fix: cap CPU and avoid heavy startup work

cmd/server/main.go

@@ -19,6 +19,7 @@ import (
 	"os"
 	"os/signal"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"syscall"
 	"time"
@@ -73,6 +74,8 @@ func main() {
 	}
 
 	repos := repository.New(db)
+	service.ApplyRuntimeSettings(context.Background(), cfg, repos, logger)
+	applyCPUThreadLimit(cfg, logger)
 	services := service.New(cfg, logger, repos)
 
 	if err := services.Auth.SeedAdmin(context.Background()); err != nil {
@@ -126,6 +129,18 @@ func main() {
 	logger.Info("MediaStationGo stopped")
 }
 
+func applyCPUThreadLimit(cfg *config.Config, logger *zap.Logger) {
+	if cfg == nil || cfg.App.MaxCPUThreads < 1 {
+		return
+	}
+	prev := runtime.GOMAXPROCS(cfg.App.MaxCPUThreads)
+	if logger != nil {
+		logger.Info("runtime CPU thread limit applied",
+			zap.Int("max_cpu_threads", cfg.App.MaxCPUThreads),
+			zap.Int("previous", prev))
+	}
+}
+
 func buildRouter(cfg *config.Config, logger *zap.Logger, svc *service.Container) *gin.Engine {
 	if !cfg.App.Debug {
 		gin.SetMode(gin.ReleaseMode)

config.example.yaml

@@ -20,6 +20,7 @@ app:
   web_dir: ./web/dist
   ffmpeg_path: ffmpeg
   ffprobe_path: ffprobe
+  max_cpu_threads: 2   # hard cap for Go CPU threads; raise only on powerful hosts
   vaapi_device: /dev/dri/renderD128
   cors_origins: []     # leave empty to allow * in dev; set strict allow-list in prod
   server_url: ""       # public URL of the server (used for DLNA / casting)

internal/config/config.go

@@ -80,6 +80,7 @@ type AppConfig struct {
 	// NAS devices can become unresponsive when a scan starts many probe
 	// processes at once, so the default is deliberately conservative.
 	FFprobeMaxConcurrent int      `mapstructure:"ffprobe_max_concurrent"`
+	MaxCPUThreads        int      `mapstructure:"max_cpu_threads"`
 	VAAPIDevice          string   `mapstructure:"vaapi_device"`
 	CORSOrigins          []string `mapstructure:"cors_origins"`
 	ServerURL            string   `mapstructure:"server_url"`
@@ -223,6 +224,7 @@ func setDefaults(v *viper.Viper) {
 	v.SetDefault("app.ffmpeg_path", "ffmpeg")
 	v.SetDefault("app.ffprobe_path", "ffprobe")
 	v.SetDefault("app.ffprobe_max_concurrent", 1)
+	v.SetDefault("app.max_cpu_threads", 2)
 	v.SetDefault("app.vaapi_device", "/dev/dri/renderD128")
 	v.SetDefault("app.cors_origins", []string{})
 	v.SetDefault("app.server_url", "")
@@ -308,6 +310,12 @@ func (c *Config) normalize() error {
 	if c.Database.DBPath == "" {
 		c.Database.DBPath = filepath.Join(c.App.DataDir, "mediastation.db")
 	}
+	if c.App.MaxCPUThreads < 1 {
+		c.App.MaxCPUThreads = 1
+	}
+	if c.App.MaxCPUThreads > 8 {
+		c.App.MaxCPUThreads = 8
+	}
 	if c.Database.MaxOpenConns <= 1 {
 		c.Database.MaxOpenConns = defaultDatabaseMaxOpenConns
 	}

internal/config/config_test.go

@@ -25,6 +25,9 @@ func TestLoadDefaults(t *testing.T) {
 	if cfg.App.Port != 8080 {
 		t.Fatalf("expected default port 8080, got %d", cfg.App.Port)
 	}
+	if cfg.App.MaxCPUThreads != 2 {
+		t.Fatalf("expected default MaxCPUThreads 2, got %d", cfg.App.MaxCPUThreads)
+	}
 	if cfg.Database.DBPath == "" {
 		t.Fatalf("expected non-empty DBPath")
 	}

internal/database/database.go

@@ -86,8 +86,6 @@ func AutoMigrate(db *gorm.DB) error {
 
 func ensurePerformanceIndexes(db *gorm.DB) error {
 	statements := []string{
-		`CREATE INDEX IF NOT EXISTS idx_media_created_active ON media(created_at DESC) WHERE deleted_at IS NULL`,
-		`CREATE INDEX IF NOT EXISTS idx_media_episode_created_active ON media(created_at DESC) WHERE deleted_at IS NULL AND (season_num > 0 OR episode_num > 0)`,
 		`CREATE INDEX IF NOT EXISTS idx_media_library_created_active ON media(library_id, created_at DESC) WHERE deleted_at IS NULL`,
 		`CREATE INDEX IF NOT EXISTS idx_media_library_episode_active ON media(library_id, season_num, episode_num, created_at DESC) WHERE deleted_at IS NULL`,
 		`CREATE INDEX IF NOT EXISTS idx_media_series_active ON media(series_id, season_num, episode_num) WHERE deleted_at IS NULL`,

