fix: checkpoint initialization gap on restarts

Entire-Checkpoint: 3f4d366b037c

Makefile

@@ -1,6 +1,6 @@
 TARGET = ./cc-backend
 FRONTEND = ./web/frontend
-VERSION = 1.5.2
+VERSION = 1.5.3
 GIT_HASH := $(shell git rev-parse --short HEAD || echo 'development')
 CURRENT_TIME = $(shell date +"%Y-%m-%d:T%H:%M:%S")
 LD_FLAGS = '-s -X main.date=${CURRENT_TIME} -X main.version=${VERSION} -X main.commit=${GIT_HASH}'

ReleaseNotes.md

@@ -1,4 +1,4 @@
-# `cc-backend` version 1.5.2
+# `cc-backend` version 1.5.3
 
 Supports job archive version 3 and database version 11.
 
@@ -15,6 +15,47 @@ While we are confident that the memory issue with the metricstore cleanup move
 policy is fixed, it is still recommended to use delete policy for cleanup.
 This is also the default.
 
+## Changes in 1.5.3
+
+### Bug fixes
+
+- **Doubleranged filter fixes**: Range filters now correctly handle zero as a
+  boundary value. Improved validation and UI text for "more than equal" and
+  "less than equal" range selections.
+- **Lineprotocol body parsing interrupted**: Switched from `ReadTimeout` to
+  `ReadHeaderTimeout` so that long-running metric submissions are no longer
+  cut off mid-stream.
+- **Checkpoint archiving continues on error**: A single cluster's archiving
+  failure no longer aborts the entire cleanup operation. Errors are collected
+  and reported per cluster.
+- **Parquet row group overflow**: Added periodic flush during checkpoint
+  archiving to prevent exceeding the parquet-go 32k column-write limit.
+- **Removed metrics excluded from subcluster config**: Metrics removed from a
+  subcluster are no longer returned by `GetMetricConfigSubCluster`.
+
+### MetricStore performance
+
+- **WAL writer throughput**: Decoupled WAL file flushing from message processing
+  using a periodic 5-second batch flush (up to 4096 messages per cycle),
+  significantly increasing metric ingestion throughput.
+- **Improved shutdown time**: HTTP shutdown timeout reduced; metricstore and
+  archiver now shut down concurrently. Overall shutdown deadline raised to
+  60 seconds.
+
+### New features
+
+- **Manual checkpoint cleanup flag**: New `-cleanup-checkpoints` CLI flag
+  triggers checkpoint cleanup without starting the server, useful for
+  maintenance windows or automated cleanup scripts.
+- **Explicit node state queries in node view**: Node health and scheduler state
+  are now fetched independently from metric data for fresher status information.
+
+### Logging improvements
+
+- **Reduced tagger log noise**: Missing metrics and expression evaluation errors
+  in the job classification tagger are now logged at debug level instead of
+  error level.
+
 ## Changes in 1.5.2
 
 ### Bug fixes

cmd/cc-backend/server.go

@@ -407,21 +407,27 @@ func (s *Server) Start(ctx context.Context) error {
 }
 
 func (s *Server) Shutdown(ctx context.Context) {
-	shutdownCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
-	defer cancel()
+	shutdownStart := time.Now()
 
+	natsStart := time.Now()
 	nc := nats.GetClient()
 	if nc != nil {
 		nc.Close()
 	}
+	cclog.Infof("Shutdown: NATS closed (%v)", time.Since(natsStart))
 
+	httpStart := time.Now()
+	shutdownCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+	defer cancel()
 	if err := s.server.Shutdown(shutdownCtx); err != nil {
 		cclog.Errorf("Server shutdown error: %v", err)
 	}
+	cclog.Infof("Shutdown: HTTP server stopped (%v)", time.Since(httpStart))
 
 	// Run metricstore and archiver shutdown concurrently.
 	// They are independent: metricstore writes .bin snapshots,
 	// archiver flushes pending job archives.
+	storeStart := time.Now()
 	done := make(chan struct{})
 	go func() {
 		defer close(done)
@@ -444,7 +450,10 @@ func (s *Server) Shutdown(ctx context.Context) {
 
 	select {
 	case <-done:
+		cclog.Infof("Shutdown: metricstore + archiver completed (%v)", time.Since(storeStart))
 	case <-time.After(60 * time.Second):
-		cclog.Warn("Shutdown deadline exceeded, forcing exit")
+		cclog.Warnf("Shutdown deadline exceeded after %v, forcing exit", time.Since(shutdownStart))
 	}
+
+	cclog.Infof("Shutdown: total time %v", time.Since(shutdownStart))
 }

pkg/metricstore/archive.go

@@ -53,6 +53,16 @@ func cleanUpWorker(wg *sync.WaitGroup, ctx context.Context, interval string, mod
 			return
 		}
 
+		// Account for checkpoint span: files named {from}.bin contain data up to
+		// from+checkpointInterval. Subtract the checkpoint interval so we don't
+		// delete files whose data still falls within the retention window.
+		checkpointSpan := 12 * time.Hour
+		if Keys.CheckpointInterval != "" {
+			if parsed, err := time.ParseDuration(Keys.CheckpointInterval); err == nil {
+				checkpointSpan = parsed
+			}
+		}
+
 		ticker := time.NewTicker(d)
 		defer ticker.Stop()
 
