feat(loader): enhance single active backend by treating as singleton

core/application/application.go

@@ -16,7 +16,7 @@ type Application struct {
 func newApplication(appConfig *config.ApplicationConfig) *Application {
 	return &Application{
 		backendLoader:      config.NewBackendConfigLoader(appConfig.ModelPath),
-		modelLoader:        model.NewModelLoader(appConfig.ModelPath),
+		modelLoader:        model.NewModelLoader(appConfig.ModelPath, appConfig.SingleBackend),
 		applicationConfig:  appConfig,
 		templatesEvaluator: templates.NewEvaluator(appConfig.ModelPath),
 	}

core/application/startup.go

@@ -143,7 +143,7 @@ func New(opts ...config.AppOption) (*Application, error) {
 		}()
 	}
 
-	if options.LoadToMemory != nil {
+	if options.LoadToMemory != nil && !options.SingleBackend {
 		for _, m := range options.LoadToMemory {
 			cfg, err := application.BackendLoader().LoadBackendConfigFileByNameDefaultOptions(m, options)
 			if err != nil {

core/backend/embeddings.go

@@ -17,6 +17,7 @@ func ModelEmbedding(s string, tokens []int, loader *model.ModelLoader, backendCo
 	if err != nil {
 		return nil, err
 	}
+	defer loader.Close()
 
 	var fn func() ([]float32, error)
 	switch model := inferenceModel.(type) {

core/backend/image.go

@@ -16,6 +16,7 @@ func ImageGeneration(height, width, mode, step, seed int, positive_prompt, negat
 	if err != nil {
 		return nil, err
 	}
+	defer loader.Close()
 
 	fn := func() error {
 		_, err := inferenceModel.GenerateImage(

core/backend/llm.go

@@ -53,6 +53,7 @@ func ModelInference(ctx context.Context, s string, messages []schema.Message, im
 	if err != nil {
 		return nil, err
 	}
+	defer loader.Close()
 
 	var protoMessages []*proto.Message
 	// if we are using the tokenizer template, we need to convert the messages to proto messages

core/backend/options.go

@@ -40,10 +40,6 @@ func ModelOptions(c config.BackendConfig, so *config.ApplicationConfig, opts ...
 	grpcOpts := grpcModelOpts(c)
 	defOpts = append(defOpts, model.WithLoadGRPCLoadModelOpts(grpcOpts))
 
-	if so.SingleBackend {
-		defOpts = append(defOpts, model.WithSingleActiveBackend())
-	}
-
 	if so.ParallelBackendRequests {
 		defOpts = append(defOpts, model.EnableParallelRequests)
 	}
@@ -121,7 +117,7 @@ func grpcModelOpts(c config.BackendConfig) *pb.ModelOptions {
 	triggers := make([]*pb.GrammarTrigger, 0)
 	for _, t := range c.FunctionsConfig.GrammarConfig.GrammarTriggers {
 		triggers = append(triggers, &pb.GrammarTrigger{
-			Word:    t.Word,
+			Word: t.Word,
 		})
 