internal/database/database_test.go

@@ -58,8 +58,6 @@ func TestEnsurePerformanceIndexesCreatesHotPathIndexes(t *testing.T) {
 		t.Fatal(err)
 	}
 	for _, name := range []string{
-		"idx_media_created_active",
-		"idx_media_episode_created_active",
 		"idx_media_library_created_active",
 		"idx_media_library_episode_active",
 		"idx_favorites_user_media_active",

internal/repository/repository.go

@@ -114,10 +114,14 @@ func (r *UserRepository) ReleaseDeletedUsername(ctx context.Context, username st
 // FindByUsername returns the user matching username, or (nil, nil) when absent.
 func (r *UserRepository) FindByUsername(ctx context.Context, username string) (*model.User, error) {
 	var u model.User
+	err := withSQLiteBusyRetry(ctx, func() error {
+		u = model.User{}
 		err := r.db.WithContext(ctx).Where("username = ?", username).First(&u).Error
 		if errors.Is(err, gorm.ErrRecordNotFound) && username != "" {
 			err = r.db.WithContext(ctx).Where("LOWER(username) = LOWER(?)", username).First(&u).Error
 		}
+		return err
+	})
 	if errors.Is(err, gorm.ErrRecordNotFound) {
 		return nil, nil
 	}
@@ -130,7 +134,10 @@ func (r *UserRepository) FindByUsername(ctx context.Context, username string) (*
 // FindByID returns the user with the matching primary key, or (nil, nil).
 func (r *UserRepository) FindByID(ctx context.Context, id string) (*model.User, error) {
 	var u model.User
-	err := r.db.WithContext(ctx).Where("id = ?", id).First(&u).Error
+	err := withSQLiteBusyRetry(ctx, func() error {
+		u = model.User{}
+		return r.db.WithContext(ctx).Where("id = ?", id).First(&u).Error
+	})
 	if errors.Is(err, gorm.ErrRecordNotFound) {
 		return nil, nil
 	}
@@ -190,8 +197,10 @@ func (r *UserRepository) UpdatePassword(ctx context.Context, id, hash string) er
 // TouchLogin updates the last login timestamp.
 func (r *UserRepository) TouchLogin(ctx context.Context, id string) error {
 	now := time.Now()
+	return withSQLiteBusyRetry(ctx, func() error {
 		return r.db.WithContext(ctx).Model(&model.User{}).Where("id = ?", id).
 			Update("last_login_at", &now).Error
+	})
 }
 
 // Delete removes a user (soft-delete via gorm.DeletedAt), releases the unique
@@ -896,13 +905,18 @@ type RefreshTokenRepository struct{ db *gorm.DB }
 
 // Create inserts a new refresh token record.
 func (r *RefreshTokenRepository) Create(ctx context.Context, t *model.RefreshToken) error {
+	return withSQLiteBusyRetry(ctx, func() error {
 		return r.db.WithContext(ctx).Create(t).Error
+	})
 }
 
 // FindByHash returns the refresh token matching the hash, or (nil, nil).
 func (r *RefreshTokenRepository) FindByHash(ctx context.Context, hash string) (*model.RefreshToken, error) {
 	var t model.RefreshToken
-	err := r.db.WithContext(ctx).Where("token_hash = ?", hash).First(&t).Error
+	err := withSQLiteBusyRetry(ctx, func() error {
+		t = model.RefreshToken{}
+		return r.db.WithContext(ctx).Where("token_hash = ?", hash).First(&t).Error
+	})
 	if errors.Is(err, gorm.ErrRecordNotFound) {
 		return nil, nil
 	}
@@ -914,8 +928,10 @@ func (r *RefreshTokenRepository) FindByHash(ctx context.Context, hash string) (*
 
 // RevokeByUserID revokes all refresh tokens for a user.
 func (r *RefreshTokenRepository) RevokeByUserID(ctx context.Context, userID string) error {
+	return withSQLiteBusyRetry(ctx, func() error {
 		return r.db.WithContext(ctx).Model(&model.RefreshToken{}).
 			Where("user_id = ?", userID).Update("revoked", true).Error
+	})
 }
 