@@ -61,7 +71,7 @@ func cleanUpWorker(wg *sync.WaitGroup, ctx context.Context, interval string, mod
 			case <-ctx.Done():
 				return
 			case <-ticker.C:
-				t := time.Now().Add(-d)
+				t := time.Now().Add(-d).Add(-checkpointSpan)
 				cclog.Infof("[METRICSTORE]> start %s checkpoints (older than %s)...", mode, t.Format(time.RFC3339))
 
 				n, err := CleanupCheckpoints(Keys.Checkpoints.RootDir, cleanupDir, t.Unix(), delete)

pkg/metricstore/buffer.go

@@ -146,7 +146,9 @@ var (
 
 	// ErrDataDoesNotAlign indicates that aggregated data from child scopes
 	// does not align with the parent scope's expected timestamps/intervals.
-	ErrDataDoesNotAlign error = errors.New("[METRICSTORE]> data from lower granularities does not align")
+	ErrDataDoesNotAlignMissingFront    error = errors.New("[METRICSTORE]> data from lower granularities does not align (missing data prior to start of the buffers)")
+	ErrDataDoesNotAlignMissingBack     error = errors.New("[METRICSTORE]> data from lower granularities does not align (missing data after the end of the buffers)")
+	ErrDataDoesNotAlignDataLenMismatch error = errors.New("[METRICSTORE]> data from lower granularities does not align (collected data length is different than expected data length)")
 )
 
 // buffer stores time-series data for a single metric at a specific hierarchical level.

pkg/metricstore/checkpoint.go

@@ -86,14 +86,16 @@ var (
 
 // Checkpointing starts a background worker that periodically saves metric data to disk.
 //
-// Checkpoints are written every 12 hours (hardcoded).
+// restoreFrom is the earliest timestamp of data loaded from checkpoint files at startup.
+// The first periodic checkpoint after restart will cover [restoreFrom, now], ensuring that
+// loaded data is re-persisted before old checkpoint files are cleaned up.
 //
 // Format behaviour:
 //   - "json": Periodic checkpointing every checkpointInterval
 //   - "wal":  Periodic binary snapshots + WAL rotation every checkpointInterval
-func Checkpointing(wg *sync.WaitGroup, ctx context.Context) {
+func Checkpointing(wg *sync.WaitGroup, ctx context.Context, restoreFrom time.Time) {
 	lastCheckpointMu.Lock()
-	lastCheckpoint = time.Now()
+	lastCheckpoint = restoreFrom
 	lastCheckpointMu.Unlock()
 
 	ms := GetMemoryStore()
@@ -337,25 +339,35 @@ func (l *Level) toCheckpoint(dir string, from, to int64, m *MemoryStore) error {
 		return ErrNoNewArchiveData
 	}
 
-	filepath := path.Join(dir, fmt.Sprintf("%d.json", from))
-	f, err := os.OpenFile(filepath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)
+	finalPath := path.Join(dir, fmt.Sprintf("%d.json", from))
+	tmpPath := finalPath + ".tmp"
+
+	f, err := os.OpenFile(tmpPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)
 	if err != nil && os.IsNotExist(err) {
 		err = os.MkdirAll(dir, CheckpointDirPerms)
 		if err == nil {
-			f, err = os.OpenFile(filepath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)
+			f, err = os.OpenFile(tmpPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, CheckpointFilePerms)
 		}
 	}
 	if err != nil {
 		return err
 	}
-	defer f.Close()
 
 	bw := bufio.NewWriter(f)
 	if err = json.NewEncoder(bw).Encode(cf); err != nil {
+		f.Close()
+		os.Remove(tmpPath)
 		return err
 	}
 
-	return bw.Flush()
+	if err = bw.Flush(); err != nil {
+		f.Close()
+		os.Remove(tmpPath)
+		return err
+	}
+	f.Close()
+
+	return os.Rename(tmpPath, finalPath)
 }
 
 // enqueueCheckpointHosts traverses checkpoint directory and enqueues cluster/host pairs.
@@ -470,7 +482,7 @@ func (l *Level) loadFile(cf *CheckpointFile, m *MemoryStore) error {
 			data:      metric.Data[0:n:n],
 			prev:      nil,
 			next:      nil,
-			archived:  true,
+			archived:  false,
 		}
 
 		minfo, ok := m.Metrics[name]

pkg/metricstore/metricstore.go

@@ -170,7 +170,7 @@ func Init(rawConfig json.RawMessage, metrics map[string]MetricConfig, wg *sync.W
 	ctx, shutdown := context.WithCancel(context.Background())
 
 	Retention(wg, ctx)
-	Checkpointing(wg, ctx)
+	Checkpointing(wg, ctx, restoreFrom)
 	CleanUp(wg, ctx)
 	WALStaging(wg, ctx)
 	MemoryUsageTracker(wg, ctx)
@@ -271,19 +271,32 @@ func (ms *MemoryStore) SetNodeProvider(provider NodeProvider) {
 //
 // Note: This function blocks until the final checkpoint is written.
 func Shutdown() {
+	totalStart := time.Now()
+
 	shutdownFuncMu.Lock()
 	defer shutdownFuncMu.Unlock()
 	if shutdownFunc != nil {
 		shutdownFunc()
 	}
+	cclog.Infof("[METRICSTORE]> Background workers cancelled (%v)", time.Since(totalStart))
 
 	if Keys.Checkpoints.FileFormat == "wal" {
+		// Signal producers to stop sending before closing channels,
+		// preventing send-on-closed-channel panics from in-flight NATS workers.
+		walShuttingDown.Store(true)
+		// Brief grace period for in-flight DecodeLine calls to complete.
+		time.Sleep(100 * time.Millisecond)
+
 		for _, ch := range walShardChs {
 			close(ch)
 		}
+		drainStart := time.Now()
+		WaitForWALStagingDrain()
+		cclog.Infof("[METRICSTORE]> WAL staging goroutines exited (%v)", time.Since(drainStart))
 	}
 