 	}
@@ -161,33 +157,33 @@ func grpcModelOpts(c config.BackendConfig) *pb.ModelOptions {
 		DisableLogStatus:     c.DisableLogStatus,
 		DType:                c.DType,
 		// LimitMMPerPrompt vLLM
-		LimitImagePerPrompt:  int32(c.LimitMMPerPrompt.LimitImagePerPrompt),
-		LimitVideoPerPrompt:  int32(c.LimitMMPerPrompt.LimitVideoPerPrompt),
-		LimitAudioPerPrompt:  int32(c.LimitMMPerPrompt.LimitAudioPerPrompt),
-		MMProj:               c.MMProj,
-		FlashAttention:       c.FlashAttention,
-		CacheTypeKey:         c.CacheTypeK,
-		CacheTypeValue:       c.CacheTypeV,
-		NoKVOffload:          c.NoKVOffloading,
-		YarnExtFactor:        c.YarnExtFactor,
-		YarnAttnFactor:       c.YarnAttnFactor,
-		YarnBetaFast:         c.YarnBetaFast,
-		YarnBetaSlow:         c.YarnBetaSlow,
-		NGQA:                 c.NGQA,
-		RMSNormEps:           c.RMSNormEps,
-		MLock:                mmlock,
-		RopeFreqBase:         c.RopeFreqBase,
-		RopeScaling:          c.RopeScaling,
-		Type:                 c.ModelType,
-		RopeFreqScale:        c.RopeFreqScale,
-		NUMA:                 c.NUMA,
-		Embeddings:           embeddings,
-		LowVRAM:              lowVRAM,
-		NGPULayers:           int32(nGPULayers),
-		MMap:                 mmap,
-		MainGPU:              c.MainGPU,
-		Threads:              int32(*c.Threads),
-		TensorSplit:          c.TensorSplit,
+		LimitImagePerPrompt: int32(c.LimitMMPerPrompt.LimitImagePerPrompt),
+		LimitVideoPerPrompt: int32(c.LimitMMPerPrompt.LimitVideoPerPrompt),
+		LimitAudioPerPrompt: int32(c.LimitMMPerPrompt.LimitAudioPerPrompt),
+		MMProj:              c.MMProj,
+		FlashAttention:      c.FlashAttention,
+		CacheTypeKey:        c.CacheTypeK,
+		CacheTypeValue:      c.CacheTypeV,
+		NoKVOffload:         c.NoKVOffloading,
+		YarnExtFactor:       c.YarnExtFactor,
+		YarnAttnFactor:      c.YarnAttnFactor,
+		YarnBetaFast:        c.YarnBetaFast,
+		YarnBetaSlow:        c.YarnBetaSlow,
+		NGQA:                c.NGQA,
+		RMSNormEps:          c.RMSNormEps,
+		MLock:               mmlock,
+		RopeFreqBase:        c.RopeFreqBase,
+		RopeScaling:         c.RopeScaling,
+		Type:                c.ModelType,
+		RopeFreqScale:       c.RopeFreqScale,
+		NUMA:                c.NUMA,
+		Embeddings:          embeddings,
+		LowVRAM:             lowVRAM,
+		NGPULayers:          int32(nGPULayers),
+		MMap:                mmap,
+		MainGPU:             c.MainGPU,
+		Threads:             int32(*c.Threads),
+		TensorSplit:         c.TensorSplit,
 		// AutoGPTQ
 		ModelBaseName:    c.AutoGPTQ.ModelBaseName,
 		Device:           c.AutoGPTQ.Device,

core/backend/rerank.go

@@ -12,10 +12,10 @@ import (
 func Rerank(request *proto.RerankRequest, loader *model.ModelLoader, appConfig *config.ApplicationConfig, backendConfig config.BackendConfig) (*proto.RerankResult, error) {
 	opts := ModelOptions(backendConfig, appConfig)
 	rerankModel, err := loader.Load(opts...)
-
 	if err != nil {
 		return nil, err
 	}
+	defer loader.Close()
 
 	if rerankModel == nil {
 		return nil, fmt.Errorf("could not load rerank model")

core/backend/soundgeneration.go

@@ -26,10 +26,10 @@ func SoundGeneration(
 
 	opts := ModelOptions(backendConfig, appConfig)
 	soundGenModel, err := loader.Load(opts...)
-
 	if err != nil {
 		return "", nil, err
 	}
+	defer loader.Close()
 
 	if soundGenModel == nil {
 		return "", nil, fmt.Errorf("could not load sound generation model")

core/backend/token_metrics.go

@@ -20,6 +20,7 @@ func TokenMetrics(
 	if err != nil {
 		return nil, err
 	}
+	defer loader.Close()
 
 	if model == nil {
 		return nil, fmt.Errorf("could not loadmodel model")

core/backend/tokenize.go

@@ -14,10 +14,10 @@ func ModelTokenize(s string, loader *model.ModelLoader, backendConfig config.Bac
 
 	opts := ModelOptions(backendConfig, appConfig)
 	inferenceModel, err = loader.Load(opts...)
-
 	if err != nil {
 		return schema.TokenizeResponse{}, err
 	}
+	defer loader.Close()
 
 	predictOptions := gRPCPredictOpts(backendConfig, loader.ModelPath)
 	predictOptions.Prompt = s

core/backend/transcript.go

@@ -24,6 +24,7 @@ func ModelTranscription(audio, language string, translate bool, ml *model.ModelL
 	if err != nil {
 		return nil, err
 	}
+	defer ml.Close()
 
 	if transcriptionModel == nil {
 		return nil, fmt.Errorf("could not load transcription model")

core/backend/tts.go

@@ -23,10 +23,10 @@ func ModelTTS(
 ) (string, *proto.Result, error) {
 	opts := ModelOptions(backendConfig, appConfig, model.WithDefaultBackendString(model.PiperBackend))
 	ttsModel, err := loader.Load(opts...)
-
 	if err != nil {
 		return "", nil, err
 	}
+	defer loader.Close()
 