 // RevokeOldestActiveByUserID keeps at most limit active refresh tokens for a
@@ -924,6 +940,7 @@ func (r *RefreshTokenRepository) RevokeOldestActiveByUserID(ctx context.Context,
 	if limit < 1 {
 		limit = 1
 	}
+	return withSQLiteBusyRetry(ctx, func() error {
 		var tokens []model.RefreshToken
 		if err := r.db.WithContext(ctx).
 			Where("user_id = ? AND revoked = ? AND expires_at > ?", userID, false, time.Now()).
@@ -940,17 +957,22 @@ func (r *RefreshTokenRepository) RevokeOldestActiveByUserID(ctx context.Context,
 		}
 		return r.db.WithContext(ctx).Model(&model.RefreshToken{}).
 			Where("id IN ?", ids).Update("revoked", true).Error
+	})
 }
 
 // DeleteExpired removes all expired refresh tokens.
 func (r *RefreshTokenRepository) DeleteExpired(ctx context.Context) error {
+	return withSQLiteBusyRetry(ctx, func() error {
 		return r.db.WithContext(ctx).Where("expires_at < ?", time.Now()).Delete(&model.RefreshToken{}).Error
+	})
 }
 
 // Revoke revokes a specific refresh token.
 func (r *RefreshTokenRepository) Revoke(ctx context.Context, hash string) error {
+	return withSQLiteBusyRetry(ctx, func() error {
 		return r.db.WithContext(ctx).Model(&model.RefreshToken{}).
 			Where("token_hash = ?", hash).Update("revoked", true).Error
+	})
 }
 
 // HashToken returns the SHA256 hash of a token.

internal/repository/sqlite_busy_retry.go

@@ -0,0 +1,47 @@
+package repository
+
+import (
+	"context"
+	"strings"
+	"time"
+)
+
+const sqliteBusyRetryMaxElapsed = 6 * time.Second
+
+func withSQLiteBusyRetry(ctx context.Context, op func() error) error {
+	delay := 25 * time.Millisecond
+	deadline := time.Now().Add(sqliteBusyRetryMaxElapsed)
+	for {
+		err := op()
+		if !isSQLiteBusyError(err) {
+			return err
+		}
+		if ctxErr := ctx.Err(); ctxErr != nil {
+			return ctxErr
+		}
+		if time.Now().Add(delay).After(deadline) {
+			return err
+		}
+		timer := time.NewTimer(delay)
+		select {
+		case <-ctx.Done():
+			timer.Stop()
+			return ctx.Err()
+		case <-timer.C:
+		}
+		if delay < 500*time.Millisecond {
+			delay *= 2
+		}
+	}
+}
+
+func isSQLiteBusyError(err error) bool {
+	if err == nil {
+		return false
+	}
+	msg := strings.ToLower(err.Error())
+	return strings.Contains(msg, "sqlite_busy") ||
+		strings.Contains(msg, "sqlite_locked") ||
+		strings.Contains(msg, "database is locked") ||
+		strings.Contains(msg, "database table is locked")
+}

internal/service/auth_user_limits_test.go

@@ -5,15 +5,18 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"path/filepath"
 	"testing"
 	"time"
 
 	"github.com/glebarez/sqlite"
 	"github.com/golang-jwt/jwt/v5"
 	"go.uber.org/zap"
+	"golang.org/x/crypto/bcrypt"
 	"gorm.io/gorm"
 
 	"github.com/ShukeBta/MediaStationGo/internal/config"
+	"github.com/ShukeBta/MediaStationGo/internal/database"
 	"github.com/ShukeBta/MediaStationGo/internal/model"
 	"github.com/ShukeBta/MediaStationGo/internal/repository"
 )
@@ -227,6 +230,67 @@ func TestLoginKeepsOnlyConfiguredActiveRefreshTokens(t *testing.T) {
 	}
 }
 
