidTime int64) (err error) {
 		}
 	}()
 
-	// If sharding is enabled, disable it while initializing, and calculate the shards later.
-	// We're going to use that field for other purposes during WAL replay,
-	// so we don't want to waste time on calculating the shard that we're going to lose anyway.
-	if h.opts.EnableSharding {
-		h.opts.EnableSharding = false
-		defer func() {
-			h.opts.EnableSharding = true
-			if err == nil {
-				// No locking is needed here as nobody should be writing while we're in Init.
-				for _, stripe := range h.series.series {
-					for _, s := range stripe {
-						s.shardHashOrMemoryMappedMaxTime = labels.StableHash(s.lset)
-					}
-				}
-			}
-		}()
-	}
-
 	level.Info(h.logger).Log("msg", "Replaying on-disk memory mappable chunks if any")
 	start := time.Now()
 
@@ -702,6 +683,7 @@ func (h *Head) Init(minValidTime int64) (err error) {
 		mmappedChunks    map[chunks.HeadSeriesRef][]*mmappedChunk
 		oooMmappedChunks map[chunks.HeadSeriesRef][]*mmappedChunk
 		lastMmapRef      chunks.ChunkDiskMapperRef
+		err              error
 
 		mmapChunkReplayDuration time.Duration
 	)
@@ -2086,11 +2068,9 @@ type memSeries struct {
 	ref  chunks.HeadSeriesRef
 	meta *metadata.Metadata
 
-	// Series labels hash to use for sharding purposes.
-	// The value is always 0 when sharding has not been explicitly enabled in TSDB.
-	// While the WAL replay the value stored here is the max time of any mmapped chunk,
-	// and the shard hash is re-calculated after WAL replay is complete.
-	shardHashOrMemoryMappedMaxTime uint64
+	// Series labels hash to use for sharding purposes. The value is always 0 when sharding has not
+	// been explicitly enabled in TSDB.
+	shardHash uint64
 
 	// Everything after here should only be accessed with the lock held.
 	sync.Mutex
@@ -2115,6 +2095,8 @@ type memSeries struct {
 
 	ooo *memSeriesOOOFields
 
+	mmMaxTime int64 // Max time of any mmapped chunk, only used during WAL replay.
+
 	nextAt                           int64 // Timestamp at which to cut the next chunk.
 	histogramChunkHasComputedEndTime bool  // True if nextAt has been predicted for the current histograms chunk; false otherwise.
 	pendingCommit                    bool  // Whether there are samples waiting to be committed to this series.
@@ -2145,10 +2127,10 @@ type memSeriesOOOFields struct {
 
 func newMemSeries(lset labels.Labels, id chunks.HeadSeriesRef, shardHash uint64, isolationDisabled bool) *memSeries {
 	s := &memSeries{
-		lset:                           lset,
-		ref:                            id,
-		nextAt:                         math.MinInt64,
-		shardHashOrMemoryMappedMaxTime: shardHash,
+		lset:      lset,
+		ref:       id,
+		nextAt:    math.MinInt64,
+		shardHash: shardHash,
 	}
 	if !isolationDisabled {
 		s.txs = newTxRing(0)
@@ -2236,12 +2218,6 @@ func (s *memSeries) truncateChunksBefore(mint int64, minOOOMmapRef chunks.ChunkD
 	return removedInOrder + removedOOO
 }
 
-// shardHash returns the shard hash of the series, only available after WAL replay.
-func (s *memSeries) shardHash() uint64 { return s.shardHashOrMemoryMappedMaxTime }
-
-// mmMaxTime returns the max time of any mmapped chunk in the series, only available during WAL replay.
-func (s *memSeries) mmMaxTime() int64 { return int64(s.shardHashOrMemoryMappedMaxTime) }
-
 // cleanupAppendIDsBelow cleans up older appendIDs. Has to be called after
 // acquiring lock.
 func (s *memSeries) cleanupAppendIDsBelow(bound uint64) {

tsdb/head_read.go

@@ -170,7 +170,7 @@ func (h *headIndexReader) ShardedPostings(p index.Postings, shardIndex, shardCou
 		}
 
 		// Check if the series belong to the shard.
-		if s.shardHash()%shardCount != shardIndex {
+		if s.shardHash%shardCount != shardIndex {
 			continue
 		}
 

tsdb/head_test.go

@@ -23,7 +23,6 @@ import (
 	"path"
 	"path/filepath"
 	"reflect"
-	"runtime/pprof"
 	"sort"
 	"strconv"
 	"strings"
@@ -90,43 +89,6 @@ func newTestHeadWithOptions(t testing.TB, compressWAL wlog.CompressionType, opts
 	return h, wal
 }
 
