Files
sglang/test/registered/sampling/test_sampling_mask.py
T

254 lines
9.0 KiB
Python

import math
import unittest
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=240, stage="base-b", runner_config="1-gpu-small")
register_amd_ci(est_time=320, suite="stage-b-test-1-gpu-small-amd")
_MAX_NEW_TOKENS = 4
_TOP_P = 0.99
_TOP_K = 10
_SAMPLING_SEED = 1234
_SERVER_ARGS = (
"--mem-fraction-static",
"0.7",
)
_INVALID_SAMPLING_MASK_ERROR = (
"top_p-only sampling is valid but can return huge masks in the tail"
)
class SamplingMaskTestMixin:
@classmethod
def _launch_server(cls, other_args=()):
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,
other_args=(*_SERVER_ARGS, *other_args),
)
@classmethod
def tearDownClass(cls):
kill_process_tree(cls.process.pid)
def _post_generate(
self,
sampling_params,
return_sampling_mask=True,
return_logprob=False,
top_logprobs_num=0,
):
payload = {
"text": "The capital of France is",
"sampling_params": sampling_params,
"return_sampling_mask": return_sampling_mask,
}
if return_logprob:
payload["return_logprob"] = True
payload["top_logprobs_num"] = top_logprobs_num
return requests.post(self.base_url + "/generate", json=payload, timeout=60)
def _generate_sampling_masks(self, sampling_params):
response = self._post_generate(sampling_params)
self.assertEqual(response.status_code, 200, response.text)
output = response.json()
meta_info = output["meta_info"]
output_ids = output["output_ids"]
sampling_masks = meta_info["output_token_sampling_mask"]
self.assertEqual(len(output_ids), _MAX_NEW_TOKENS)
self.assertEqual(meta_info["completion_tokens"], len(output_ids))
self.assertEqual(
meta_info["output_token_sampling_mask_length"], len(output_ids)
)
self.assertEqual(len(sampling_masks), len(output_ids))
for output_id, sampling_mask in zip(output_ids, sampling_masks):
self.assertIn(output_id, sampling_mask)
return sampling_masks
def _assert_rejects_unbounded_sampling_mask(self, sampling_params):
response = self._post_generate(sampling_params)
self.assertEqual(response.status_code, 400, response.text)
self.assertIn(_INVALID_SAMPLING_MASK_ERROR, response.text)
class TestSamplingMask(SamplingMaskTestMixin, CustomTestCase):
@classmethod
def setUpClass(cls):
cls._launch_server()
def test_generate_returns_sampling_mask(self):
top_p_sampling_masks = self._generate_sampling_masks(
{
"temperature": 1.0,
"top_k": _TOP_K,
"top_p": _TOP_P,
"max_new_tokens": _MAX_NEW_TOKENS,
"ignore_eos": True,
}
)
# The mask keeps at most top_k tokens, plus possibly the actually
# sampled token when the sampling kernel picks one just outside the
# mask's topk reconstruction (fp cumsum divergence); see
# Sampler._attach_sampling_mask_to_output.
for sampling_mask in top_p_sampling_masks:
self.assertLessEqual(len(sampling_mask), _TOP_K + 1)
top_k_sampling_masks = self._generate_sampling_masks(
{
"temperature": 1.0,
"top_k": _TOP_K,
"max_new_tokens": _MAX_NEW_TOKENS,
"ignore_eos": True,
}
)
for sampling_mask in top_k_sampling_masks:
self.assertIn(len(sampling_mask), (_TOP_K, _TOP_K + 1))
top_k_top_p_one_sampling_masks = self._generate_sampling_masks(
{
"temperature": 1.0,
"top_k": _TOP_K,
"top_p": 1.0,
"max_new_tokens": _MAX_NEW_TOKENS,
"ignore_eos": True,
}
)
for sampling_mask in top_k_top_p_one_sampling_masks:
self.assertIn(len(sampling_mask), (_TOP_K, _TOP_K + 1))
def test_sampling_mask_matches_topk_logprobs(self):
"""Check the returned mask and its renormalized logprobs.