 	if ttsModel == nil {
 		return "", nil, fmt.Errorf("could not load tts model %q", backendConfig.Model)

core/backend/vad.go

@@ -19,6 +19,8 @@ func VAD(request *schema.VADRequest,
 	if err != nil {
 		return nil, err
 	}
+	defer ml.Close()
+
 	req := proto.VADRequest{
 		Audio: request.Audio,
 	}

core/cli/soundgeneration.go

@@ -74,7 +74,7 @@ func (t *SoundGenerationCMD) Run(ctx *cliContext.Context) error {
 		AssetsDestination:    t.BackendAssetsPath,
 		ExternalGRPCBackends: externalBackends,
 	}
-	ml := model.NewModelLoader(opts.ModelPath)
+	ml := model.NewModelLoader(opts.ModelPath, opts.SingleBackend)
 
 	defer func() {
 		err := ml.StopAllGRPC()

core/cli/transcript.go

@@ -32,7 +32,7 @@ func (t *TranscriptCMD) Run(ctx *cliContext.Context) error {
 	}
 
 	cl := config.NewBackendConfigLoader(t.ModelsPath)
-	ml := model.NewModelLoader(opts.ModelPath)
+	ml := model.NewModelLoader(opts.ModelPath, opts.SingleBackend)
 	if err := cl.LoadBackendConfigsFromPath(t.ModelsPath); err != nil {
 		return err
 	}

core/cli/tts.go

@@ -41,7 +41,7 @@ func (t *TTSCMD) Run(ctx *cliContext.Context) error {
 		AudioDir:          outputDir,
 		AssetsDestination: t.BackendAssetsPath,
 	}
-	ml := model.NewModelLoader(opts.ModelPath)
+	ml := model.NewModelLoader(opts.ModelPath, opts.SingleBackend)
 
 	defer func() {
 		err := ml.StopAllGRPC()

core/http/endpoints/localai/stores.go

@@ -21,6 +21,7 @@ func StoresSetEndpoint(sl *model.ModelLoader, appConfig *config.ApplicationConfi
 		if err != nil {
 			return err
 		}
+		defer sl.Close()
 
 		vals := make([][]byte, len(input.Values))
 		for i, v := range input.Values {
@@ -48,6 +49,7 @@ func StoresDeleteEndpoint(sl *model.ModelLoader, appConfig *config.ApplicationCo
 		if err != nil {
 			return err
 		}
+		defer sl.Close()
 
 		if err := store.DeleteCols(c.Context(), sb, input.Keys); err != nil {
 			return err
@@ -69,6 +71,7 @@ func StoresGetEndpoint(sl *model.ModelLoader, appConfig *config.ApplicationConfi
 		if err != nil {
 			return err
 		}
+		defer sl.Close()
 
 		keys, vals, err := store.GetCols(c.Context(), sb, input.Keys)
 		if err != nil {
@@ -100,6 +103,7 @@ func StoresFindEndpoint(sl *model.ModelLoader, appConfig *config.ApplicationConf
 		if err != nil {
 			return err
 		}
+		defer sl.Close()
 
 		keys, vals, similarities, err := store.Find(c.Context(), sb, input.Key, input.Topk)
 		if err != nil {

core/http/endpoints/openai/assistant_test.go

@@ -40,7 +40,7 @@ func TestAssistantEndpoints(t *testing.T) {
 	cl := &config.BackendConfigLoader{}
 	//configsDir := "/tmp/localai/configs"
 	modelPath := "/tmp/localai/model"
-	var ml = model.NewModelLoader(modelPath)
+	var ml = model.NewModelLoader(modelPath, false)
 
 	appConfig := &config.ApplicationConfig{
 		ConfigsDir:    configsDir,

core/http/routes/localai.go

@@ -50,11 +50,10 @@ func RegisterLocalAIRoutes(router *fiber.App,
 	router.Post("/v1/vad", vadChain...)
 