-	cclog.Infof("[METRICSTORE]> Writing to '%s'...\n", Keys.Checkpoints.RootDir)
+	cclog.Infof("[METRICSTORE]> Writing checkpoint to '%s'...", Keys.Checkpoints.RootDir)
+	checkpointStart := time.Now()
 	var files int
 	var err error
 
@@ -294,19 +307,16 @@ func Shutdown() {
 	lastCheckpointMu.Unlock()
 
 	if Keys.Checkpoints.FileFormat == "wal" {
-		var hostDirs []string
-		files, hostDirs, err = ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), time.Now().Unix())
-		if err == nil {
-			RotateWALFilesAfterShutdown(hostDirs)
-		}
+		// WAL files are deleted per-host inside ToCheckpointWAL workers.
+		files, _, err = ms.ToCheckpointWAL(Keys.Checkpoints.RootDir, from.Unix(), time.Now().Unix())
 	} else {
 		files, err = ms.ToCheckpoint(Keys.Checkpoints.RootDir, from.Unix(), time.Now().Unix())
 	}
 
 	if err != nil {
-		cclog.Errorf("[METRICSTORE]> Writing checkpoint failed: %s\n", err.Error())
+		cclog.Errorf("[METRICSTORE]> Writing checkpoint failed: %s", err.Error())
 	}
-	cclog.Infof("[METRICSTORE]> Done! (%d files written)\n", files)
+	cclog.Infof("[METRICSTORE]> Done! (%d files written in %v, total shutdown: %v)", files, time.Since(checkpointStart), time.Since(totalStart))
 }
 
 // Retention starts a background goroutine that periodically frees old metric data.
@@ -702,16 +712,16 @@ func (m *MemoryStore) Read(selector util.Selector, metric string, from, to, reso
 		} else if from != cfrom || to != cto || len(data) != len(cdata) {
 			missingfront, missingback := int((from-cfrom)/minfo.Frequency), int((to-cto)/minfo.Frequency)
 			if missingfront != 0 {
-				return ErrDataDoesNotAlign
+				return ErrDataDoesNotAlignMissingFront
 			}
 
 			newlen := len(cdata) - missingback
 			if newlen < 1 {
-				return ErrDataDoesNotAlign
+				return ErrDataDoesNotAlignMissingBack
 			}
 			cdata = cdata[0:newlen]
 			if len(cdata) != len(data) {
-				return ErrDataDoesNotAlign
+				return ErrDataDoesNotAlignDataLenMismatch
 			}
 
 			from, to = cfrom, cto

pkg/metricstore/stats.go

@@ -91,8 +91,10 @@ func (m *MemoryStore) Stats(selector util.Selector, metric string, from, to int6
 
 		if n == 0 {
 			from, to = cfrom, cto
-		} else if from != cfrom || to != cto {
-			return ErrDataDoesNotAlign
+		} else if from != cfrom {
+			return ErrDataDoesNotAlignMissingFront
+		} else if to != cto {
+			return ErrDataDoesNotAlignMissingBack
 		}
 
 		samples += stats.Samples

pkg/metricstore/walCheckpoint.go

@@ -92,6 +92,13 @@ var walShardRotateChs []chan walRotateReq
 // walNumShards stores the number of shards (set during WALStaging init).
 var walNumShards int
 
+// walStagingWg tracks WALStaging goroutine exits for shutdown synchronization.
+var walStagingWg sync.WaitGroup
+
+// walShuttingDown is set before closing shard channels to prevent
+// SendWALMessage from sending on a closed channel (which panics in Go).
+var walShuttingDown atomic.Bool
+
 // WALMessage represents a single metric write to be appended to the WAL.
 // Cluster and Node are NOT stored in the WAL record (inferred from file path).
 type WALMessage struct {
@@ -133,9 +140,9 @@ func walShardIndex(cluster, node string) int {
 }
 
 // SendWALMessage routes a WAL message to the appropriate shard channel.
-// Returns false if the channel is full (message dropped).
+// Returns false if the channel is full or shutdown is in progress.
 func SendWALMessage(msg *WALMessage) bool {
-	if walShardChs == nil {
+	if walShardChs == nil || walShuttingDown.Load() {
 		return false
 	}
 	shard := walShardIndex(msg.Cluster, msg.Node)
@@ -171,7 +178,9 @@ func WALStaging(wg *sync.WaitGroup, ctx context.Context) {
 		msgCh := walShardChs[i]
 		rotateCh := walShardRotateChs[i]
 
+		walStagingWg.Add(1)
 		wg.Go(func() {
+			defer walStagingWg.Done()
 			hostFiles := make(map[string]*walFileState)
 
 			defer func() {
@@ -255,23 +264,6 @@ func WALStaging(wg *sync.WaitGroup, ctx context.Context) {
 				}
 			}
 
