From 1508b1692a33097197a86ff262c10d5c69d19f0f Mon Sep 17 00:00:00 2001
From: Roy <jasonailu87@gmail.com>
Date: Thu, 21 Mar 2024 18:07:48 +0800
Subject: [PATCH] [Misc][Log] Add log for tokenizer length not equal to
 vocabulary size (#3500)

---
 vllm/engine/llm_engine.py                 | 8 ++++++++
 vllm/entrypoints/openai/serving_engine.py | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/vllm/engine/llm_engine.py b/vllm/engine/llm_engine.py
index 2280481cc..b726cdd7a 100644
--- a/vllm/engine/llm_engine.py
+++ b/vllm/engine/llm_engine.py
@@ -169,6 +169,14 @@ def _init_tokenizer(self, **tokenizer_init_kwargs):
         self.tokenizer: BaseTokenizerGroup = get_tokenizer_group(
             self.parallel_config.tokenizer_pool_config, **init_kwargs)
 
+        if len(self.get_tokenizer()) != self.model_config.get_vocab_size():
+            logger.warning(
+                f"The tokenizer's vocabulary size {len(self.get_tokenizer())}"
+                f" does not match the model's vocabulary size "
+                f"{self.model_config.get_vocab_size()}. This might "
+                f"cause an error in decoding. Please change config.json "
+                "to match the tokenizer's vocabulary size.")
+
     def _verify_args(self) -> None:
         self.model_config.verify_with_parallel_config(self.parallel_config)
         self.cache_config.verify_with_parallel_config(self.parallel_config)
diff --git a/vllm/entrypoints/openai/serving_engine.py b/vllm/entrypoints/openai/serving_engine.py
index 2db884945..976046bee 100644
--- a/vllm/entrypoints/openai/serving_engine.py
+++ b/vllm/entrypoints/openai/serving_engine.py
@@ -68,6 +68,14 @@ async def _post_init(self):
             tokenizer_mode=engine_model_config.tokenizer_mode,
             trust_remote_code=engine_model_config.trust_remote_code)
 
+        if len(self.tokenizer) != engine_model_config.get_vocab_size():
+            logger.warning(
+                f"The tokenizer's vocabulary size {len(self.tokenizer)}"
+                f" does not match the model's vocabulary size "
+                f"{engine_model_config.get_vocab_size()}. This might "
+                f"cause an error in decoding. Please change config.json "
+                "to match the tokenizer's vocabulary size.")
+
     async def show_available_models(self) -> ModelList:
         """Show available models. Right now we only have one model."""
         model_cards = [