Add Logprobs unit test with a loose threshold (#10230)

Co-authored-by: Yusheng Su <yushengsu.thu@gmail.com>
Co-authored-by: Chayenne <zhaochen20@outlook.com>
Co-authored-by: Ryan <ryan@ryanmini.mynetworksettings.com>

test/srt/run_suite.py

@@ -81,6 +81,7 @@ suites = {
         TestFile("test_input_embeddings.py", 38),
         TestFile("test_io_struct.py", 8),
         TestFile("test_jinja_template_utils.py", 1),
+        TestFile("test_logprobs.py", 55),
         TestFile("test_metrics.py", 32),
         TestFile("test_metrics_utils.py", 1),
         TestFile("test_mla.py", 167),

test/srt/test_logprobs.py

+import io
+import os
+import pickle
+import random
+import time
+import unittest
+
+import numpy as np
+import requests
+import torch
+
+import sglang as sgl
+from sglang.test.test_utils import (
+    DEFAULT_SMALL_MODEL_NAME_FOR_TEST,
+    write_github_step_summary,
+)
+
+# Dense model configuration
+DENSE_MODEL_NAME = DEFAULT_SMALL_MODEL_NAME_FOR_TEST
+if torch.version.hip is not None:
+    print("Running on AMD ROCm GPU")
+    DENSE_INPUT_PKL_URL = "https://huggingface.co/datasets/yushengsu/logprobs/resolve/main/sglang_baseline_2000_amd.pkl"
+    DENSE_TOLERANCE_MAX_DIFF = 1.4
+    DENSE_TOLERANCE_MEAN_DIFF = 0.1
+elif torch.version.cuda is not None:
+    print("Running on NVIDIA CUDA GPU")
+    DENSE_INPUT_PKL_URL = "https://huggingface.co/datasets/font-info/logprobs/resolve/main/sglang_baseline_2000.pkl"
+    DENSE_TOLERANCE_MAX_DIFF = 1.5
+    DENSE_TOLERANCE_MEAN_DIFF = 0.1
+else:
+    print("No GPU backend (CPU only)")
+
+# Common configuration
+TOP_K = 20
+MAX_RETRIES = 3
+RETRY_DELAY = 2
+NUM_SAMPLES = 1000
+LOGPROB_SAMPLE_RATIO = 0.5
+TEMPERATURE = 1.0
+
+
+class TestLogprobsDense(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        """Set up the test class - initialize the engine once for all tests."""
+        print(f"Launching SGLang Engine with {DENSE_MODEL_NAME}...")
+        cls.engine = sgl.Engine(
+            model_path=DENSE_MODEL_NAME,
+            random_seed=42,
+            skip_tokenizer_init=True,
+            mem_fraction_static=0.85,
+        )
+
+    @classmethod
+    def tearDownClass(cls):
+        """Clean up after all tests - shutdown the engine."""
+        cls.engine.shutdown()
+        torch.cuda.empty_cache()
+
+    def load_test_data(self):
+        """Load test data from Hugging Face dataset with retry mechanism."""
+        print(f"Loading data from {DENSE_INPUT_PKL_URL}...")
+
+        for attempt in range(MAX_RETRIES):
+            try:
+                response = requests.get(DENSE_INPUT_PKL_URL, timeout=30)
+                response.raise_for_status()
+
+                with io.BytesIO(response.content) as f:
+                    records = pickle.load(f)
+
+                if not records:
+                    raise ValueError("Empty dataset")
+
+                print(f"Successfully loaded {len(records)} records")
+                return records
+
+            except Exception as e:
+                print(f"Attempt {attempt + 1}/{MAX_RETRIES} failed: {e}")
+                if attempt == MAX_RETRIES - 1:
+                    raise Exception(
+                        f"Failed to load data after {MAX_RETRIES} attempts: {e}"
+                    )
+                time.sleep(RETRY_DELAY)
+
+    def compare_meta(self, baseline_meta, sglang_meta):
+        """Compare metadata between two outputs and return max and mean differences."""
+        diffs = []
+        for key in ["input_top_logprobs", "output_top_logprobs"]:
+            baseline_logprobs, sglang_logprobs = baseline_meta[key], sglang_meta[key]
+            self.assertEqual(
+                len(baseline_logprobs),
+                len(sglang_logprobs),
+                f"Length of {key} is not equal, sglang did not return the correct number of log probs(should be top 20)",
