Files
sglang/test/registered/sampling/test_penalty.py
2026-02-12 21:08:37 +08:00

263 lines
9.7 KiB
Python

import json
import random
import re
import unittest
from concurrent.futures import ThreadPoolExecutor
import requests
from sglang.srt.utils import kill_process_tree
from sglang.test.ci.ci_register import register_amd_ci, register_cuda_ci
from sglang.test.test_utils import (
DEFAULT_SMALL_MODEL_NAME_FOR_TEST,
DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
DEFAULT_URL_FOR_TEST,
CustomTestCase,
popen_launch_server,
)
register_cuda_ci(est_time=82, suite="stage-b-test-small-1-gpu")
register_amd_ci(est_time=82, suite="stage-b-test-small-1-gpu-amd")
class TestPenalty(CustomTestCase):
@classmethod
def setUpClass(cls):
cls.model = DEFAULT_SMALL_MODEL_NAME_FOR_TEST
cls.base_url = DEFAULT_URL_FOR_TEST
cls.process = popen_launch_server(
cls.model,
cls.base_url,
timeout=DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
)
@classmethod
def tearDownClass(cls):
kill_process_tree(cls.process.pid)
def run_decode(self, sampling_params):
"""Helper method for basic decode tests."""
return_logprob = True
top_logprobs_num = 5
return_text = True
n = 1
response = requests.post(
self.base_url + "/generate",
json={
# prompt that is supposed to generate < 32 tokens
"text": "<|start_header_id|>user<|end_header_id|>\n\nWhat is the answer for 1 + 1 = ?<|eot_id|><|start_header_id|>assistant<|end_header_id|>\n\n",
"sampling_params": {
"max_new_tokens": 48,
"n": n,
**sampling_params,
},
"return_logprob": return_logprob,
"top_logprobs_num": top_logprobs_num,
"return_text_in_logprobs": return_text,
"logprob_start_len": 0,
},
)
self.assertEqual(response.status_code, 200)
print(json.dumps(response.json()))
print("=" * 100)
def run_generate_with_prompt(
self, prompt, sampling_params, max_tokens=100, seed=None
):
"""Helper method to generate text with a specific prompt and parameters."""
sampling_params = sampling_params.copy()
sampling_params.setdefault("temperature", 0.05)
sampling_params.setdefault("top_p", 1.0)
if seed is not None:
sampling_params["seed"] = seed
response = requests.post(
self.base_url + "/v1/chat/completions",
json={
"model": self.model,
"messages": [{"role": "user", "content": prompt}],
"max_tokens": max_tokens,
**sampling_params,
},
)
self.assertEqual(response.status_code, 200)
result = response.json()
content = result["choices"][0]["message"]["content"]
return content
def _get_vocab_diversity(self, text):
"""Calculate vocabulary diversity as unique_words / total_words.
Higher values mean more diverse (less repetitive) text.
"""
words = re.findall(r"\b\w+\b", text.lower())
if not words:
return 1.0
return len(set(words)) / len(words)
def _test_penalty_effect(
self,
prompt,
baseline_params,
penalty_params,
expected_reduction=True,
max_tokens=150,
):
"""Generic test for penalty effects using vocabulary diversity.
Measures unique_words/total_words ratio instead of counting a specific
word, because penalties affect ALL token probabilities — the model may
avoid some repeated tokens while using others more.
"""
