[Misc] Make cached tokenizer pickle-compatible (#17048)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

benchmarks/benchmark_prefix_caching.py

@@ -63,14 +63,16 @@ class Request:
     output_len: int
 
 
-def sample_tokens(tokenizer: PreTrainedTokenizerBase, length: int) -> str:
+def sample_tokens(tokenizer: PreTrainedTokenizerBase,
+                  length: int) -> list[int]:
     vocab = tokenizer.get_vocab()
+    all_special_ids = set(tokenizer.all_special_ids)
+
     # Remove the special tokens.
-    vocab = {
-        k: v
-        for k, v in vocab.items() if k not in tokenizer.all_special_ids
-    }
-    return random.choices(list(vocab.values()), k=length)
+    return random.choices(
+        [v for k, v in vocab.items() if k not in all_special_ids],
+        k=length,
+    )
 
 
 def sample_requests_from_dataset(

tests/tokenization/test_cached_tokenizer.py

 # SPDX-License-Identifier: Apache-2.0
-
+import pickle
 from copy import deepcopy
 
+import pytest
 from transformers import AutoTokenizer
 
-from vllm.transformers_utils.tokenizer import get_cached_tokenizer
+from vllm.transformers_utils.tokenizer import (AnyTokenizer,
+                                               get_cached_tokenizer)
 
 
-def test_cached_tokenizer():
-    reference_tokenizer = AutoTokenizer.from_pretrained("gpt2")
+@pytest.mark.parametrize("model_id", ["gpt2", "THUDM/chatglm3-6b"])
+def test_cached_tokenizer(model_id: str):
+    reference_tokenizer = AutoTokenizer.from_pretrained(model_id,
+                                                        trust_remote_code=True)
     reference_tokenizer.add_special_tokens({"cls_token": "<CLS>"})
     reference_tokenizer.add_special_tokens(
         {"additional_special_tokens": ["<SEP>"]})
+
     cached_tokenizer = get_cached_tokenizer(deepcopy(reference_tokenizer))
+    _check_consistency(cached_tokenizer, reference_tokenizer)
+
+    pickled_tokenizer = pickle.dumps(cached_tokenizer)
+    unpickled_tokenizer = pickle.loads(pickled_tokenizer)
+    _check_consistency(unpickled_tokenizer, reference_tokenizer)
+
+
+def _check_consistency(target: AnyTokenizer, expected: AnyTokenizer):
+    assert isinstance(target, type(expected))
+
+    # Cached attributes
+    assert target.all_special_ids == expected.all_special_ids
+    assert target.all_special_tokens == expected.all_special_tokens
+    assert (target.all_special_tokens_extended ==
+            expected.all_special_tokens_extended)
+    assert target.get_vocab() == expected.get_vocab()
+    assert len(target) == len(expected)
+
+    # Other attributes
+    assert getattr(target, "padding_side",
+                   None) == getattr(expected, "padding_side", None)
 
-    assert reference_tokenizer.encode("prompt") == cached_tokenizer.encode(
-        "prompt")
-    assert set(reference_tokenizer.all_special_ids) == set(
-        cached_tokenizer.all_special_ids)
-    assert set(reference_tokenizer.all_special_tokens) == set(
-        cached_tokenizer.all_special_tokens)
-    assert set(reference_tokenizer.all_special_tokens_extended) == set(
-        cached_tokenizer.all_special_tokens_extended)
+    assert target.encode("prompt") == expected.encode("prompt")

vllm/transformers_utils/tokenizer.py

 # SPDX-License-Identifier: Apache-2.0
 
 import contextlib
+import copy
 import os
 import warnings
 from functools import lru_cache
@@ -70,18 +71,17 @@ def encode_tokens(
 
 
 def get_cached_tokenizer(tokenizer: AnyTokenizer) -> AnyTokenizer:
-    """Get tokenizer with cached properties.
-
-    This will patch the tokenizer object in place.
-
+    """
     By default, transformers will recompute multiple tokenizer properties
-    each time they are called, leading to a significant slowdown. This
-    function caches these properties for faster access."""
+    each time they are called, leading to a significant slowdown.
+    This proxy caches these properties for faster access.
+    """
+    cached_tokenizer = copy.copy(tokenizer)
 
-    tokenizer_all_special_ids = set(tokenizer.all_special_ids)
+    tokenizer_all_special_ids = tokenizer.all_special_ids
+    tokenizer_all_special_tokens = tokenizer.all_special_tokens
     tokenizer_all_special_tokens_extended = (
         tokenizer.all_special_tokens_extended)
-    tokenizer_all_special_tokens = set(tokenizer.all_special_tokens)
     tokenizer_vocab = tokenizer.get_vocab()
     tokenizer_len = len(tokenizer)
 
@@ -97,31 +97,34 @@ def get_cached_tokenizer(tokenizer: AnyTokenizer) -> AnyTokenizer:
     class CachedTokenizer(tokenizer.__class__):  # type: ignore
 
         @property
-        def all_special_ids(self):
+        def all_special_ids(self) -> list[int]:
             return tokenizer_all_special_ids
 
         @property
-        def all_special_tokens(self):
+        def all_special_tokens(self) -> list[str]:
             return tokenizer_all_special_tokens
 
         @property
-        def all_special_tokens_extended(self):
+        def all_special_tokens_extended(self) -> list[str]:
             return tokenizer_all_special_tokens_extended
 
         @property
-        def max_token_id(self):
+        def max_token_id(self) -> int:
             return max_token_id
 
-        def get_vocab(self):
+        def get_vocab(self) -> dict[str, int]:
             return tokenizer_vocab
 
-        def __len__(self):
+        def __len__(self) -> int:
             return tokenizer_len
 
