[Feature] Speculative decoding support lookahead (#9873)

Co-authored-by: a4zhangfei <a4zhangfei@qq.com>
Co-authored-by: Qiaolin-Yu <liin1211@outlook.com>

test/srt/run_suite.py

@@ -78,6 +78,7 @@ suites = {
         TestFile("test_hidden_states.py", 55),
         TestFile("test_hybrid_attn_backend.py", 100),
         TestFile("test_standalone_speculative_decoding.py", 250),
+        TestFile("test_lookahead_speculative_decoding.py", 250),
         TestFile("test_input_embeddings.py", 38),
         TestFile("test_io_struct.py", 8),
         TestFile("test_jinja_template_utils.py", 1),

test/srt/test_lookahead_speculative_decoding.py

@@ -0,0 +1,107 @@
+import os
+import unittest
+from types import SimpleNamespace
+
+import requests
+
+from sglang.srt.utils import kill_process_tree
+from sglang.test.few_shot_gsm8k import run_eval as run_eval_few_shot_gsm8k
+from sglang.test.test_utils import (
+    DEFAULT_LOOKAHEAD_SPECULATIVE_TARGET_MODEL_FOR_TEST,
+    DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
+    DEFAULT_URL_FOR_TEST,
+    CustomTestCase,
+    popen_launch_server,
+)
+
+GSM_DATASET_PATH = None
+
+
+# Default server arguments shared across all tests
+DEFAULT_SERVER_ARGS = [
+    "--trust-remote-code",
+    "--cuda-graph-max-bs",
+    "8",
+    "--speculative-algorithm",
+    "LOOKAHEAD",
+    "--speculative-num-draft-tokens",
+    "16",
+    "--mem-fraction-static",
+    0.8,
+]
+
+
+class TestStandaloneSpeculativeDecodingBase(CustomTestCase):
+
+    model = DEFAULT_LOOKAHEAD_SPECULATIVE_TARGET_MODEL_FOR_TEST
+    base_url = DEFAULT_URL_FOR_TEST
+    accuracy_threshold = 0.8  # derived tests need to override this
+    spec_decode_threshold = 1.8  # derived spec decoding tests need to override this
+
+    @classmethod
+    def get_server_args(cls):
+        """Return the arguments for the server launch. Override in subclasses."""
+        return DEFAULT_SERVER_ARGS + ["--attention-backend", "fa3"]
+
+    @classmethod
+    def setUpClass(cls):
+        # disable deep gemm precompile to make launch server faster
+        # please don't do this if you want to make your inference workload faster
+        os.environ["SGL_JIT_DEEPGEMM_PRECOMPILE"] = "false"
+        os.environ["SGL_ENABLE_JIT_DEEPGEMM"] = "false"
+        model = cls.model
+        cls.process = popen_launch_server(
+            model,
+            cls.base_url,
+            timeout=DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
+            other_args=cls.get_server_args(),
+        )
+
+    @classmethod
+    def tearDownClass(cls):
+        kill_process_tree(cls.process.pid)
+
+    def test_gsm8k(self):
+        requests.get(self.base_url + "/flush_cache")
+
+        args = SimpleNamespace(
+            num_shots=4,
+            num_questions=100,
+            max_new_tokens=512,
+            parallel=128,
+            host="http://127.0.0.1",
+            port=int(self.base_url.split(":")[-1]),
+            data_path=GSM_DATASET_PATH,
+        )
+        metrics = run_eval_few_shot_gsm8k(args)
+        print(f"{metrics=}")
+
+        # Use the appropriate metric key based on the test class
+        metric_key = "accuracy"
+        self.assertGreater(metrics[metric_key], self.accuracy_threshold)
+
+        server_info = requests.get(self.base_url + "/get_server_info")
+        avg_spec_accept_length = server_info.json()["internal_states"][0][
+            "avg_spec_accept_length"
+        ]
+        print(f"{avg_spec_accept_length=}")
+        self.assertGreater(avg_spec_accept_length, self.spec_decode_threshold)
+
+
+class TestStandaloneSpeculativeDecodingTriton(TestStandaloneSpeculativeDecodingBase):
+
+    @classmethod
+    def get_server_args(cls):
+        return DEFAULT_SERVER_ARGS + ["--attention-backend", "triton"]
+
+
+class TestStandaloneSpeculativeDecodingFlashinfer(
+    TestStandaloneSpeculativeDecodingBase
+):
+    @classmethod
+    def get_server_args(cls):
+        return DEFAULT_SERVER_ARGS + ["--attention-backend", "flashinfer"]
+
+
+if __name__ == "__main__":
+    unittest.main()