# Use higher temperature so penalties can actually affect token selection.
# The default temperature (0.05) is near-greedy, making penalty adjustments
# to logits ineffective since the top token still dominates.
baseline_params = baseline_params.copy()
penalty_params = penalty_params.copy()
baseline_params.setdefault("temperature", 0.8)
penalty_params.setdefault("temperature", 0.8)
# Run multiple iterations to get more reliable results
# Use fixed seeds for deterministic behavior
base_seed = 42
baseline_diversities = []
penalty_diversities = []
for i in range(5):
seed = base_seed + i
baseline_output = self.run_generate_with_prompt(
prompt, baseline_params, max_tokens, seed=seed
)
penalty_output = self.run_generate_with_prompt(
prompt, penalty_params, max_tokens, seed=seed
)
baseline_diversities.append(self._get_vocab_diversity(baseline_output))
penalty_diversities.append(self._get_vocab_diversity(penalty_output))
avg_baseline = sum(baseline_diversities) / len(baseline_diversities)
avg_penalty = sum(penalty_diversities) / len(penalty_diversities)
if expected_reduction:
# Penalty should increase vocabulary diversity (less repetition)
self.assertGreater(
avg_penalty,
avg_baseline,
f"Penalty should increase vocab diversity: {avg_baseline:.3f}{avg_penalty:.3f}",
)
else:
# Negative penalty should decrease diversity (more repetition)
self.assertLess(
avg_penalty,
avg_baseline,
f"Negative penalty should decrease vocab diversity: {avg_baseline:.3f}{avg_penalty:.3f}",
)
def test_default_values(self):
self.run_decode({})
def test_frequency_penalty(self):
self.run_decode({"frequency_penalty": 2})
def test_min_new_tokens(self):
self.run_decode({"min_new_tokens": 16})
def test_presence_penalty(self):
self.run_decode({"presence_penalty": 2})
def test_penalty_mixed(self):
args = [
{},
{},
{},
{"frequency_penalty": 2},
{"presence_penalty": 1},
{"min_new_tokens": 16},
{"frequency_penalty": 0.2},
{"presence_penalty": 0.4},
{"min_new_tokens": 8},
{"frequency_penalty": 0.4, "presence_penalty": 0.8},
{"frequency_penalty": 0.4, "min_new_tokens": 12},
{"presence_penalty": 0.8, "min_new_tokens": 12},
{"presence_penalty": -0.3, "frequency_penalty": 1.3, "min_new_tokens": 32},
{"presence_penalty": 0.3, "frequency_penalty": -1.3, "min_new_tokens": 32},
]
random.shuffle(args * 5)
with ThreadPoolExecutor(8) as executor:
list(executor.map(self.run_decode, args))
def test_frequency_penalty_reduces_word_repetition(self):
"""Test that frequency penalty increases vocabulary diversity."""
prompt = "Write exactly 10 very small sentences, each containing the word 'data'. Use the word 'data' as much as possible."
baseline_params = {"frequency_penalty": 0.0, "repetition_penalty": 1.0}
penalty_params = {"frequency_penalty": 1.99, "repetition_penalty": 1.0}
self._test_penalty_effect(prompt, baseline_params, penalty_params)
def test_presence_penalty_reduces_topic_repetition(self):
"""Test that presence penalty increases vocabulary diversity."""
prompt = "Write the word 'machine learning' exactly 20 times in a row, separated by spaces."
baseline_params = {"presence_penalty": 0.0, "repetition_penalty": 1.0}
penalty_params = {"presence_penalty": 1.99, "repetition_penalty": 1.0}
self._test_penalty_effect(prompt, baseline_params, penalty_params)
def test_combined_penalties_reduce_repetition(self):
"""Test that combined penalties increase vocabulary diversity."""
prompt = "Write exactly 10 short sentences, each containing the word 'data'. Use the word 'data' as much as possible."
baseline_params = {
"frequency_penalty": 0.0,
"presence_penalty": 0.0,
"repetition_penalty": 1.0,
}
penalty_params = {
"frequency_penalty": 1.99,
"presence_penalty": 1.99,
"repetition_penalty": 1.99,
}
self._test_penalty_effect(prompt, baseline_params, penalty_params)
def test_penalty_edge_cases_negative_penalty_values(self):
"""Test that negative penalties decrease vocabulary diversity."""
prompt = "Write the word 'test' exactly 15 times in a row, separated by spaces."
baseline_params = {
"frequency_penalty": 0.0,
"presence_penalty": 0.0,
"repetition_penalty": 1.0,
}
negative_penalty_params = {
"frequency_penalty": -0.5,
"presence_penalty": -0.25,
"repetition_penalty": 1.0,
}
self._test_penalty_effect(
prompt,
baseline_params,
negative_penalty_params,
expected_reduction=False,
)
def test_penalty_edge_cases_extreme_penalty_values(self):
"""Test that extreme penalties strongly increase vocabulary diversity."""
prompt = (
"Write the word 'extreme' exactly 20 times in a row, separated by spaces."
)
baseline_params = {
"frequency_penalty": 0.0,
"presence_penalty": 0.0,
"repetition_penalty": 1.0,
}
extreme_penalty_params = {
"frequency_penalty": 2.0,
"presence_penalty": 2.0,
"repetition_penalty": 2.0,
}
self._test_penalty_effect(
prompt,
baseline_params,
extreme_penalty_params,
)
if __name__ == "__main__":
unittest.main(verbosity=3)