-// BenchmarkLoadRealWLs will be skipped unless the BENCHMARK_LOAD_REAL_WLS_DIR environment variable is set.
-// BENCHMARK_LOAD_REAL_WLS_DIR should be the folder where `wal` and `chunks_head` are located.
-// Optionally, BENCHMARK_LOAD_REAL_WLS_PROFILE can be set to a file path to write a CPU profile.
-func BenchmarkLoadRealWLs(b *testing.B) {
-	dir := os.Getenv("BENCHMARK_LOAD_REAL_WLS_DIR")
-	if dir == "" {
-		b.Skipped()
-	}
-
-	profileFile := os.Getenv("BENCHMARK_LOAD_REAL_WLS_PROFILE")
-	if profileFile != "" {
-		b.Logf("Will profile in %s", profileFile)
-		f, err := os.Create(profileFile)
-		require.NoError(b, err)
-		b.Cleanup(func() { f.Close() })
-		require.NoError(b, pprof.StartCPUProfile(f))
-		b.Cleanup(pprof.StopCPUProfile)
-	}
-
-	wal, err := wlog.New(nil, nil, filepath.Join(dir, "wal"), wlog.CompressionNone)
-	require.NoError(b, err)
-	b.Cleanup(func() { wal.Close() })
-
-	wbl, err := wlog.New(nil, nil, filepath.Join(dir, "wbl"), wlog.CompressionNone)
-	require.NoError(b, err)
-	b.Cleanup(func() { wbl.Close() })
-
-	// Load the WAL.
-	for i := 0; i < b.N; i++ {
-		opts := DefaultHeadOptions()
-		opts.ChunkDirRoot = dir
-		h, err := NewHead(nil, nil, wal, wbl, opts, nil)
-		require.NoError(b, err)
-		h.Init(0)
-	}
-}
-
 func BenchmarkCreateSeries(b *testing.B) {
 	series := genSeries(b.N, 10, 0, 0)
 	h, _ := newTestHead(b, 10000, wlog.CompressionNone, false)

tsdb/head_wal.go

@@ -435,8 +435,6 @@ Outer:
 	return nil
 }
 
-func minInt64() int64 { return math.MinInt64 }
-
 // resetSeriesWithMMappedChunks is only used during the WAL replay.
 func (h *Head) resetSeriesWithMMappedChunks(mSeries *memSeries, mmc, oooMmc []*mmappedChunk, walSeriesRef chunks.HeadSeriesRef) (overlapped bool) {
 	if mSeries.ref != walSeriesRef {
@@ -483,11 +481,10 @@ func (h *Head) resetSeriesWithMMappedChunks(mSeries *memSeries, mmc, oooMmc []*m
 	}
 	// Cache the last mmapped chunk time, so we can skip calling append() for samples it will reject.
 	if len(mmc) == 0 {
-		mSeries.shardHashOrMemoryMappedMaxTime = uint64(minInt64())
+		mSeries.mmMaxTime = math.MinInt64
 	} else {
-		mmMaxTime := mmc[len(mmc)-1].maxTime
-		mSeries.shardHashOrMemoryMappedMaxTime = uint64(mmMaxTime)
-		h.updateMinMaxTime(mmc[0].minTime, mmMaxTime)
+		mSeries.mmMaxTime = mmc[len(mmc)-1].maxTime
+		h.updateMinMaxTime(mmc[0].minTime, mSeries.mmMaxTime)
 	}
 	if len(oooMmc) != 0 {
 		// Mint and maxt can be in any chunk, they are not sorted.
@@ -588,7 +585,7 @@ func (wp *walSubsetProcessor) processWALSamples(h *Head, mmappedChunks, oooMmapp
 				unknownRefs++
 				continue
 			}
-			if s.T <= ms.mmMaxTime() {
+			if s.T <= ms.mmMaxTime {
 				continue
 			}
 			if _, chunkCreated := ms.append(s.T, s.V, 0, appendChunkOpts); chunkCreated {
@@ -617,7 +614,7 @@ func (wp *walSubsetProcessor) processWALSamples(h *Head, mmappedChunks, oooMmapp
 				unknownHistogramRefs++
 				continue
 			}
-			if s.t <= ms.mmMaxTime() {
+			if s.t <= ms.mmMaxTime {
 				continue
 			}
 			var chunkCreated bool