[refactor] refactor needle.py.

This commit is contained in:
Zijie Tian
2026-01-03 18:33:48 +08:00
parent ff8b09cd35
commit 6927a75ac3
2 changed files with 176 additions and 145 deletions

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@@ -12,151 +12,7 @@ os.environ["NANOVLLM_LOG_LEVEL"] = "DEBUG"
import argparse
from nanovllm import LLM, SamplingParams
# ============================================================
# Needle Test Generator
# ============================================================
def generate_needle_prompt(
tokenizer,
target_length: int,
needle_position: float = 0.5,
needle_value: str = "7492",
use_chat_template: bool = True,
) -> tuple[str, str]:
"""
Generate a needle-in-haystack prompt of approximately target_length tokens.
Args:
tokenizer: HuggingFace tokenizer for length estimation
target_length: Target total sequence length in tokens
needle_position: Where to place needle (0.0=start, 0.5=middle, 1.0=end)
needle_value: The secret value to hide in the haystack
use_chat_template: Whether to use chat template for instruct models
Returns:
(prompt, expected_answer): The full prompt and the expected needle value
"""
# Haystack filler paragraphs (various topics to create realistic context)
haystack_paragraphs = [
"The weather today is quite pleasant with clear skies and moderate temperatures. "
"Many people are enjoying outdoor activities in the park. "
"Birds are singing in the trees and children are playing on the swings. ",
"In the world of technology, new innovations continue to emerge every day. "
"Researchers are working on advanced algorithms and computing systems. "
"The future of artificial intelligence looks promising with many breakthroughs. ",
"The history of human civilization spans thousands of years. "
"Ancient cultures developed writing, mathematics, and astronomy. "
"Trade routes connected distant lands and facilitated cultural exchange. ",
"Modern cooking combines traditional techniques with new ingredients. "
"Chefs around the world experiment with flavors and presentations. "
"Food brings people together and creates memorable experiences. ",
"The ocean covers more than seventy percent of Earth's surface. "
"Marine ecosystems support an incredible diversity of life forms. "
"Scientists continue to discover new species in the deep sea. ",
"Music has been a part of human culture since prehistoric times. "
"Different genres evolved across various regions and time periods. "
"Today, people can access millions of songs through digital platforms. ",
"Space exploration has revealed many secrets about our universe. "
"Telescopes can observe galaxies billions of light years away. "
"Future missions aim to establish human presence on other planets. ",
"The study of languages reveals patterns in human cognition. "
"Linguists analyze grammar, semantics, and phonetics across cultures. "
"Language continues to evolve with new words and expressions. ",
]
# The needle sentence
needle = f"The secret number you need to remember is {needle_value}. This is very important. "
# Question at the end
question = "\n\nQuestion: What is the secret number mentioned in the text above?\nAnswer: The secret number is"
# Estimate tokens for fixed parts
needle_tokens = len(tokenizer.encode(needle, add_special_tokens=False))
question_text = "What is the secret number mentioned in the text above? Answer with just the number."
question_tokens = len(tokenizer.encode(question_text, add_special_tokens=False))