-			drain := func() {
-				for {
-					select {
-					case msg, ok := <-msgCh:
-						if !ok {
-							return
-						}
-						processMsg(msg)
-					case req := <-rotateCh:
-						processRotate(req)
-					default:
-						flushDirty()
-						return
-					}
-				}
-			}
-
 			ticker := time.NewTicker(walFlushInterval)
 			defer ticker.Stop()
 
@@ -298,7 +290,10 @@ func WALStaging(wg *sync.WaitGroup, ctx context.Context) {
 			for {
 				select {
 				case <-ctx.Done():
-					drain()
+					// On shutdown, skip draining buffered messages — a full binary
+					// checkpoint will be written from in-memory state, making
+					// buffered WAL records redundant.
+					flushDirty()
 					return
 				case msg, ok := <-msgCh:
 					if !ok {
@@ -319,23 +314,42 @@ func WALStaging(wg *sync.WaitGroup, ctx context.Context) {
 	}
 }
 
+// WaitForWALStagingDrain blocks until all WALStaging goroutines have exited.
+// Must be called after closing walShardChs to ensure all file handles are
+// flushed and closed before checkpoint writes begin.
+func WaitForWALStagingDrain() {
+	walStagingWg.Wait()
+}
+
 // RotateWALFiles sends rotation requests for the given host directories
 // and blocks until all rotations complete. Each request is routed to the
 // shard that owns the host directory.
+//
+// If shutdown is in progress (WAL staging goroutines may have exited),
+// rotation is skipped to avoid deadlocking on abandoned channels.
 func RotateWALFiles(hostDirs []string) {
-	if walShardRotateChs == nil {
+	if walShardRotateChs == nil || walShuttingDown.Load() {
 		return
 	}
-	dones := make([]chan struct{}, len(hostDirs))
-	for i, dir := range hostDirs {
-		dones[i] = make(chan struct{})
-		// Extract cluster/node from hostDir to find the right shard.
-		// hostDir = rootDir/cluster/node
+	dones := make([]chan struct{}, 0, len(hostDirs))
+	for _, dir := range hostDirs {
+		done := make(chan struct{})
 		shard := walShardIndexFromDir(dir)
-		walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: dones[i]}
+		select {
+		case walShardRotateChs[shard] <- walRotateReq{hostDir: dir, done: done}:
+			dones = append(dones, done)
+		default:
+			// Channel full or goroutine not consuming — skip this host.
+			cclog.Warnf("[METRICSTORE]> WAL rotation skipped for %s (channel full)", dir)
+		}
 	}
 	for _, done := range dones {
-		<-done
+		select {
+		case <-done:
+		case <-time.After(30 * time.Second):
+			cclog.Warn("[METRICSTORE]> WAL rotation timed out, continuing")
+			return
+		}
 	}
 }
 
@@ -359,78 +373,64 @@ func RotateWALFilesAfterShutdown(hostDirs []string) {
 	}
 }
 
-// writeWALRecordDirect encodes a WAL record directly into the bufio.Writer,
-// avoiding heap allocations by using a stack-allocated scratch buffer for
-// the fixed-size header/trailer and computing CRC inline.
+// writeWALRecordDirect encodes a WAL record into a contiguous buffer first,
+// then writes it to the bufio.Writer in a single call. This prevents partial
+// records in the write buffer if a write error occurs mid-record (e.g. disk full).
 func writeWALRecordDirect(w *bufio.Writer, msg *WALMessage) error {
-	// Compute payload size.
+	// Compute payload and total record size.
 	payloadSize := 8 + 2 + len(msg.MetricName) + 1 + 4
 	for _, s := range msg.Selector {
 		payloadSize += 1 + len(s)
 	}
+	// Total: 8 (header) + payload + 4 (CRC).
+	totalSize := 8 + payloadSize + 4
 
-	// Write magic + payload length (8 bytes header).
-	var hdr [8]byte
-	binary.LittleEndian.PutUint32(hdr[0:4], walRecordMagic)
-	binary.LittleEndian.PutUint32(hdr[4:8], uint32(payloadSize))
-	if _, err := w.Write(hdr[:]); err != nil {
-		return err
+	// Use stack buffer for typical small records, heap-allocate only for large ones.
+	var stackBuf [256]byte
+	var buf []byte
+	if totalSize <= len(stackBuf) {
+		buf = stackBuf[:totalSize]
+	} else {
+		buf = make([]byte, totalSize)
 	}
 
-	// We need to compute CRC over the payload as we write it.
-	crc := crc32.NewIEEE()
+	// Header: magic + payload length.
+	binary.LittleEndian.PutUint32(buf[0:4], walRecordMagic)
+	binary.LittleEndian.PutUint32(buf[4:8], uint32(payloadSize))
+
+	// Payload starts at offset 8.
+	p := 8
 
 	// Timestamp (8 bytes).
-	var scratch [8]byte
-	binary.LittleEndian.PutUint64(scratch[:8], uint64(msg.Timestamp))
-	crc.Write(scratch[:8])
-	if _, err := w.Write(scratch[:8]); err != nil {
-		return err
-	}
+	binary.LittleEndian.PutUint64(buf[p:p+8], uint64(msg.Timestamp))
+	p += 8
 
 	// Metric name length (2 bytes) + metric name.
-	binary.LittleEndian.PutUint16(scratch[:2], uint16(len(msg.MetricName)))
-	crc.Write(scratch[:2])
-	if _, err := w.Write(scratch[:2]); err != nil {
-		return err
-	}
-	nameBytes := []byte(msg.MetricName)
-	crc.Write(nameBytes)
-	if _, err := w.Write(nameBytes); err != nil {
-		return err
-	}
+	binary.LittleEndian.PutUint16(buf[p:p+2], uint16(len(msg.MetricName)))
+	p += 2
+	p += copy(buf[p:], msg.MetricName)
 