We get the per-token full-vocab logprobs via ``return_logprob`` with
``top_logprobs_num == top_k``, which covers every token the mask can
contain. With ``temperature=1.0`` these are the sampler's distribution,
so ``p = exp(logprob)`` are the exact probabilities. For each token, we check:
1. the returned mask matches the nucleus reconstructed from those probs,
2. sampling_logprob == log(p[sampled] / sum(p[t] for t in mask)).
"""
top_k, top_p = _TOP_K, _TOP_P
response = self._post_generate(
{
"temperature": 1.0,
"top_k": top_k,
"top_p": top_p,
"max_new_tokens": _MAX_NEW_TOKENS,
"ignore_eos": True,
},
return_logprob=True,
top_logprobs_num=top_k,
)
self.assertEqual(response.status_code, 200, response.text)
output = response.json()
meta_info = output["meta_info"]
output_ids = output["output_ids"]
sampling_masks = meta_info["output_token_sampling_mask"]
sampling_logprobs = meta_info["output_token_sampling_logprobs"]
top_logprobs = meta_info["output_top_logprobs"] # [logprob, id, text] per token
self.assertEqual(len(sampling_masks), len(output_ids))
self.assertEqual(len(sampling_logprobs), len(output_ids))
self.assertEqual(len(top_logprobs), len(output_ids))
for output_id, mask, mask_logprob, step_top_logprobs in zip(
output_ids, sampling_masks, sampling_logprobs, top_logprobs
):
probs = {
int(tid): math.exp(logprob) for logprob, tid, _ in step_top_logprobs
}
reconstructed = []
mass_before = 0.0
for logprob, tid, _ in step_top_logprobs:
if mass_before <= top_p:
reconstructed.append(int(tid))
mass_before += math.exp(logprob)
if output_id not in reconstructed:
reconstructed.append(output_id)
# ``<= 1``: fp32 (server) and fp64 (here) cumsums may split on the
# single token straddling the top_p cut.
self.assertLessEqual(len(set(mask) ^ set(reconstructed)), 1)
support_mass = sum(probs[tid] for tid in mask)
expected_logprob = math.log(probs[output_id] / support_mass)
self.assertAlmostEqual(mask_logprob, expected_logprob, delta=1e-2)
def test_generate_rejects_unbounded_sampling_mask(self):
self._assert_rejects_unbounded_sampling_mask(
{
"temperature": 1.0,
"top_p": _TOP_P,
"max_new_tokens": _MAX_NEW_TOKENS,
"ignore_eos": True,
}
)
self._assert_rejects_unbounded_sampling_mask(
{
"temperature": 1.0,
"top_p": 1.0,
"max_new_tokens": _MAX_NEW_TOKENS,
"ignore_eos": True,
}
)
class TestSamplingMaskDeterministic(SamplingMaskTestMixin, CustomTestCase):
@classmethod
def setUpClass(cls):
# This test validates sampler/output determinism, not backend selection.
# Pin Triton so the same deterministic path runs on CUDA and ROCm CI.
cls._launch_server(
("--enable-deterministic-inference", "--attention-backend", "triton")
)
def test_return_sampling_mask_preserves_deterministic_sampling(self):
sampling_params = {
"temperature": 1.0,
"top_k": _TOP_K,
"top_p": 1.0,
"sampling_seed": _SAMPLING_SEED,
"max_new_tokens": _MAX_NEW_TOKENS,
"ignore_eos": True,
}
with_mask_response = self._post_generate(
sampling_params, return_sampling_mask=True
)
self.assertEqual(with_mask_response.status_code, 200, with_mask_response.text)
without_mask_response = self._post_generate(
sampling_params, return_sampling_mask=False
)
self.assertEqual(
without_mask_response.status_code, 200, without_mask_response.text
)
with_mask_output = with_mask_response.json()
without_mask_output = without_mask_response.json()
self.assertEqual(
with_mask_output["output_ids"], without_mask_output["output_ids"]
)
self.assertEqual(with_mask_output["text"], without_mask_output["text"])
if __name__ == "__main__":
unittest.main()