fix: process T2I batch sequentially to prevent CUDA out of memory err…

…ors (livepeer#66)

This commit ensures that batches in the T2I pipeline are processed sequentially. This change is necessary because we currently lack the ability to estimate a GPU's VRAM capacity and manage requests accordingly.

* process text-to-image requested image count sequentially

* refactor: cleanup sequential images code

This commit cleans up the sequential images code a bit.

---------

Co-authored-by: Rick Staa <[email protected]>

runner/app/routes/text_to_image.py

@@ -7,7 +7,7 @@
 from app.routes.util import image_to_data_url, ImageResponse, HTTPError, http_error
 import logging
 import random
-import os
+import os, json
 
 router = APIRouter()
 
@@ -57,33 +57,32 @@ async def text_to_image(
             ),
         )
 
-    if params.seed is None:
-        params.seed = random.randint(0, 2**32 - 1)
-    if params.num_images_per_prompt > 1:
-        params.seed = [
-            i for i in range(params.seed, params.seed + params.num_images_per_prompt)
-        ]
+    seed = params.seed if params.seed is not None else random.randint(0, 2**32 - 1)
+    seeds = [seed + i for i in range(params.num_images_per_prompt)]
 
-    try:
-        images, has_nsfw_concept = pipeline(**params.model_dump())
-    except Exception as e:
-        logger.error(f"TextToImagePipeline error: {e}")
-        logger.exception(e)
-        return JSONResponse(
-            status_code=500, content=http_error("TextToImagePipeline error")
-        )
-
-    seeds = params.seed
-    if not isinstance(seeds, list):
-        seeds = [seeds]
+    # TODO: Process one image at a time to avoid CUDA OEM errors. Can be removed again
+    # once LIV-243 and LIV-379 are resolved.
+    images = []
+    has_nsfw_concept = []
+    params.num_images_per_prompt = 1
+    for seed in seeds:
+        try:
+            params.seed = [seed]
+            imgs, nsfw_check = pipeline(**params.model_dump())
+            images.extend(imgs)
+            has_nsfw_concept.extend(nsfw_check)
+        except Exception as e:
+            logger.error(f"TextToImagePipeline error: {e}")
+            logger.exception(e)
+            return JSONResponse(
+                status_code=500, content=http_error("TextToImagePipeline error")
+            )
 
-    output_images = []
-    for img, sd, is_nsfw in zip(images, seeds, has_nsfw_concept):
-        # TODO: Return None once Go codegen tool supports optional properties
-        # OAPI 3.1 https://github.com/deepmap/oapi-codegen/issues/373
-        is_nsfw = is_nsfw or False
-        output_images.append(
-            {"url": image_to_data_url(img), "seed": sd, "nsfw": is_nsfw}
-        )
+    # TODO: Return None once Go codegen tool supports optional properties
+    # OAPI 3.1 https://github.com/deepmap/oapi-codegen/issues/373
+    output_images = [
+        {"url": image_to_data_url(img), "seed": sd, "nsfw": nsfw or False}
+        for img, sd, nsfw in zip(images, seeds, has_nsfw_concept)
+    ]
 
     return {"images": output_images}