 	// Selector count (1 byte).
-	scratch[0] = byte(len(msg.Selector))
-	crc.Write(scratch[:1])
-	if _, err := w.Write(scratch[:1]); err != nil {
-		return err
-	}
+	buf[p] = byte(len(msg.Selector))
+	p++
 
 	// Selectors (1-byte length + bytes each).
 	for _, sel := range msg.Selector {
-		scratch[0] = byte(len(sel))
-		crc.Write(scratch[:1])
-		if _, err := w.Write(scratch[:1]); err != nil {
-			return err
-		}
-		selBytes := []byte(sel)
-		crc.Write(selBytes)
-		if _, err := w.Write(selBytes); err != nil {
-			return err
-		}
+		buf[p] = byte(len(sel))
+		p++
+		p += copy(buf[p:], sel)
 	}
 
 	// Value (4 bytes, float32 bits).
-	binary.LittleEndian.PutUint32(scratch[:4], math.Float32bits(float32(msg.Value)))
-	crc.Write(scratch[:4])
-	if _, err := w.Write(scratch[:4]); err != nil {
-		return err
-	}
+	binary.LittleEndian.PutUint32(buf[p:p+4], math.Float32bits(float32(msg.Value)))
+	p += 4
 
-	// CRC32 (4 bytes).
-	binary.LittleEndian.PutUint32(scratch[:4], crc.Sum32())
-	_, err := w.Write(scratch[:4])
+	// CRC32 over payload (bytes 8..8+payloadSize).
+	crc := crc32.ChecksumIEEE(buf[8 : 8+payloadSize])
+	binary.LittleEndian.PutUint32(buf[p:p+4], crc)
+
+	// Single atomic write to the buffered writer.
+	_, err := w.Write(buf)
 	return err
 }
 
@@ -655,7 +655,10 @@ func (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string
 		selector []string
 	}
 
-	n, errs := int32(0), int32(0)
+	totalWork := len(levels)
+	cclog.Infof("[METRICSTORE]> Starting binary checkpoint for %d hosts with %d workers", totalWork, Keys.NumWorkers)
+
+	n, errs, completed := int32(0), int32(0), int32(0)
 	var successDirs []string
 	var successMu sync.Mutex
 
@@ -663,6 +666,22 @@ func (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string
 	wg.Add(Keys.NumWorkers)
 	work := make(chan workItem, Keys.NumWorkers*2)
 
+	// Progress logging goroutine.
+	stopProgress := make(chan struct{})
+	go func() {
+		ticker := time.NewTicker(10 * time.Second)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-ticker.C:
+				cclog.Infof("[METRICSTORE]> Checkpoint progress: %d/%d hosts (%d written, %d errors)",
+					atomic.LoadInt32(&completed), totalWork, atomic.LoadInt32(&n), atomic.LoadInt32(&errs))
+			case <-stopProgress:
+				return
+			}
+		}
+	}()
+
 	for range Keys.NumWorkers {
 		go func() {
 			defer wg.Done()
@@ -670,16 +689,23 @@ func (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string
 				err := wi.level.toCheckpointBinary(wi.hostDir, from, to, m)
 				if err != nil {
 					if err == ErrNoNewArchiveData {
+						atomic.AddInt32(&completed, 1)
 						continue
 					}
 					cclog.Errorf("[METRICSTORE]> binary checkpoint error for %s: %v", wi.hostDir, err)
 					atomic.AddInt32(&errs, 1)
 				} else {
 					atomic.AddInt32(&n, 1)
+					// Delete WAL immediately after successful snapshot.
+					walPath := path.Join(wi.hostDir, "current.wal")
+					if err := os.Remove(walPath); err != nil && !os.IsNotExist(err) {
+						cclog.Errorf("[METRICSTORE]> WAL remove %s: %v", walPath, err)
+					}
 					successMu.Lock()
 					successDirs = append(successDirs, wi.hostDir)
 					successMu.Unlock()
 				}
+				atomic.AddInt32(&completed, 1)
 			}
 		}()
 	}
@@ -694,6 +720,7 @@ func (m *MemoryStore) ToCheckpointWAL(dir string, from, to int64) (int, []string
 	}
 	close(work)
 	wg.Wait()
+	close(stopProgress)
 
 	if errs > 0 {
 		return int(n), successDirs, fmt.Errorf("[METRICSTORE]> %d errors during binary checkpoint (%d successes)", errs, n)