# Buffer for chat template, special tokens, etc.
overhead_tokens = 100 if use_chat_template else 50
# Available tokens for haystack
haystack_target_tokens = target_length - needle_tokens - question_tokens - overhead_tokens
if haystack_target_tokens < 100:
raise ValueError(f"target_length {target_length} is too short for needle test")
# Build haystack by repeating paragraphs
haystack_parts = []
current_tokens = 0
para_idx = 0
while current_tokens < haystack_target_tokens:
para = haystack_paragraphs[para_idx % len(haystack_paragraphs)]
para_tokens = len(tokenizer.encode(para, add_special_tokens=False))
if current_tokens + para_tokens > haystack_target_tokens:
break
haystack_parts.append(para)
current_tokens += para_tokens
para_idx += 1
# Calculate needle insertion point
needle_idx = int(len(haystack_parts) * needle_position)
needle_idx = max(0, min(needle_idx, len(haystack_parts)))
# Insert needle
haystack_parts.insert(needle_idx, needle)
# Assemble prompt
full_text = "".join(haystack_parts)
if use_chat_template and hasattr(tokenizer, 'apply_chat_template'):
# Use chat template for instruct models
# For Qwen3, add /no_think to disable thinking mode
question_text = "/no_think Answer only with the secret number mentioned above, nothing else:"
messages = [
{"role": "user", "content": f"{full_text}\n\n{question_text}"}
]
prompt = tokenizer.apply_chat_template(
messages,
tokenize=False,
add_generation_prompt=True,
)
else:
# Raw text format for base models
question = "\n\nQuestion: What is the secret number mentioned in the text above?\nAnswer: The secret number is"
prompt = full_text + question
# Verify length
actual_tokens = len(tokenizer.encode(prompt, add_special_tokens=False))
print(f"[NeedleTest] Target: {target_length} tokens, Actual: {actual_tokens} tokens")
print(f"[NeedleTest] Needle position: {needle_position:.0%} ({needle_idx}/{len(haystack_parts)-1} paragraphs)")
print(f"[NeedleTest] Using chat template: {use_chat_template and hasattr(tokenizer, 'apply_chat_template')}")
return prompt, needle_value
def check_needle_answer(output_text: str, expected: str) -> bool:
"""Check if the model output contains the expected needle value."""
import re
# Clean output - remove special tokens and whitespace
output_clean = output_text.replace('<|im_end|>', '').replace('\r', ' ').replace('\n', ' ')
output_clean = ' '.join(output_clean.split()).lower()
expected_clean = expected.strip().lower()
# Check if expected value appears in output
# Also try to find it as a standalone number
if expected_clean in output_clean:
return True
# Try to extract numbers and check if expected is among them
numbers = re.findall(r'\d+', output_clean)
return expected_clean in numbers
from utils import generate_needle_prompt, check_needle_answer
# ============================================================

175
tests/utils.py Normal file
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@@ -0,0 +1,175 @@
"""
Test utilities for nano-vllm.
"""
import re
from typing import Tuple
# ============================================================
# Needle-in-Haystack Test Utilities
# ============================================================
# Haystack filler paragraphs (various topics to create realistic context)
HAYSTACK_PARAGRAPHS = [
"The weather today is quite pleasant with clear skies and moderate temperatures. "
"Many people are enjoying outdoor activities in the park. "
"Birds are singing in the trees and children are playing on the swings. ",
"In the world of technology, new innovations continue to emerge every day. "
"Researchers are working on advanced algorithms and computing systems. "
"The future of artificial intelligence looks promising with many breakthroughs. ",
"The history of human civilization spans thousands of years. "
"Ancient cultures developed writing, mathematics, and astronomy. "
"Trade routes connected distant lands and facilitated cultural exchange. ",
"Modern cooking combines traditional techniques with new ingredients. "
"Chefs around the world experiment with flavors and presentations. "
"Food brings people together and creates memorable experiences. ",
"The ocean covers more than seventy percent of Earth's surface. "
"Marine ecosystems support an incredible diversity of life forms. "
"Scientists continue to discover new species in the deep sea. ",
"Music has been a part of human culture since prehistoric times. "
"Different genres evolved across various regions and time periods. "
"Today, people can access millions of songs through digital platforms. ",
"Space exploration has revealed many secrets about our universe. "
"Telescopes can observe galaxies billions of light years away. "
"Future missions aim to establish human presence on other planets. ",
"The study of languages reveals patterns in human cognition. "
"Linguists analyze grammar, semantics, and phonetics across cultures. "
"Language continues to evolve with new words and expressions. ",
]
def generate_needle_prompt(
tokenizer,
target_length: int,
needle_position: float = 0.5,
needle_value: str = "7492",
use_chat_template: bool = True,
verbose: bool = True,
) -> Tuple[str, str]:
"""
Generate a needle-in-haystack prompt of approximately target_length tokens.
