Merge pull request #4294 from dhiltgen/harden_subprocess_reaping

Harden subprocess reaping

llm/server.go

@@ -53,6 +53,7 @@ type llmServer struct {
 	estimatedTotal uint64 // Total size of model
 	totalLayers    uint64
 	gpuCount       int
+	loadDuration   time.Duration // Record how long it took the model to load
 
 	sem *semaphore.Weighted
 }
@@ -291,6 +292,7 @@ func NewLlamaServer(gpus gpu.GpuInfoList, model string, ggml *GGML, adapters, pr
 			sem:            semaphore.NewWeighted(int64(numParallel)),
 			totalLayers:    ggml.KV().BlockCount() + 1,
 			gpuCount:       gpuCount,
+			done:           make(chan error, 1),
 		}
 
 		s.cmd.Env = os.Environ()
@@ -339,6 +341,11 @@ func NewLlamaServer(gpus gpu.GpuInfoList, model string, ggml *GGML, adapters, pr
 			continue
 		}
 
+		// reap subprocess when it exits
+		go func() {
+			s.done <- s.cmd.Wait()
+		}()
+
 		return s, nil
 	}
 
@@ -483,13 +490,11 @@ func (s *llmServer) Ping(ctx context.Context) error {
 
 func (s *llmServer) WaitUntilRunning(ctx context.Context) error {
 	start := time.Now()
-	// TODO we need to wire up a better way to detect hangs during model load and startup of the server
 	expiresAt := time.Now().Add(10 * time.Minute) // be generous with timeout, large models can take a while to load
-	ticker := time.NewTicker(50 * time.Millisecond)
-	defer ticker.Stop()
 
 	slog.Info("waiting for llama runner to start responding")
 	var lastStatus ServerStatus = -1
+
 	for {
 		select {
 		case <-ctx.Done():
@@ -501,41 +506,39 @@ func (s *llmServer) WaitUntilRunning(ctx context.Context) error {
 				msg = s.status.LastErrMsg
 			}
 			return fmt.Errorf("llama runner process has terminated: %v %s", err, msg)
-		case <-ticker.C:
-			if time.Now().After(expiresAt) {
-				// timeout
-				msg := ""
-				if s.status != nil && s.status.LastErrMsg != "" {
-					msg = s.status.LastErrMsg
-				}
-				return fmt.Errorf("timed out waiting for llama runner to start: %s", msg)
+		default:
+		}
+		if time.Now().After(expiresAt) {
+			// timeout
+			msg := ""
+			if s.status != nil && s.status.LastErrMsg != "" {
+				msg = s.status.LastErrMsg
 			}
-			if s.cmd.ProcessState != nil {
-				msg := ""
-				if s.status != nil && s.status.LastErrMsg != "" {
-					msg = s.status.LastErrMsg
-				}
-				return fmt.Errorf("llama runner process no longer running: %d %s", s.cmd.ProcessState.ExitCode(), msg)
-			}
-
-			c, cancel := context.WithTimeout(ctx, 200*time.Millisecond)
-			defer cancel()
-			status, err := s.getServerStatus(c)
-			if err != nil && lastStatus != status {
-				slog.Debug("server not yet available", "error", err)
-				lastStatus = status
-				continue
-			}
-
-			switch status {
-			case ServerStatusLoadingModel:
-				// TODO - this state never seems to happen with the current server.cpp code (bug?)
-				// it doesn't respond to the health endpoint until after the model is loaded
-				slog.Debug("loading model")
-			case ServerStatusReady:
-				slog.Debug(fmt.Sprintf("llama runner started in %f seconds", time.Since(start).Seconds()))
-				return nil
+			return fmt.Errorf("timed out waiting for llama runner to start: %s", msg)
+		}
+		if s.cmd.ProcessState != nil {
+			msg := ""
+			if s.status != nil && s.status.LastErrMsg != "" {
+				msg = s.status.LastErrMsg
 			}
+			return fmt.Errorf("llama runner process no longer running: %d %s", s.cmd.ProcessState.ExitCode(), msg)
+		}
+		ctx, cancel := context.WithTimeout(ctx, 200*time.Millisecond)
+		defer cancel()
+		status, _ := s.getServerStatus(ctx)
+		if lastStatus != status && status != ServerStatusReady {
+			// Only log on status changes
+			slog.Info("waiting for server to become available", "status", status.ToString())
+		}
+		switch status {
+		case ServerStatusReady:
+			s.loadDuration = time.Since(start)
+			slog.Info(fmt.Sprintf("llama runner started in %0.2f seconds", s.loadDuration.Seconds()))
+			return nil
+		default:
+			lastStatus = status
+			time.Sleep(time.Millisecond * 250)
+			continue
 		}
 	}
 }
@@ -943,8 +946,11 @@ func (s *llmServer) Close() error {
 		if err := s.cmd.Process.Kill(); err != nil {
 			return err
 		}
-
-		_ = s.cmd.Wait()
+		// if ProcessState is already populated, Wait already completed, no need to wait again
+		if s.cmd.ProcessState == nil {
+			slog.Debug("waiting for llama server to exit")
+			<-s.done
+		}
 
 		slog.Debug("llama server stopped")
 	}