+func TestLoginRetriesTransientSQLiteBusy(t *testing.T) {
+	ctx := context.Background()
+	cfg := &config.Config{}
+	cfg.App.DataDir = t.TempDir()
+	cfg.Database.DBPath = filepath.Join(cfg.App.DataDir, "busy-login.db")
+	cfg.Database.WALMode = true
+	cfg.Database.BusyTimeout = 20
+	cfg.Database.MaxOpenConns = 4
+	cfg.Database.MaxIdleConns = 2
+	cfg.Secrets.JWTSecret = "test-secret"
+	log := zap.NewNop()
+	db, err := database.Open(cfg, log)
+	if err != nil {
+		t.Fatal(err)
+	}
+	sqlDB, err := db.DB()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = sqlDB.Close() }()
+	if err := database.AutoMigrate(db); err != nil {
+		t.Fatal(err)
+	}
+	repos := repository.New(db)
+	permissions := NewPermissionService(log, repos)
+	auth := NewAuthService(cfg, log, repos, NewTokenService(cfg, log, repos), permissions)
+	hash, err := bcrypt.GenerateFromPassword([]byte("password"), bcrypt.MinCost)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := repos.User.Create(ctx, &model.User{
+		Username:     "viewer",
+		PasswordHash: string(hash),
+		Role:         "user",
+		Tier:         "free",
+		IsActive:     true,
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	tx := repos.DB.Begin()
+	if err := tx.Exec("UPDATE users SET updated_at = updated_at WHERE username = ?", "viewer").Error; err != nil {
+		t.Fatal(err)
+	}
+	release := make(chan struct{})
+	go func() {
+		timer := time.NewTimer(250 * time.Millisecond)
+		defer timer.Stop()
+		select {
+		case <-release:
+		case <-timer.C:
+		}
+		_ = tx.Rollback().Error
+	}()
+	defer close(release)
+
+	if _, err := auth.Login(ctx, "viewer", "password"); err != nil {
+		t.Fatalf("login should survive a transient sqlite write lock: %v", err)
+	}
+}
+
 func TestDefaultPermissionsAreViewerOnly(t *testing.T) {
 	perms := DefaultPermissions("user-1")
 	if !perms.CanViewDashboard || !perms.CanPlayMedia || !perms.CanExternalPlayer {

internal/service/downloads.go

@@ -1049,7 +1049,6 @@ func (d *DownloadService) completedTorrentSource(torrent QBitTorrent) string {
 	for _, candidate := range []string{
 		torrent.ContentPath,
 		filepath.Join(torrent.SavePath, torrent.Name),
-		torrent.SavePath,
 	} {
 		clean := strings.TrimSpace(candidate)
 		if clean == "" || clean == "." {

internal/service/downloads_test.go

@@ -87,6 +87,26 @@ func TestDownloadCompleteAutoOrganizesContentPath(t *testing.T) {
 	}
 }
 
+func TestCompletedTorrentSourceDoesNotFallbackToSavePath(t *testing.T) {
+	root := t.TempDir()
+	savePath := filepath.Join(root, "downloads", "日番")
+	if err := os.MkdirAll(savePath, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	svc := NewDownloadService(zap.NewNop(), newOrganizerTestRepo(t), NewHub(zap.NewNop()), nil)
+
+	got := svc.completedTorrentSource(QBitTorrent{
+		Hash:        "done123",
+		Name:        "Missing.Payload.S01",
+		SavePath:    savePath,
+		ContentPath: filepath.Join(savePath, "Missing.Payload.S01", "Missing.Payload.S01E01.mkv"),
+	})
+
+	if got != "" {
+		t.Fatalf("completedTorrentSource fell back to whole save_path %q; want empty", got)
+	}
+}
+
 func TestDownloadPollBaselinesAlreadyCompletedTorrents(t *testing.T) {
 	repos := newOrganizerTestRepo(t)
 	svc := NewDownloadService(zap.NewNop(), repos, NewHub(zap.NewNop()), nil)

internal/service/runtime_settings.go

@@ -49,6 +49,16 @@ func ApplyRuntimeSetting(cfg *config.Config, key, value string) {
 			}
 			cfg.App.FFprobeMaxConcurrent = n
 		}
+	case "app.max_cpu_threads", "runtime.max_cpu_threads":
+		if n, err := strconv.Atoi(value); err == nil {
+			if n < 1 {
+				n = 1
+			}
+			if n > 8 {
+				n = 8
+			}
+			cfg.App.MaxCPUThreads = n
+		}
 	case "transcode.enabled", "transcoder.enabled":
 		cfg.Transcoder.Enabled = parseBoolSetting(value, true)
 	case "transcode.hw_enabled", "transcoder.hardware_accel":

internal/service/runtime_settings_test.go

@@ -30,4 +30,14 @@ func TestApplyRuntimeSettingTranscodeSwitches(t *testing.T) {
 	if cfg.Transcoder.MaxConcurrent != 1 {
 		t.Fatalf("max concurrent = %d, want 1", cfg.Transcoder.MaxConcurrent)
 	}
+
+	ApplyRuntimeSetting(cfg, "app.max_cpu_threads", "99")
+	if cfg.App.MaxCPUThreads != 8 {
+		t.Fatalf("max cpu threads = %d, want clamp 8", cfg.App.MaxCPUThreads)
+	}
+
+	ApplyRuntimeSetting(cfg, "app.max_cpu_threads", "0")
+	if cfg.App.MaxCPUThreads != 1 {
+		t.Fatalf("max cpu threads = %d, want clamp 1", cfg.App.MaxCPUThreads)
+	}
 }