[Fix] Better error message when there is OOM during cache initialization (#203)

Author: zhuohan123

vllm/engine/llm_engine.py

@@ -127,6 +127,12 @@ def _init_cache(self) -> None:
         # FIXME(woosuk): Change to debug log.
         logger.info(f'# GPU blocks: {num_gpu_blocks}, '
                     f'# CPU blocks: {num_cpu_blocks}')
+
+        if num_gpu_blocks <= 0 or num_cpu_blocks <= 0:
+            raise ValueError("No available memory for the cache blocks. "
+                             "Try increasing `gpu_memory_utilization` when "
+                             "initializing the engine.")
+
         self.cache_config.num_gpu_blocks = num_gpu_blocks
         self.cache_config.num_cpu_blocks = num_cpu_blocks
 

vllm/outputs.py

@@ -53,6 +53,7 @@ class RequestOutput:
         prompt: The prompt string of the request.
         prompt_token_ids: The token IDs of the prompt.
         outputs: The output sequences of the request.
+        finished: Whether the whole request is finished.
     """
     def __init__(
         self,