+            )
+            for baseline_entry, sglang_entry in zip(baseline_logprobs, sglang_logprobs):
+                if not baseline_entry or not sglang_entry:
+                    continue
+                baseline_token_map = {tid: lp for lp, tid, _ in baseline_entry}
+                sglang_token_map = {tid: lp for lp, tid, _ in sglang_entry}
+                common_tokens = baseline_token_map.keys() & sglang_token_map.keys()
+                self.assertGreaterEqual(
+                    len(common_tokens),
+                    TOP_K / 2,
+                    f"there are only {len(common_tokens)} common topk tokens that matches",
+                )
+                for token_id in common_tokens:
+                    diffs.append(
+                        abs(baseline_token_map[token_id] - sglang_token_map[token_id])
+                    )
+        return max(diffs), float(np.mean(diffs))
+
+    def test_logprobs_comparison(self):
+        """Test the logprobs comparison functionality with different parameter combinations."""
+        # Load test data with retry mechanism
+        records = self.load_test_data()
+
+        with self.subTest(
+            config={
+                "num_samples": NUM_SAMPLES,
+                "logprob_sample_ratio": LOGPROB_SAMPLE_RATIO,
+                "temperature": TEMPERATURE,
+            }
+        ):
+
+            # Sample records for this config
+            test_records = random.sample(records, k=min(NUM_SAMPLES, len(records)))
+            random.shuffle(test_records)
+
+            # Calculate how many samples should return logprobs
+            logprob_count = int(len(test_records) * LOGPROB_SAMPLE_RATIO)
+            print(
+                f"Testing with {len(test_records)} samples, temperature={TEMPERATURE}"
+            )
+            print(
+                f"Will return logprobs for {logprob_count} samples (ratio: {LOGPROB_SAMPLE_RATIO})"
+            )
+
+            all_max, all_mean = [], []
+            logprob_returned_count = 0
+
+            # Process all records at once
+            input_ids = [rec["ids"] for rec in test_records]
+            logprob_start_lens = [rec["start_pos"] for rec in test_records]
+
+            # Determine which samples should return logprobs (randomly selected)
+            logprob_indices = set(
+                random.sample(range(len(test_records)), logprob_count)
+            )
+            return_logprob_array = [
+                sample_idx in logprob_indices for sample_idx in range(len(test_records))
+            ]
+
+            # Sampling param per request
+            sampling_params = [
+                {
+                    "temperature": TEMPERATURE,
+                    "top_p": 1.0,
+                    "top_k": TOP_K,
+                    "max_new_tokens": 1,
+                }
+                for _ in test_records
+            ]
+
+            outputs = self.engine.generate(
+                input_ids=input_ids,
+                sampling_params=sampling_params,
+                return_logprob=return_logprob_array,
+                logprob_start_len=logprob_start_lens,
+                top_logprobs_num=TOP_K,
+            )
+
+            for sample_idx, (rec, output) in enumerate(zip(test_records, outputs)):
+                # Only compare logprobs for samples that should have them
+                if sample_idx in logprob_indices:
+                    # Safe access to meta_info and input_top_logprobs
+                    meta_info = output.get("meta_info")
+                    input_top_logprobs = (
+                        meta_info.get("input_top_logprobs") if meta_info else None
+                    )
+
+                    self.assertIsNotNone(
+                        input_top_logprobs,