+        def __reduce__(self):
+            return get_cached_tokenizer, (tokenizer, )
+
     CachedTokenizer.__name__ = f"Cached{tokenizer.__class__.__name__}"
 
-    tokenizer.__class__ = CachedTokenizer
-    return tokenizer
+    cached_tokenizer.__class__ = CachedTokenizer
+    return cached_tokenizer
 
 
 def patch_padding_side(tokenizer: PreTrainedTokenizer) -> None:

vllm/transformers_utils/tokenizer_base.py

@@ -2,7 +2,7 @@
 
 import importlib
 from abc import ABC, abstractmethod
-from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple, Union
+from typing import TYPE_CHECKING, Any, Optional, Union
 
 if TYPE_CHECKING:
     from vllm.entrypoints.chat_utils import ChatCompletionMessageParam
@@ -12,17 +12,17 @@ class TokenizerBase(ABC):
 
     @property
     @abstractmethod
-    def all_special_tokens_extended(self) -> List[str]:
+    def all_special_tokens_extended(self) -> list[str]:
         raise NotImplementedError()
 
     @property
     @abstractmethod
-    def all_special_tokens(self) -> List[str]:
+    def all_special_tokens(self) -> list[str]:
         raise NotImplementedError()
 
     @property
     @abstractmethod
-    def all_special_ids(self) -> List[int]:
+    def all_special_ids(self) -> list[int]:
         raise NotImplementedError()
 
     @property
@@ -66,7 +66,7 @@ class TokenizerBase(ABC):
     @abstractmethod
     def __call__(
         self,
-        text: Union[str, List[str], List[int]],
+        text: Union[str, list[str], list[int]],
         text_pair: Optional[str] = None,
         add_special_tokens: bool = False,
         truncation: bool = False,
@@ -75,11 +75,11 @@ class TokenizerBase(ABC):
         raise NotImplementedError()
 
     @abstractmethod
-    def get_vocab(self) -> Dict[str, int]:
+    def get_vocab(self) -> dict[str, int]:
         raise NotImplementedError()
 
     @abstractmethod
-    def get_added_vocab(self) -> Dict[str, int]:
+    def get_added_vocab(self) -> dict[str, int]:
         raise NotImplementedError()
 
     @abstractmethod
@@ -88,44 +88,44 @@ class TokenizerBase(ABC):
         text: str,
         truncation: bool = False,
         max_length: Optional[int] = None,
-    ) -> List[int]:
+    ) -> list[int]:
         raise NotImplementedError()
 
     @abstractmethod
     def encode(self,
                text: str,
-               add_special_tokens: Optional[bool] = None) -> List[int]:
+               add_special_tokens: Optional[bool] = None) -> list[int]:
         raise NotImplementedError()
 
     @abstractmethod
     def apply_chat_template(self,
-                            messages: List["ChatCompletionMessageParam"],
-                            tools: Optional[List[Dict[str, Any]]] = None,
-                            **kwargs) -> List[int]:
+                            messages: list["ChatCompletionMessageParam"],
+                            tools: Optional[list[dict[str, Any]]] = None,
+                            **kwargs) -> list[int]:
         raise NotImplementedError()
 
     @abstractmethod
-    def convert_tokens_to_string(self, tokens: List[str]) -> str:
+    def convert_tokens_to_string(self, tokens: list[str]) -> str:
         raise NotImplementedError()
 
     @abstractmethod
     def decode(self,
-               ids: Union[List[int], int],
+               ids: Union[list[int], int],
                skip_special_tokens: bool = True) -> str:
         raise NotImplementedError()
 
     @abstractmethod
     def convert_ids_to_tokens(
         self,
-        ids: List[int],
+        ids: list[int],
         skip_special_tokens: bool = True,
-    ) -> List[str]:
+    ) -> list[str]:
         raise NotImplementedError()
 
 
 class TokenizerRegistry:
     # Tokenizer name -> (tokenizer module, tokenizer class)
-    REGISTRY: Dict[str, Tuple[str, str]] = {}
+    REGISTRY: dict[str, tuple[str, str]] = {}
 
     @staticmethod
     def register(name: str, module: str, class_name: str) -> None:

vllm/transformers_utils/tokenizers/mistral.py

@@ -257,7 +257,7 @@ class MistralTokenizer(TokenizerBase):
     # the following attributes are set to fit vLLM's design and are used
     # by the guided structured output backends.
     @property
-    def all_special_tokens_extended(self) -> List[str]:
+    def all_special_tokens_extended(self) -> list[str]:
         from mistral_common.tokens.tokenizers.base import SpecialTokens
 
         # tekken defines its own extended special tokens list
@@ -271,11 +271,11 @@ class MistralTokenizer(TokenizerBase):
         ]
 
     @property
-    def all_special_tokens(self) -> List[str]:
+    def all_special_tokens(self) -> list[str]:
         return self.all_special_tokens_extended
 
     @property
-    def all_special_ids(self) -> List[int]:
+    def all_special_ids(self) -> list[int]:
         return [
             self.all_special_tokens.index(t) for t in self.all_special_tokens
         ]
@@ -335,12 +335,12 @@ class MistralTokenizer(TokenizerBase):
             input_ids = self.encode_one(text, truncation, max_length)
         return Encoding(input_ids=input_ids)
 
-    def get_vocab(self) -> Dict[str, int]:
+    def get_vocab(self) -> dict[str, int]:
         # NB: the dictionary form of the vocabulary collapses token ids that map
         # to the same string but have different bytes
         return self._vocab_dict
 
-    def get_added_vocab(self) -> Dict[str, int]:
+    def get_added_vocab(self) -> dict[str, int]:
         # Mistral tokenizers have no added vocabulary
         return {}