tools/binaryCheckpointReader/binaryCheckpointReader.go

@@ -0,0 +1,381 @@
+// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.
+// All rights reserved. This file is part of cc-backend.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+// binaryCheckpointReader reads .wal or .bin checkpoint files produced by the
+// metricstore WAL/snapshot system and dumps their contents to a human-readable
+// .txt file (same name as input, with .txt extension).
+//
+// Usage:
+//
+//	go run ./tools/binaryCheckpointReader <file.wal|file.bin>
+package main
+
+import (
+	"bufio"
+	"encoding/binary"
+	"fmt"
+	"hash/crc32"
+	"io"
+	"math"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+// Magic numbers matching metricstore/walCheckpoint.go.
+const (
+	walFileMagic   = uint32(0xCC1DA701)
+	walRecordMagic = uint32(0xCC1DA7A1)
+	snapFileMagic  = uint32(0xCC5B0001)
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Fprintf(os.Stderr, "Usage: %s <file.wal|file.bin>\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	inputPath := os.Args[1]
+	ext := strings.ToLower(filepath.Ext(inputPath))
+
+	if ext != ".wal" && ext != ".bin" {
+		fmt.Fprintf(os.Stderr, "Error: file must have .wal or .bin extension, got %q\n", ext)
+		os.Exit(1)
+	}
+
+	f, err := os.Open(inputPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error opening %s: %v\n", inputPath, err)
+		os.Exit(1)
+	}
+	defer f.Close()
+
+	// Output file: replace extension with .txt
+	outputPath := strings.TrimSuffix(inputPath, filepath.Ext(inputPath)) + ".txt"
+	out, err := os.Create(outputPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error creating output %s: %v\n", outputPath, err)
+		os.Exit(1)
+	}
+	defer out.Close()
+
+	w := bufio.NewWriter(out)
+	defer w.Flush()
+
+	switch ext {
+	case ".wal":
+		err = dumpWAL(f, w)
+	case ".bin":
+		err = dumpBinarySnapshot(f, w)
+	}
+
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error reading %s: %v\n", inputPath, err)
+		os.Exit(1)
+	}
+
+	w.Flush()
+	fmt.Printf("Output written to %s\n", outputPath)
+}
+
+// ---------- WAL reader ----------
+
+func dumpWAL(f *os.File, w *bufio.Writer) error {
+	br := bufio.NewReader(f)
+
+	// Read and verify file header magic.
+	var fileMagic uint32
+	if err := binary.Read(br, binary.LittleEndian, &fileMagic); err != nil {
+		if err == io.EOF {
+			fmt.Fprintln(w, "WAL file is empty (0 bytes).")
+			return nil
+		}
+		return fmt.Errorf("read file header: %w", err)
+	}
+
+	if fileMagic != walFileMagic {
+		return fmt.Errorf("invalid WAL file magic 0x%08X (expected 0x%08X)", fileMagic, walFileMagic)
+	}
+
+	fmt.Fprintf(w, "=== WAL File Dump ===\n")
+	fmt.Fprintf(w, "File:        %s\n", f.Name())
+	fmt.Fprintf(w, "File Magic:  0x%08X (valid)\n\n", fileMagic)
+
+	recordNum := 0
+	for {
+		msg, err := readWALRecord(br)
+		if err != nil {
+			fmt.Fprintf(w, "--- Record #%d: ERROR ---\n", recordNum+1)
+			fmt.Fprintf(w, "  Error: %v\n", err)
+			fmt.Fprintf(w, "  (stopping replay — likely truncated trailing record)\n\n")
+			break
+		}
+		if msg == nil {
+			break // Clean EOF
+		}
+
+		recordNum++
+		ts := time.Unix(msg.Timestamp, 0).UTC()
+
+		fmt.Fprintf(w, "--- Record #%d ---\n", recordNum)
+		fmt.Fprintf(w, "  Timestamp:   %d (%s)\n", msg.Timestamp, ts.Format(time.RFC3339))
+		fmt.Fprintf(w, "  Metric:      %s\n", msg.MetricName)
+		if len(msg.Selector) > 0 {
+			fmt.Fprintf(w, "  Selectors:   [%s]\n", strings.Join(msg.Selector, ", "))
+		} else {
+			fmt.Fprintf(w, "  Selectors:   (none)\n")
+		}
+		fmt.Fprintf(w, "  Value:       %g\n\n", msg.Value)
+	}
+
+	fmt.Fprintf(w, "=== Total valid records: %d ===\n", recordNum)
+	return nil
+}
+
+type walMessage struct {
+	MetricName string
+	Selector   []string
+	Value      float32
+	Timestamp  int64
+}
+
+func readWALRecord(r io.Reader) (*walMessage, error) {
+	var magic uint32
+	if err := binary.Read(r, binary.LittleEndian, &magic); err != nil {
+		if err == io.EOF {
+			return nil, nil
+		}
+		return nil, fmt.Errorf("read record magic: %w", err)
+	}
+
+	if magic != walRecordMagic {
+		return nil, fmt.Errorf("invalid record magic 0x%08X (expected 0x%08X)", magic, walRecordMagic)
+	}
+
+	var payloadLen uint32
+	if err := binary.Read(r, binary.LittleEndian, &payloadLen); err != nil {
+		return nil, fmt.Errorf("read payload length: %w", err)
+	}
+
+	if payloadLen > 1<<20 {
+		return nil, fmt.Errorf("record payload too large: %d bytes", payloadLen)
+	}
+
+	payload := make([]byte, payloadLen)
+	if _, err := io.ReadFull(r, payload); err != nil {
+		return nil, fmt.Errorf("read payload: %w", err)
+	}
+
+	var storedCRC uint32
+	if err := binary.Read(r, binary.LittleEndian, &storedCRC); err != nil {
+		return nil, fmt.Errorf("read CRC: %w", err)
+	}
+
+	if crc32.ChecksumIEEE(payload) != storedCRC {
+		return nil, fmt.Errorf("CRC mismatch (truncated write or corruption)")
+	}
+
+	return parseWALPayload(payload)
+}
+
+func parseWALPayload(payload []byte) (*walMessage, error) {
+	if len(payload) < 8+2+1+4 {
+		return nil, fmt.Errorf("payload too short: %d bytes", len(payload))
+	}
+
+	offset := 0
+
+	// Timestamp (8 bytes).
+	ts := int64(binary.LittleEndian.Uint64(payload[offset : offset+8]))
+	offset += 8
+
+	// Metric name (2-byte length + bytes).
+	if offset+2 > len(payload) {