+                        f"return_logprob enabled on this sample, but input_top_logprobs is None (length: {len(input_top_logprobs) if input_top_logprobs is not None else 'N/A'})",
+                    )
+                    baseline_meta = rec["meta"]
+                    sglang_meta = meta_info
+
+                    max_diff, mean_diff = self.compare_meta(baseline_meta, sglang_meta)
+                    all_max.append(max_diff)
+                    all_mean.append(mean_diff)
+                    logprob_returned_count += 1
+                else:
+                    # Verify that logprobs were not returned for this sample
+                    meta_info = output.get("meta_info")
+                    input_top_logprobs = (
+                        meta_info.get("input_top_logprobs") if meta_info else None
+                    )
+                    output_token_ids_logprobs = (
+                        meta_info.get("output_token_ids_logprobs")
+                        if meta_info
+                        else None
+                    )
+
+                    self.assertFalse(
+                        input_top_logprobs,
+                        f"return_logprob is disabled on this sample, Sample {sample_idx} should not have logprobs, content: {output_token_ids_logprobs}",
+                    )
+
+            max_of_max = max(all_max) if all_max else 0.0
+            mean_of_mean = np.mean(all_mean) if all_mean else 0.0
+
+            print(f"max Δ={max_of_max:.6g}")
+            print(f"mean Δ={mean_of_mean:.6g}")
+            print(
+                f"logprobs returned for {logprob_returned_count} samples (expected: {logprob_count})"
+            )
+
+            # Verify correct number of logprobs returned
+            self.assertEqual(
+                logprob_returned_count,
+                logprob_count,
+                f"Expected {logprob_count} samples with logprobs, got {logprob_returned_count}",
+            )
+
+            # Write results to GitHub summary
+            summary_content = f"""
+- **Configuration**: {{"num_samples": {NUM_SAMPLES}, "logprob_sample_ratio": {LOGPROB_SAMPLE_RATIO}, "temperature": {TEMPERATURE}}}
+- **Max of max Δ**: {max_of_max:.6g}
+- **Mean of mean Δ**: {mean_of_mean:.6g}
+- **Status**: {'✅ Passed' if max_of_max <= DENSE_TOLERANCE_MAX_DIFF and mean_of_mean <= DENSE_TOLERANCE_MEAN_DIFF else '❌ Failed'}
+"""
+            write_github_step_summary(summary_content)
+
+            # Basic validation
+            self.assertIsInstance(all_max, list)
+            self.assertIsInstance(all_mean, list)
+            self.assertGreater(
+                len(all_max),
+                0,
+                f"No test samples processed for config {{'num_samples': {NUM_SAMPLES}, 'logprob_sample_ratio': {LOGPROB_SAMPLE_RATIO}, 'temperature': {TEMPERATURE}}}",
+            )
+
+            # Tolerance checks with clear error messages
+            failed_samples = []
+            for sample_idx, (max_diff, mean_diff) in enumerate(zip(all_max, all_mean)):
+                if max_diff > DENSE_TOLERANCE_MAX_DIFF:
+                    failed_samples.append(
+                        f"Sample {sample_idx}: max_diff={max_diff:.6g} > {DENSE_TOLERANCE_MAX_DIFF}"
+                    )
+                if mean_diff > DENSE_TOLERANCE_MEAN_DIFF:
+                    failed_samples.append(
+                        f"Sample {sample_idx}: mean_diff={mean_diff:.6g} > {DENSE_TOLERANCE_MEAN_DIFF}"
+                    )
+
+            if failed_samples:
+                self.fail(
+                    f"Config {{'num_samples': {NUM_SAMPLES}, 'logprob_sample_ratio': {LOGPROB_SAMPLE_RATIO}, 'temperature': {TEMPERATURE}}} - Tolerance exceeded in {len(failed_samples)} samples:\n"
+                    + "\n".join(failed_samples[:5])
+                )
+
+
+if __name__ == "__main__":
+    unittest.main()