[BugFix] Fix tokenize asyncio task leak (#24677)

Signed-off-by: Nick Hill <nhill@redhat.com>

vllm/entrypoints/renderer.py

@@ -168,8 +168,8 @@ class BaseRenderer(ABC):
 
         if isinstance(prompt_embeds, list):
             return [_load_and_validate_embed(embed) for embed in prompt_embeds]
-        else:
-            return [_load_and_validate_embed(prompt_embeds)]
+
+        return [_load_and_validate_embed(prompt_embeds)]
 
 
 class CompletionRenderer(BaseRenderer):
@@ -182,7 +182,7 @@ class CompletionRenderer(BaseRenderer):
                                             AsyncMicrobatchTokenizer]] = None,
     ):
         super().__init__(model_config, tokenizer)
-        self.async_tokenizer_pool = async_tokenizer_pool or {}
+        self.async_tokenizer_pool = async_tokenizer_pool
         self.async_tokenizer: Optional[AsyncMicrobatchTokenizer] = None
 
     async def render_prompt(
@@ -208,23 +208,21 @@ class CompletionRenderer(BaseRenderer):
         for prompt_input in batch_inputs:
             if prompt_input["is_tokens"] is True:
                 # Token input
-                detokenize_task = asyncio.create_task(
-                    # Note: detokenization is needed when echo is enabled,
-                    # where the input token IDs are decoded back to text.
-                    self._maybe_detokenize(prompt_input["content"],
-                                           config.max_length,
-                                           truncate_prompt_tokens,
-                                           config.cache_salt,
-                                           config.needs_detokenization))
-                tasks.append(detokenize_task)
+                # Note: detokenization is needed when echo is enabled,
+                # where the input token IDs are decoded back to text.
+                task = self._maybe_detokenize(prompt_input["content"],
+                                              config.max_length,
+                                              truncate_prompt_tokens,
+                                              config.cache_salt,
+                                              config.needs_detokenization)
             else:
                 # Text input
-                tokenize_task = asyncio.create_task(
-                    self._tokenize(prompt_input["content"], config.max_length,
-                                   truncate_prompt_tokens,
-                                   config.add_special_tokens,
-                                   config.cache_salt))
-                tasks.append(tokenize_task)
+                task = self._tokenize(prompt_input["content"],
+                                      config.max_length,
+                                      truncate_prompt_tokens,
+                                      config.add_special_tokens,
+                                      config.cache_salt)
+            tasks.append(task)
 
         # Wait for all text tokenization to finish
         if tasks:
@@ -356,20 +354,24 @@ class CompletionRenderer(BaseRenderer):
 
     def _get_async_tokenizer(self) -> AsyncMicrobatchTokenizer:
         """Get or create async tokenizer using shared pool."""
-        if self.async_tokenizer is not None:
-            return self.async_tokenizer
+        async_tokenizer = self.async_tokenizer
+        if async_tokenizer is not None:
+            return async_tokenizer
+
+        tokenizer = self.tokenizer
         if self.tokenizer is None:
             raise ValueError(
                 "No tokenizer available for text input processing")
 
-        # Check shared pool first
-        if self.tokenizer in self.async_tokenizer_pool:
-            return self.async_tokenizer_pool[self.tokenizer]
-
-        # Create new async tokenizer and add to pool
-        self.async_tokenizer = AsyncMicrobatchTokenizer(self.tokenizer)
-        self.async_tokenizer_pool[self.tokenizer] = self.async_tokenizer
-        return self.async_tokenizer
+        if self.async_tokenizer_pool is None:
+            async_tokenizer = AsyncMicrobatchTokenizer(tokenizer)
+        else:
+            async_tokenizer = self.async_tokenizer_pool.get(tokenizer)
+            if async_tokenizer is None:
+                async_tokenizer = AsyncMicrobatchTokenizer(tokenizer)
+                self.async_tokenizer_pool[tokenizer] = async_tokenizer
+        self.async_tokenizer = async_tokenizer
+        return async_tokenizer
 
     def _create_tokens_prompt(
         self,