fix(ai): improve AI selection algorithm (#3030)

* fix(ai): improve selection algorithm

This commit modifies the selection algorithm to continue retrying for a
duration of one second instead of stopping after four attempts. This
change addresses issues encountered with the current algorithm's
performance in environments with 15 nodes on the network, ensuring more
robust and reliable operation until further optimizations can be
implemented.

* refactor(ai): enhance selection algorithm retry logic

This commit replaces the time-based for-loop in the selection
algorithm's retry logic with a more context-aware approach.

server/ai_process.go

@@ -12,6 +12,7 @@ import (
 	"net/http"
 	"path/filepath"
 	"strings"
+	"time"
 
 	"github.com/livepeer/ai-worker/worker"
 	"github.com/livepeer/go-livepeer/clog"
@@ -21,7 +22,7 @@ import (
 	"github.com/livepeer/lpms/stream"
 )
 
-const maxProcessingRetries = 4
+const processingRetryTimeout = 2 * time.Second
 const defaultTextToImageModelID = "stabilityai/sdxl-turbo"
 const defaultImageToImageModelID = "stabilityai/sdxl-turbo"
 const defaultImageToVideoModelID = "stabilityai/stable-video-diffusion-img2vid-xt"
@@ -311,8 +312,11 @@ func processAIRequest(ctx context.Context, params aiRequestParams, req interface
 
 	var resp *worker.ImageResponse
 
+	cctx, cancel := context.WithTimeout(context.Background(), processingRetryTimeout)
+	defer cancel()
+
 	tries := 0
-	for tries < maxProcessingRetries {
+	for {
 		tries++
 
 		sess, err := params.sessManager.Select(ctx, cap, modelID)
@@ -334,6 +338,10 @@ func processAIRequest(ctx context.Context, params aiRequestParams, req interface
 		clog.Infof(ctx, "Error submitting request cap=%v modelID=%v try=%v orch=%v err=%v", cap, modelID, tries, sess.Transcoder(), err)
 
 		params.sessManager.Remove(ctx, sess)
+
+		if cctx.Err() == context.DeadlineExceeded {
+			break
+		}
 	}
 
 	if resp == nil {