app: gracefully shut down ollama serve on windows (#3641)

* app: gracefully shut down `ollama serve` on windows

* fix linter errors

* bring back `HideWindow`

* remove creation flags

* restore `windows.CREATE_NEW_PROCESS_GROUP`

app/lifecycle/server.go

@@ -9,7 +9,6 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
-	"syscall"
 	"time"
 
 	"github.com/ollama/ollama/api"
@@ -87,19 +86,29 @@ func SpawnServer(ctx context.Context, command string) (chan int, error) {
 	// Re-wire context done behavior to attempt a graceful shutdown of the server
 	cmd.Cancel = func() error {
 		if cmd.Process != nil {
-			cmd.Process.Signal(os.Interrupt) //nolint:errcheck
+			err := terminate(cmd)
+			if err != nil {
+				slog.Warn("error trying to gracefully terminate server", "err", err)
+				return cmd.Process.Kill()
+			}
+
 			tick := time.NewTicker(10 * time.Millisecond)
 			defer tick.Stop()
+
 			for {
 				select {
 				case <-tick.C:
-					// OS agnostic "is it still running"
-					if proc, err := os.FindProcess(int(cmd.Process.Pid)); err != nil || errors.Is(proc.Signal(syscall.Signal(0)), os.ErrProcessDone) {
-						return nil //nolint:nilerr
+					exited, err := isProcessExited(cmd.Process.Pid)
+					if err != nil {
+						return err
+					}
+
+					if exited {
+						return nil
 					}
 				case <-time.After(5 * time.Second):
 					slog.Warn("graceful server shutdown timeout, killing", "pid", cmd.Process.Pid)
-					cmd.Process.Kill() //nolint:errcheck
+					return cmd.Process.Kill()
 				}
 			}
 		}