[Frontend][Model] Support batch request with refined OmniDiffusionReq… (#797)

Signed-off-by: Huang, Zeyu <11222265+fhfuih@users.noreply.github.com>

docs/getting_started/quickstart.md

@@ -46,6 +46,46 @@ if __name__ == "__main__":
     images[0].save("coffee.png")
 ```
 
+You can pass a list of prompts and wait for them to process altogether, shown below.
+
+!!! info
+
+    However, it is not currently recommended to do so
+    because not all models support batch inference,
+    and batch requesting mostly does not provide significant performance improvement (despite the impression that it does).
+    This feature is primarily for the sake of interface compatibility with vLLM and to allow for future improvements.
+
+```python
+from vllm_omni.entrypoints.omni import Omni
+
+if __name__ == "__main__":
+    omni = Omni(
+        model="Tongyi-MAI/Z-Image-Turbo",
+        # stage_configs_path="./stage-config.yaml",  # See below
+    )
+    prompts = [
+        "a cup of coffee on a table",
+        "a toy dinosaur on a sandy beach",
+        "a fox waking up in bed and yawning",
+    ]
+    omni_outputs = omni.generate(prompts)
+    for i_prompt, prompt_output in enumerate(omni_outputs):
+        this_request_output = prompt_output.request_output[0]
+        this_images = this_request_output.images
+        for i_image, image in enumerate(this_images):
+            image.save(f"p{i_prompt}-img{i_image}.jpg")
+            print("saved to", f"p{i_prompt}-img{i_image}.jpg")
+            # saved to p0-img0.jpg
+            # saved to p1-img0.jpg
+            # saved to p2-img0.jpg
+```
+
+!!! info
+
+    For diffusion pipelines, the stage config field `stage_args.[].runtime.max_batch_size` is 1 by default, and the input
+    list is sliced into single-item requests before feeding into the diffusion pipeline. For models that do internally support
+    batched inputs, you can [modify this configuration](../configuration/stage_configs.md) to let the model accept a longer batch of prompts.
+
 For more usages, please refer to [offline inference](../user_guide/examples/offline_inference/qwen2_5_omni.md)
 
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