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Merge pull request #787 from duc-phamh/improve_message_trimming

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Improve message trimming
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Ishaan Jaff 2023-11-11 09:39:43 -08:00 • committed by GitHub
commit fd6064b571
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2 changed files with 112 additions and 14 deletions
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litellm/utils.py
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@ -19,6 +19,7 @@ import uuid
import aiohttp
import logging
import asyncio
import copy
from tokenizers import Tokenizer
from dataclasses import (
dataclass,
@ -1111,6 +1112,50 @@ def decode(model: str, tokens: List[int]):
dec = tokenizer_json["tokenizer"].decode(tokens)
return dec
def openai_token_counter(messages, model="gpt-3.5-turbo-0613"):
"""
Return the number of tokens used by a list of messages.
Borrowed from https://github.com/openai/openai-cookbook/blob/main/examples/How_to_count_tokens_with_tiktoken.ipynb.
"""
try:
encoding = tiktoken.encoding_for_model(model)
except KeyError:
print("Warning: model not found. Using cl100k_base encoding.")
encoding = tiktoken.get_encoding("cl100k_base")
if model in {
"gpt-3.5-turbo-0613",
"gpt-3.5-turbo-16k-0613",
"gpt-4-0314",
"gpt-4-32k-0314",
"gpt-4-0613",
"gpt-4-32k-0613",
}:
tokens_per_message = 3
tokens_per_name = 1
elif model == "gpt-3.5-turbo-0301":
tokens_per_message = 4 # every message follows <|start|>{role/name}\n{content}<|end|>\n
tokens_per_name = -1 # if there's a name, the role is omitted
elif "gpt-3.5-turbo" in model:
print("Warning: gpt-3.5-turbo may update over time. Returning num tokens assuming gpt-3.5-turbo-0613.")
return openai_token_counter(messages, model="gpt-3.5-turbo-0613")
elif "gpt-4" in model:
print("Warning: gpt-4 may update over time. Returning num tokens assuming gpt-4-0613.")
return openai_token_counter(messages, model="gpt-4-0613")
else:
raise NotImplementedError(
f"""num_tokens_from_messages() is not implemented for model {model}. See https://github.com/openai/openai-python/blob/main/chatml.md for information on how messages are converted to tokens."""
)
num_tokens = 0
for message in messages:
num_tokens += tokens_per_message
for key, value in message.items():
num_tokens += len(encoding.encode(value))
if key == "name":
num_tokens += tokens_per_name
num_tokens += 3 # every reply is primed with <|start|>assistant<|message|>
return num_tokens
def token_counter(model="", text=None, messages: Optional[List] = None):
"""
Count the number of tokens in a given text using a specified model.
@ -1131,14 +1176,17 @@ def token_counter(model="", text=None, messages: Optional[List] = None):
raise ValueError("text and messages cannot both be None")
num_tokens = 0
if model is not None:
if model is not None:
tokenizer_json = _select_tokenizer(model=model)
if tokenizer_json["type"] == "huggingface_tokenizer":
enc = tokenizer_json["tokenizer"].encode(text)
num_tokens = len(enc.ids)
elif tokenizer_json["type"] == "openai_tokenizer":
enc = tokenizer_json["tokenizer"].encode(text)
num_tokens = len(enc)
if messages is not None:
num_tokens = openai_token_counter(messages, model=model)
else:
enc = tokenizer_json["tokenizer"].encode(text)
num_tokens = len(enc)
else:
num_tokens = len(encoding.encode(text))
return num_tokens
@ -4574,13 +4622,13 @@ def completion_with_fallbacks(**kwargs):
def process_system_message(system_message, max_tokens, model):
system_message_event = {"role": "system", "content": system_message}
system_message_tokens = get_token_count(system_message_event, model)
system_message_tokens = get_token_count([system_message_event], model)
if system_message_tokens > max_tokens:
print_verbose("`tokentrimmer`: Warning, system message exceeds token limit. Trimming...")
# shorten system message to fit within max_tokens
new_system_message = shorten_message_to_fit_limit(system_message_event, max_tokens, model)
system_message_tokens = get_token_count(new_system_message, model)
system_message_tokens = get_token_count([new_system_message], model)
return system_message_event, max_tokens - system_message_tokens
@ -4590,11 +4638,15 @@ def process_messages(messages, max_tokens, model):
final_messages = []
for message in messages:
final_messages = attempt_message_addition(final_messages, message, max_tokens, model)
used_tokens = get_token_count(final_messages, model)
available_tokens = max_tokens - used_tokens
if available_tokens <= 3:
break
final_messages = attempt_message_addition(final_messages=final_messages, message=message, available_tokens=available_tokens, max_tokens=max_tokens, model=model)
return final_messages
def attempt_message_addition(final_messages, message, max_tokens, model):
def attempt_message_addition(final_messages, message, available_tokens, max_tokens, model):
temp_messages = [message] + final_messages
temp_message_tokens = get_token_count(messages=temp_messages, model=model)
@ -4604,7 +4656,7 @@ def attempt_message_addition(final_messages, message, max_tokens, model):
# if temp_message_tokens > max_tokens, try shortening temp_messages
elif "function_call" not in message:
# fit updated_message to be within temp_message_tokens - max_tokens (aka the amount temp_message_tokens is greate than max_tokens)
updated_message = shorten_message_to_fit_limit(message, temp_message_tokens - max_tokens, model)
updated_message = shorten_message_to_fit_limit(message, available_tokens, model)
if can_add_message(updated_message, final_messages, max_tokens, model):
return [updated_message] + final_messages
@ -4626,6 +4678,13 @@ def shorten_message_to_fit_limit(
"""
Shorten a message to fit within a token limit by removing characters from the middle.
"""
# For OpenAI models, even blank messages cost 7 token,
# and if the buffer is less than 3, the while loop will never end,
# hence the value 10.
if 'gpt' in model and tokens_needed <= 10:
return message
content = message["content"]
while True:
@ -4674,6 +4733,7 @@ def trim_messages(
"""
# Initialize max_tokens
# if users pass in max tokens, trim to this amount
messages = copy.deepcopy(messages)
try:
print_verbose(f"trimming messages")
if max_tokens == None:
@ -4690,6 +4750,7 @@ def trim_messages(
system_message = ""
for message in messages:
if message["role"] == "system":
system_message += '\n' if system_message else ''
system_message += message["content"]
current_tokens = token_counter(model=model, messages=messages)
@ -4703,14 +4764,23 @@ def trim_messages(
print_verbose(f"Need to trim input messages: {messages}, current_tokens{current_tokens}, max_tokens: {max_tokens}")
if system_message:
system_message_event, max_tokens = process_system_message(system_message=system_message, max_tokens=max_tokens, model=model)
messages = messages + [system_message_event]
if max_tokens == 0: # the system messages are too long
return [system_message_event]
# Since all system messages are combined and trimmed to fit the max_tokens,
# we remove all system messages from the messages list
messages = [message for message in messages if message["role"] != "system"]
final_messages = process_messages(messages=messages, max_tokens=max_tokens, model=model)
# Add system message to the beginning of the final messages
if system_message:
final_messages = [system_message_event] + final_messages
if return_response_tokens: # if user wants token count with new trimmed messages
response_tokens = max_tokens - get_token_count(final_messages, model)
return final_messages, response_tokens
return final_messages
except Exception as e: # [NON-Blocking, if error occurs just return final_messages
print_verbose(f"Got exception while token trimming{e}")