 	// Stores
-	sl := model.NewModelLoader("")
-	router.Post("/stores/set", localai.StoresSetEndpoint(sl, appConfig))
-	router.Post("/stores/delete", localai.StoresDeleteEndpoint(sl, appConfig))
-	router.Post("/stores/get", localai.StoresGetEndpoint(sl, appConfig))
-	router.Post("/stores/find", localai.StoresFindEndpoint(sl, appConfig))
+	router.Post("/stores/set", localai.StoresSetEndpoint(ml, appConfig))
+	router.Post("/stores/delete", localai.StoresDeleteEndpoint(ml, appConfig))
+	router.Post("/stores/get", localai.StoresGetEndpoint(ml, appConfig))
+	router.Post("/stores/find", localai.StoresFindEndpoint(ml, appConfig))
 
 	if !appConfig.DisableMetrics {
 		router.Get("/metrics", localai.LocalAIMetricsEndpoint())

pkg/model/initializers.go

@@ -509,7 +509,23 @@ func (ml *ModelLoader) stopActiveBackends(modelID string, singleActiveBackend bo
 	}
 }
 
+func (ml *ModelLoader) Close() {
+	if !ml.singletonMode {
+		return
+	}
+	ml.singletonLock.Unlock()
+}
+
+func (ml *ModelLoader) lockBackend() {
+	if !ml.singletonMode {
+		return
+	}
+	ml.singletonLock.Lock()
+}
+
 func (ml *ModelLoader) Load(opts ...Option) (grpc.Backend, error) {
+	ml.lockBackend() // grab the singleton lock if needed
+
 	o := NewOptions(opts...)
 
 	// Return earlier if we have a model already loaded
@@ -520,7 +536,7 @@ func (ml *ModelLoader) Load(opts ...Option) (grpc.Backend, error) {
 		return m.GRPC(o.parallelRequests, ml.wd), nil
 	}
 
-	ml.stopActiveBackends(o.modelID, o.singleActiveBackend)
+	ml.stopActiveBackends(o.modelID, ml.singletonMode)
 
 	// if a backend is defined, return the loader directly
 	if o.backendString != "" {
@@ -533,6 +549,7 @@ func (ml *ModelLoader) Load(opts ...Option) (grpc.Backend, error) {
 	// get backends embedded in the binary
 	autoLoadBackends, err := ml.ListAvailableBackends(o.assetDir)
 	if err != nil {
+		ml.Close() // we failed, release the lock
 		return nil, err
 	}
 
@@ -564,5 +581,7 @@ func (ml *ModelLoader) Load(opts ...Option) (grpc.Backend, error) {
 		}
 	}
 
+	ml.Close() // make sure to release the lock in case of failure
+
 	return nil, fmt.Errorf("could not load model - all backends returned error: %s", err.Error())
 }

pkg/model/loader.go

@@ -18,16 +18,19 @@ import (
 
 // TODO: Split ModelLoader and TemplateLoader? Just to keep things more organized. Left together to share a mutex until I look into that. Would split if we seperate directories for .bin/.yaml and .tmpl
 type ModelLoader struct {
-	ModelPath string
-	mu        sync.Mutex
-	models    map[string]*Model
-	wd        *WatchDog
+	ModelPath     string
+	mu            sync.Mutex
+	singletonLock sync.Mutex
+	singletonMode bool
+	models        map[string]*Model
+	wd            *WatchDog
 }
 
-func NewModelLoader(modelPath string) *ModelLoader {
+func NewModelLoader(modelPath string, singleActiveBackend bool) *ModelLoader {
 	nml := &ModelLoader{
-		ModelPath: modelPath,
-		models:    make(map[string]*Model),
+		ModelPath:     modelPath,
+		models:        make(map[string]*Model),
+		singletonMode: singleActiveBackend,
 	}
 
 	return nml

pkg/model/loader_options.go

@@ -17,10 +17,9 @@ type Options struct {
 
 	externalBackends map[string]string
 
-	grpcAttempts        int
-	grpcAttemptsDelay   int
-	singleActiveBackend bool
-	parallelRequests    bool
+	grpcAttempts      int
+	grpcAttemptsDelay int
+	parallelRequests  bool
 }
 
 type Option func(*Options)
@@ -88,12 +87,6 @@ func WithContext(ctx context.Context) Option {
 	}
 }
 
-func WithSingleActiveBackend() Option {
-	return func(o *Options) {
-		o.singleActiveBackend = true
-	}
-}
-
 func WithModelID(id string) Option {
 	return func(o *Options) {
 		o.modelID = id

pkg/model/loader_test.go

@@ -21,7 +21,7 @@ var _ = Describe("ModelLoader", func() {
 		// Setup the model loader with a test directory
 		modelPath = "/tmp/test_model_path"
 		os.Mkdir(modelPath, 0755)
-		modelLoader = model.NewModelLoader(modelPath)
+		modelLoader = model.NewModelLoader(modelPath, false)
 	})
 
 	AfterEach(func() {