+		return nil, fmt.Errorf("metric name length overflows payload")
+	}
+	mLen := int(binary.LittleEndian.Uint16(payload[offset : offset+2]))
+	offset += 2
+
+	if offset+mLen > len(payload) {
+		return nil, fmt.Errorf("metric name overflows payload")
+	}
+	metricName := string(payload[offset : offset+mLen])
+	offset += mLen
+
+	// Selector count (1 byte).
+	if offset >= len(payload) {
+		return nil, fmt.Errorf("selector count overflows payload")
+	}
+	selCount := int(payload[offset])
+	offset++
+
+	selectors := make([]string, selCount)
+	for i := range selCount {
+		if offset >= len(payload) {
+			return nil, fmt.Errorf("selector[%d] length overflows payload", i)
+		}
+		sLen := int(payload[offset])
+		offset++
+
+		if offset+sLen > len(payload) {
+			return nil, fmt.Errorf("selector[%d] data overflows payload", i)
+		}
+		selectors[i] = string(payload[offset : offset+sLen])
+		offset += sLen
+	}
+
+	// Value (4 bytes, float32 bits).
+	if offset+4 > len(payload) {
+		return nil, fmt.Errorf("value overflows payload")
+	}
+	bits := binary.LittleEndian.Uint32(payload[offset : offset+4])
+	value := math.Float32frombits(bits)
+
+	return &walMessage{
+		MetricName: metricName,
+		Timestamp:  ts,
+		Selector:   selectors,
+		Value:      value,
+	}, nil
+}
+
+// ---------- Binary snapshot reader ----------
+
+func dumpBinarySnapshot(f *os.File, w *bufio.Writer) error {
+	br := bufio.NewReader(f)
+
+	var magic uint32
+	if err := binary.Read(br, binary.LittleEndian, &magic); err != nil {
+		return fmt.Errorf("read magic: %w", err)
+	}
+	if magic != snapFileMagic {
+		return fmt.Errorf("invalid snapshot magic 0x%08X (expected 0x%08X)", magic, snapFileMagic)
+	}
+
+	var from, to int64
+	if err := binary.Read(br, binary.LittleEndian, &from); err != nil {
+		return fmt.Errorf("read from: %w", err)
+	}
+	if err := binary.Read(br, binary.LittleEndian, &to); err != nil {
+		return fmt.Errorf("read to: %w", err)
+	}
+
+	fromTime := time.Unix(from, 0).UTC()
+	toTime := time.Unix(to, 0).UTC()
+
+	fmt.Fprintf(w, "=== Binary Snapshot Dump ===\n")
+	fmt.Fprintf(w, "File:    %s\n", f.Name())
+	fmt.Fprintf(w, "Magic:   0x%08X (valid)\n", magic)
+	fmt.Fprintf(w, "From:    %d (%s)\n", from, fromTime.Format(time.RFC3339))
+	fmt.Fprintf(w, "To:      %d (%s)\n\n", to, toTime.Format(time.RFC3339))
+
+	return dumpBinaryLevel(br, w, 0)
+}
+
+func dumpBinaryLevel(r io.Reader, w *bufio.Writer, depth int) error {
+	indent := strings.Repeat("  ", depth)
+
+	var numMetrics uint32
+	if err := binary.Read(r, binary.LittleEndian, &numMetrics); err != nil {
+		return fmt.Errorf("read num_metrics: %w", err)
+	}
+
+	if numMetrics > 0 {
+		fmt.Fprintf(w, "%sMetrics (%d):\n", indent, numMetrics)
+	}
+
+	for i := range numMetrics {
+		name, err := readString16(r)
+		if err != nil {
+			return fmt.Errorf("read metric name [%d]: %w", i, err)
+		}
+
+		var freq, start int64
+		if err := binary.Read(r, binary.LittleEndian, &freq); err != nil {
+			return fmt.Errorf("read frequency for %s: %w", name, err)
+		}
+		if err := binary.Read(r, binary.LittleEndian, &start); err != nil {
+			return fmt.Errorf("read start for %s: %w", name, err)
+		}
+
+		var numValues uint32
+		if err := binary.Read(r, binary.LittleEndian, &numValues); err != nil {
+			return fmt.Errorf("read num_values for %s: %w", name, err)
+		}
+
+		startTime := time.Unix(start, 0).UTC()
+
+		fmt.Fprintf(w, "%s  [%s]\n", indent, name)
+		fmt.Fprintf(w, "%s    Frequency:  %d s\n", indent, freq)
+		fmt.Fprintf(w, "%s    Start:      %d (%s)\n", indent, start, startTime.Format(time.RFC3339))
+		fmt.Fprintf(w, "%s    Values (%d):", indent, numValues)
+
+		if numValues == 0 {
+			fmt.Fprintln(w, " (none)")
+		} else {
+			fmt.Fprintln(w)
+			// Print values in rows of 10 for readability.
+			for j := range numValues {
+				var bits uint32
+				if err := binary.Read(r, binary.LittleEndian, &bits); err != nil {
+					return fmt.Errorf("read value[%d] for %s: %w", j, name, err)
+				}
+				val := math.Float32frombits(bits)
+
+				if j%10 == 0 {
+					if j > 0 {
+						fmt.Fprintln(w)
+					}
+					// Print the timestamp for this row's first value.
+					rowTS := start + int64(j)*freq
+					fmt.Fprintf(w, "%s      [%s] ", indent, time.Unix(rowTS, 0).UTC().Format("15:04:05"))
+				}
+
+				if math.IsNaN(float64(val)) {
+					fmt.Fprintf(w, "NaN ")
+				} else {
+					fmt.Fprintf(w, "%g ", val)
+				}
+			}
+			fmt.Fprintln(w)
+		}
+	}
+
+	var numChildren uint32
+	if err := binary.Read(r, binary.LittleEndian, &numChildren); err != nil {
+		return fmt.Errorf("read num_children: %w", err)
+	}
+
+	if numChildren > 0 {
+		fmt.Fprintf(w, "%sChildren (%d):\n", indent, numChildren)
+	}
+
+	for i := range numChildren {
+		childName, err := readString16(r)
+		if err != nil {
+			return fmt.Errorf("read child name [%d]: %w", i, err)
+		}
+
+		fmt.Fprintf(w, "%s  [%s]\n", indent, childName)
+		if err := dumpBinaryLevel(r, w, depth+2); err != nil {
+			return fmt.Errorf("read child %s: %w", childName, err)
+		}
+	}
+
+	return nil
+}
+
+func readString16(r io.Reader) (string, error) {
+	var sLen uint16
+	if err := binary.Read(r, binary.LittleEndian, &sLen); err != nil {
+		return "", err
+	}
+	buf := make([]byte, sLen)
+	if _, err := io.ReadFull(r, buf); err != nil {
+		return "", err
+	}
+	return string(buf), nil
+}