Args:
tokenizer: HuggingFace tokenizer for length estimation
target_length: Target total sequence length in tokens
needle_position: Where to place needle (0.0=start, 0.5=middle, 1.0=end)
needle_value: The secret value to hide in the haystack
use_chat_template: Whether to use chat template for instruct models
verbose: Whether to print generation info
Returns:
(prompt, expected_answer): The full prompt and the expected needle value
"""
# The needle sentence
needle = f"The secret number you need to remember is {needle_value}. This is very important. "
# Question at the end
question = "\n\nQuestion: What is the secret number mentioned in the text above?\nAnswer: The secret number is"
# Estimate tokens for fixed parts
needle_tokens = len(tokenizer.encode(needle, add_special_tokens=False))
question_text = "What is the secret number mentioned in the text above? Answer with just the number."
question_tokens = len(tokenizer.encode(question_text, add_special_tokens=False))
# Buffer for chat template, special tokens, etc.
overhead_tokens = 100 if use_chat_template else 50
# Available tokens for haystack
haystack_target_tokens = target_length - needle_tokens - question_tokens - overhead_tokens
if haystack_target_tokens < 100:
raise ValueError(f"target_length {target_length} is too short for needle test")
# Build haystack by repeating paragraphs
haystack_parts = []
current_tokens = 0
para_idx = 0
while current_tokens < haystack_target_tokens:
para = HAYSTACK_PARAGRAPHS[para_idx % len(HAYSTACK_PARAGRAPHS)]
para_tokens = len(tokenizer.encode(para, add_special_tokens=False))
if current_tokens + para_tokens > haystack_target_tokens:
break
haystack_parts.append(para)
current_tokens += para_tokens
para_idx += 1
# Calculate needle insertion point
needle_idx = int(len(haystack_parts) * needle_position)
needle_idx = max(0, min(needle_idx, len(haystack_parts)))
# Insert needle
haystack_parts.insert(needle_idx, needle)
# Assemble prompt
full_text = "".join(haystack_parts)
if use_chat_template and hasattr(tokenizer, 'apply_chat_template'):
# Use chat template for instruct models
# For Qwen3, add /no_think to disable thinking mode
question_text = "/no_think Answer only with the secret number mentioned above, nothing else:"
messages = [
{"role": "user", "content": f"{full_text}\n\n{question_text}"}
]
prompt = tokenizer.apply_chat_template(
messages,
tokenize=False,
add_generation_prompt=True,
)
else:
# Raw text format for base models
question = "\n\nQuestion: What is the secret number mentioned in the text above?\nAnswer: The secret number is"
prompt = full_text + question
# Verify length
actual_tokens = len(tokenizer.encode(prompt, add_special_tokens=False))
if verbose:
print(f"[NeedleTest] Target: {target_length} tokens, Actual: {actual_tokens} tokens")
print(f"[NeedleTest] Needle position: {needle_position:.0%} ({needle_idx}/{len(haystack_parts)-1} paragraphs)")
print(f"[NeedleTest] Using chat template: {use_chat_template and hasattr(tokenizer, 'apply_chat_template')}")
return prompt, needle_value
def check_needle_answer(output_text: str, expected: str) -> bool:
"""Check if the model output contains the expected needle value."""
# Clean output - remove special tokens and whitespace
output_clean = output_text.replace('<|im_end|>', '').replace('\r', ' ').replace('\n', ' ')
output_clean = ' '.join(output_clean.split()).lower()
expected_clean = expected.strip().lower()
# Check if expected value appears in output
# Also try to find it as a standalone number
if expected_clean in output_clean:
return True
# Try to extract numbers and check if expected is among them
numbers = re.findall(r'\d+', output_clean)
return expected_clean in numbers
def generate_random_token_ids(
length: int,
vocab_size: int = 10000,
seed: int = 42,
) -> list:
"""
Generate random token IDs for testing.
Args:
length: Number of tokens to generate
vocab_size: Maximum token ID (exclusive)
seed: Random seed for reproducibility
Returns:
List of random token IDs
"""
from random import randint, seed as set_seed
set_seed(seed)
return [randint(0, vocab_size - 1) for _ in range(length)]