Fix mixed chunked prefill (#1850)

python/sglang/srt/managers/scheduler.py

@@ -720,9 +720,11 @@ def get_new_batch_prefill(self) -> Optional[ScheduleBatch]:
 
         # Mixed-style chunked prefill
         if self.is_mixed_chunk and self.running_batch is not None:
-            self.running_batch.prepare_for_decode(self.enable_overlap)
-            new_batch.mix_with_running(self.running_batch)
-            new_batch.decoding_reqs = self.running_batch.reqs
+            self.running_batch.filter_batch()
+            if not self.running_batch.is_empty():
+                self.running_batch.prepare_for_decode(self.enable_overlap)
+                new_batch.mix_with_running(self.running_batch)
+                new_batch.decoding_reqs = self.running_batch.reqs
             self.running_batch = None
         else:
             new_batch.decoding_reqs = None

python/sglang/test/test_utils.py

@@ -7,6 +7,7 @@
 import subprocess
 import threading
 import time
+from concurrent.futures import ThreadPoolExecutor
 from functools import partial
 from types import SimpleNamespace
 from typing import Callable, List, Optional
@@ -656,11 +657,12 @@ def read_output(output_lines):
         time.sleep(0.1)
 
 
-def run_mmlu_test(
+def run_and_check_memory_leak(
+    workload_func,
     disable_radix_cache,
-    enable_mixed_chunk=False,
-    enable_overlap=False,
-    chunked_prefill_size=32,
+    enable_mixed_chunk,
+    enable_overlap,
+    chunked_prefill_size,
 ):
     other_args = ["--chunked-prefill-size", str(chunked_prefill_size)]
     if disable_radix_cache:
@@ -690,21 +692,8 @@ def run_mmlu_test(
     t = threading.Thread(target=read_output, args=(output_lines,))
     t.start()
 
-    # Run the eval
-    args = SimpleNamespace(
-        base_url=base_url,
-        model=model,
-        eval_name="mmlu",
-        num_examples=128,
-        num_threads=128,
-    )
-
-    try:
-        metrics = run_eval(args)
-        print(f"{metrics=}")
-        assert metrics["score"] >= 0.65
-    finally:
-        pass
+    # Run the workload
+    workload_func(base_url, model)
 
     # Clean up everything
     kill_child_process(process.pid, include_self=True)
@@ -727,4 +716,63 @@ def run_mmlu_test(
             has_leak = True
 
     assert has_new_server
-    # assert not has_leak
+    assert not has_leak
+
+
+def run_mmlu_test(
+    disable_radix_cache=False,
+    enable_mixed_chunk=False,
+    enable_overlap=False,
+    chunked_prefill_size=32,
+):
+    def workload_func(base_url, model):
+        # Run the eval
+        args = SimpleNamespace(
+            base_url=base_url,
+            model=model,
+            eval_name="mmlu",
+            num_examples=128,
+            num_threads=128,
+        )
+
+        try:
+            metrics = run_eval(args)
+            print(f"{metrics=}")
+            assert metrics["score"] >= 0.65
+        finally:
+            pass
+
+    run_and_check_memory_leak(workload_func, disable_radix_cache, enable_mixed_chunk, enable_overlap, chunked_prefill_size)
+
+
+def run_mulit_request_test(
+    disable_radix_cache=False,
+    enable_mixed_chunk=False,
+    enable_overlap=False,
+    chunked_prefill_size=32,
+):
+
+    def workload_func(base_url, model):
+        def run_one(_):
+            prompt = """
+            System: You are a helpful assistant.
+            User: What is the capital of France?
+            Assistant: The capital of France is
+            """
+
+            response = requests.post(
+                f"{base_url}/generate",
+                json={
+                    "text": prompt,
+                    "sampling_params": {
+                        "temperature": 0,
+                        "max_new_tokens": 8,
+                    },
+                },
+            )
+            ret = response.json()
+
+        with ThreadPoolExecutor(2) as executor:
+            list(executor.map(run_one, list(range(4))))
+
+    run_and_check_memory_leak(workload_func, disable_radix_cache, enable_mixed_chunk, enable_overlap, chunked_prefill_size)

test/srt/test_chunked_prefill.py

@@ -8,6 +8,7 @@
     DEFAULT_MODEL_NAME_FOR_TEST,
     run_bench_serving,
     run_mmlu_test,
+    run_mulit_request_test,
 )
 
 
@@ -39,6 +40,12 @@ def test_no_chunked_prefill_without_radix_cache(self):
 
         assert res["completed"] == 10
 
+    def test_mixed_chunked_prefill_multi_requests(self):
+        run_mulit_request_test(
+            enable_mixed_chunk=True,
+            chunked_prefill_size=2048,
+        )
+
 
 if __name__ == "__main__":
     unittest.main()