web/frontend/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "cc-frontend",
-  "version": "1.5.2",
+  "version": "1.5.3",
   "lockfileVersion": 4,
   "requires": true,
   "packages": {
     "": {
       "name": "cc-frontend",
-      "version": "1.5.2",
+      "version": "1.5.3",
       "license": "MIT",
       "dependencies": {
         "@rollup/plugin-replace": "^6.0.3",
@@ -328,6 +328,9 @@
       "cpu": [
         "arm"
       ],
+      "libc": [
+        "glibc"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -341,6 +344,9 @@
       "cpu": [
         "arm"
       ],
+      "libc": [
+        "musl"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -354,6 +360,9 @@
       "cpu": [
         "arm64"
       ],
+      "libc": [
+        "glibc"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -367,6 +376,9 @@
       "cpu": [
         "arm64"
       ],
+      "libc": [
+        "musl"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -380,6 +392,9 @@
       "cpu": [
         "loong64"
       ],
+      "libc": [
+        "glibc"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -393,6 +408,9 @@
       "cpu": [
         "loong64"
       ],
+      "libc": [
+        "musl"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -406,6 +424,9 @@
       "cpu": [
         "ppc64"
       ],
+      "libc": [
+        "glibc"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -419,6 +440,9 @@
       "cpu": [
         "ppc64"
       ],
+      "libc": [
+        "musl"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -432,6 +456,9 @@
       "cpu": [
         "riscv64"
       ],
+      "libc": [
+        "glibc"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -445,6 +472,9 @@
       "cpu": [
         "riscv64"
       ],
+      "libc": [
+        "musl"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -458,6 +488,9 @@
       "cpu": [
         "s390x"
       ],
+      "libc": [
+        "glibc"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -471,6 +504,9 @@
       "cpu": [
         "x64"
       ],
+      "libc": [
+        "glibc"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -484,6 +520,9 @@
       "cpu": [
         "x64"
       ],
+      "libc": [
+        "musl"
+      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -959,9 +998,9 @@
       "license": "MIT"
     },
     "node_modules/picomatch": {
-      "version": "4.0.4",
-      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-4.0.4.tgz",
-      "integrity": "sha512-QP88BAKvMam/3NxH6vj2o21R6MjxZUAd6nlwAS/pnGvN9IVLocLHxGYIzFhg6fUQ+5th6P4dv4eW9jX3DSIj7A==",
+      "version": "4.0.3",
+      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-4.0.3.tgz",
+      "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
       "license": "MIT",
       "engines": {
         "node": ">=12"
@@ -1095,9 +1134,9 @@
       }
     },
     "node_modules/rollup-plugin-svelte/node_modules/picomatch": {
-      "version": "2.3.2",
-      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-2.3.2.tgz",
-      "integrity": "sha512-V7+vQEJ06Z+c5tSye8S+nHUfI51xoXIXjHQ99cQtKUkQqqO1kO/KCJUfZXuB47h/YBlDhah2H3hdUGXn8ie0oA==",
+      "version": "2.3.1",
+      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-2.3.1.tgz",
+      "integrity": "sha512-JU3teHTNjmE2VCGFzuY8EXzCDVwEqB2a8fsIvwaStHhAWJEeVd1o1QD80CU6+ZdEXXSLbSsuLwJjkCBWqRQUVA==",
       "dev": true,
       "license": "MIT",
       "engines": {

web/frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "cc-frontend",
-  "version": "1.5.2",
+  "version": "1.5.3",
   "license": "MIT",
   "scripts": {
     "build": "rollup -c",