feat: add coordinated checkpoint prefetch for network filesystem loading (#20843)

test/registered/model_loading/test_prefetch_checkpoints_multi_gpu.py

@@ -0,0 +1,49 @@
+import unittest
+
+import sglang as sgl
+from sglang.test.ci.ci_register import register_cuda_ci
+from sglang.test.test_utils import CustomTestCase
+
+register_cuda_ci(est_time=300, suite="nightly-4-gpu")
+
+PROMPTS = [
+    "Hello, my name is",
+    "The president of the United States is",
+    "The capital of France is",
+    "The future of AI is",
+]
+
+
+class TestPrefetchCheckpointsMultiGPU(CustomTestCase):
+    """Verify that --weight-loader-prefetch-checkpoints works with DP attention."""
+
+    @classmethod
+    def setUpClass(cls):
+        cls.engine = sgl.Engine(
+            model_path="Qwen/Qwen1.5-MoE-A2.7B-Chat",
+            tp_size=4,
+            dp_size=4,
+            enable_dp_attention=True,
+            disable_radix_cache=True,
+            weight_loader_prefetch_checkpoints=True,
+            cuda_graph_max_bs=1,
+            max_total_tokens=256,
+        )
+
+    @classmethod
+    def tearDownClass(cls):
+        if hasattr(cls, "engine") and cls.engine:
+            cls.engine.shutdown()
+
+    def test_generate_with_prefetch(self):
+        """Server launched with prefetch must produce valid output."""
+        outputs = self.engine.generate(PROMPTS)
+        self.assertEqual(len(outputs), len(PROMPTS))
+        for i, output in enumerate(outputs):
+            text = output["text"]
+            self.assertIsInstance(text, str)
+            self.assertGreater(len(text), 0, f"Prompt {i} produced empty output")
+
+
+if __name__ == "__main__":
+    unittest.main()