Create inference.py

code/inference.py

@@ -0,0 +1,162 @@
+import json
+import torch
+from transformers import AutoModelForCausalLM, AutoTokenizer
+from typing import List, Dict
+from accelerate import load_checkpoint_and_dispatch
+import fcntl  # For file locking
+import os  # For file operations
+import time  # For sleep function
+
+# Set the max_split_size globally at the start
+os.environ["PYTORCH_CUDA_ALLOC_CONF"] = "max_split_size_mb:128"
+
+# Print to verify the environment variable is correctly set
+print(f"PYTORCH_CUDA_ALLOC_CONF: {os.environ.get('PYTORCH_CUDA_ALLOC_CONF')}")
+
+# Global variables to persist the model and tokenizer between invocations
+model = None
+tokenizer = None
+
+# Function to format chat messages using Qwen's chat template
+def format_chat(messages: List[Dict[str, str]], tokenizer) -> str:
+    """
+    Format chat messages using Qwen's chat template.
+    """
+    return tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
+
+def model_fn(model_dir, context=None):
+    global model, tokenizer
+
+    # Path to lock file for ensuring single loading
+    lock_file = "/tmp/model_load.lock"
+    # Path to in-progress file indicating model loading is happening
+    in_progress_file = "/tmp/model_loading_in_progress"
+
+    if model is not None and tokenizer is not None:
+        print("Model and tokenizer already loaded, skipping reload.")
+        return model, tokenizer
+
+    # Attempt to acquire the lock
+    with open(lock_file, 'w') as lock:
+        print("Attempting to acquire model load lock...")
+        fcntl.flock(lock, fcntl.LOCK_EX)  # Exclusive lock
+
+        try:
+            # Check if another worker is in the process of loading
+            if os.path.exists(in_progress_file):
+                print("Another worker is currently loading the model, waiting...")
+
+                # Poll the in-progress flag until the other worker finishes loading
+                while os.path.exists(in_progress_file):
+                    time.sleep(5)  # Wait for 5 seconds before checking again
+
+                print("Loading complete by another worker, skipping reload.")
+                return model, tokenizer
+
+            # If no one is loading, start loading the model and set the in-progress flag
+            print("No one is loading, proceeding to load the model.")
+            with open(in_progress_file, 'w') as f:
+                f.write("loading")
+
+            # Loading the model and tokenizer
+            if model is None or tokenizer is None:
+                print("Loading the model and tokenizer...")
+
+                offload_dir = "/tmp/offload_dir"
+                os.makedirs(offload_dir, exist_ok=True)
+
+                # Load and dispatch model across 4 GPUs using tensor parallelism
+                model = AutoModelForCausalLM.from_pretrained(model_dir, torch_dtype=torch.float16)
+                model = load_checkpoint_and_dispatch(
+                    model,
+                    model_dir,
+                    device_map="auto",  # Automatically map layers across GPUs
+                    offload_folder=offload_dir,  # Offload parts to disk if needed
+                    max_memory = {i: "15GiB" for i in range(torch.cuda.device_count())}  # Example for reducing usage per GPU
+                    no_split_module_classes=["QwenForCausalLM"]  # Ensure model is split across the GPUs
+                )
+
+                # Load the tokenizer
+                tokenizer = AutoTokenizer.from_pretrained(model_dir)
+
+        except Exception as e:
+            print(f"Error loading model and tokenizer: {e}")
+            raise
+
+        finally:
+            # Remove the in-progress flag once the loading is complete
+            if os.path.exists(in_progress_file):
+                os.remove(in_progress_file)
+
+            # Release the lock
+            fcntl.flock(lock, fcntl.LOCK_UN)
+
+    return model, tokenizer
+
+# Custom predict function for SageMaker
+def predict_fn(input_data, model_and_tokenizer, context=None):
+    """
+    Generate predictions for the input data.
+    """
+    try:
+        model, tokenizer = model_and_tokenizer
+        data = json.loads(input_data)
+
+        # Format the prompt using Qwen's chat template
+        messages = data.get("messages", [])
+        formatted_prompt = format_chat(messages, tokenizer)
+
+        # Tokenize the input
+        inputs = tokenizer([formatted_prompt], return_tensors="pt").to("cuda:0")  # Send input to GPU 0 for generation
+
+        # Generate output
+        outputs = model.generate(
+            inputs['input_ids'],
+            max_new_tokens=data.get("max_new_tokens", 512),
+            temperature=data.get("temperature", 0.7),
+            top_p=data.get("top_p", 0.9),
+            repetition_penalty=data.get("repetition_penalty", 1.0),
+            length_penalty=data.get("length_penalty", 1.0),
+            do_sample=True
+        )
+
+        # Decode the output
+        generated_text = tokenizer.batch_decode(outputs, skip_special_tokens=True)[0]
+
+        # Build response
+        response = {
+            "id": "chatcmpl-uuid",
+            "object": "chat.completion",
+            "model": "qwen-72b",
+            "choices": [{
+                "index": 0,
+                "message": {
+                    "role": "assistant",
+                    "content": generated_text
+                },
+                "finish_reason": "stop"
+            }],
+            "usage": {
+                "prompt_tokens": len(inputs['input_ids'][0]),
+                "completion_tokens": len(outputs[0]),
+                "total_tokens": len(inputs['input_ids'][0]) + len(outputs[0])
+            }
+        }
+        return response
+
+    except Exception as e:
+        return {"error": str(e), "details": repr(e)}
+
+# Define input format for SageMaker
+def input_fn(serialized_input_data, content_type, context=None):
+    """
+    Prepare the input data for inference.
+    """
+    return serialized_input_data
+
+# Define output format for SageMaker
+def output_fn(prediction_output, accept, context=None):
+    """
+    Convert the model output to a JSON response.
+    """
+    return json.dumps(prediction_output)