Implement LRU eviction policy for LoRA adapters (#11041)

test/srt/lora/test_lora_eviction_policy.py

@@ -0,0 +1,190 @@
+# Copyright 2023-2024 SGLang Team
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+
+"""
+Unit tests for LoRA eviction policies.
+Tests LRU and FIFO eviction behavior.
+"""
+
+import unittest
+
+from sglang.srt.lora.eviction_policy import get_eviction_policy
+
+
+class TestLoRAEvictionPolicy(unittest.TestCase):
+    """Unit tests for LoRA eviction policies."""
+
+    def _test_eviction_policy(
+        self, policy_name, access_sequence, candidates, expected_victim
+    ):
+        """
+        Helper to test eviction policy with given access pattern.
+
+        Args:
+            policy_name: Name of eviction policy ("lru" or "fifo")
+            access_sequence: List of adapter IDs in access order
+            candidates: Set of adapter IDs that can be evicted
+            expected_victim: Expected adapter ID to be evicted
+        """
+        policy = get_eviction_policy(policy_name)
+
+        # Simulate access pattern
+        for adapter_id in access_sequence:
+            policy.mark_used(adapter_id)
+
+        # Select victim from candidates
+        victim = policy.select_victim(candidates)
+        self.assertEqual(
+            victim,
+            expected_victim,
+            f"{policy_name.upper()}: Expected {expected_victim}, got {victim}",
+        )
+
+    def test_lru_basic(self):
+        """Test LRU selects least recently used adapter."""
+        self._test_eviction_policy(
+            "lru",
+            access_sequence=["lora1", "lora2", "lora3", "lora4"],
+            candidates={"lora1", "lora2", "lora3", "lora4"},
+            expected_victim="lora1",
+        )
+
+    def test_lru_with_reuse(self):
+        """Test LRU updates order on reuse."""
+        self._test_eviction_policy(
+            "lru",
+            access_sequence=["lora1", "lora2", "lora3", "lora4", "lora1"],
+            candidates={"lora1", "lora2", "lora3", "lora4"},
+            expected_victim="lora2",
+        )
+
+    def test_lru_multiple_reuse(self):
+        """Test LRU with multiple reuses."""
+        self._test_eviction_policy(
+            "lru",
+            access_sequence=["lora1", "lora2", "lora3", "lora1", "lora2"],
+            candidates={"lora1", "lora2", "lora3"},
+            expected_victim="lora3",
+        )
+
+    def test_lru_with_subset_candidates(self):
+        """Test LRU with subset of candidates."""
+        self._test_eviction_policy(
+            "lru",
+            access_sequence=["lora1", "lora2", "lora3", "lora4"],
+            candidates={"lora2", "lora3", "lora4"},
+            expected_victim="lora2",
+        )
+
+    def test_lru_base_model_priority(self):
+        """Test LRU prioritizes base model for eviction."""
+        self._test_eviction_policy(
+            "lru",
+            access_sequence=["lora1", "lora2", "lora3"],
+            candidates={None, "lora1", "lora2", "lora3"},
+            expected_victim=None,
+        )
+
+    def test_fifo_basic(self):
+        """Test FIFO selects first inserted adapter."""
+        self._test_eviction_policy(
+            "fifo",
+            access_sequence=["lora1", "lora2", "lora3", "lora4"],
+            candidates={"lora1", "lora2", "lora3", "lora4"},
+            expected_victim="lora1",
+        )
+
+    def test_fifo_ignores_reuse(self):
+        """Test FIFO ignores reuse."""
+        self._test_eviction_policy(
+            "fifo",
+            access_sequence=[
+                "lora1",
+                "lora2",
+                "lora3",
+                "lora4",
+                "lora4",
+                "lora3",
+                "lora2",
+                "lora1",
+            ],
+            candidates={"lora1", "lora2", "lora3", "lora4"},
+            expected_victim="lora1",
+        )
+
+    def test_fifo_with_subset_candidates(self):
+        """Test FIFO with subset of candidates."""
+        self._test_eviction_policy(
+            "fifo",
+            access_sequence=["lora1", "lora2", "lora3", "lora4"],
+            candidates={"lora2", "lora3", "lora4"},
+            expected_victim="lora2",
+        )
+
+    def test_fifo_base_model_priority(self):
+        """Test FIFO prioritizes base model for eviction."""
+        self._test_eviction_policy(
+            "fifo",
+            access_sequence=["lora1", "lora2", "lora3"],
+            candidates={None, "lora1", "lora2", "lora3"},
+            expected_victim=None,
+        )
+
+    def test_policy_remove(self):
+        """Test that remove() correctly updates internal state."""
+        lru = get_eviction_policy("lru")
+        lru.mark_used("lora1")
+        lru.mark_used("lora2")
+        lru.mark_used("lora3")
+
+        # Remove lora1, so lora2 becomes LRU
+        lru.remove("lora1")
+        victim = lru.select_victim({"lora1", "lora2", "lora3"})
+        self.assertEqual(victim, "lora2")
+
+    def test_eviction_policy_factory(self):
+        """Test eviction policy factory function."""
+        # Test valid policies
+        lru = get_eviction_policy("lru")
+        fifo = get_eviction_policy("fifo")
+
+        self.assertIsNotNone(lru)
+        self.assertIsNotNone(fifo)
+
+        # Test invalid policy
+        with self.assertRaises(ValueError):
+            get_eviction_policy("invalid_policy")
+
+    def test_lru_vs_fifo_behavior(self):
+        """Test that LRU and FIFO behave differently."""
+        access_sequence = ["lora1", "lora2", "lora3", "lora1"]
+        candidates = {"lora1", "lora2", "lora3"}
+
+        lru = get_eviction_policy("lru")
+        for adapter_id in access_sequence:
+            lru.mark_used(adapter_id)
+        lru_victim = lru.select_victim(candidates)
+
+        fifo = get_eviction_policy("fifo")
+        for adapter_id in access_sequence:
+            fifo.mark_used(adapter_id)
+        fifo_victim = fifo.select_victim(candidates)
+
+        self.assertNotEqual(lru_victim, fifo_victim)
+        self.assertEqual(lru_victim, "lora2")
+        self.assertEqual(fifo_victim, "lora1")
+
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)

test/srt/run_suite.py

@@ -20,6 +20,8 @@ suites = {
         TestFile("hicache/test_hicache_mla.py", 127),
         TestFile("hicache/test_hicache_storage.py", 127),
         TestFile("lora/test_lora.py", 200),
+        TestFile("lora/test_lora_eviction.py", 200),
+        TestFile("lora/test_lora_eviction_policy.py", 200),
         TestFile("lora/test_lora_backend.py", 99),
         TestFile("lora/test_lora_eviction.py", 200),
         TestFile("lora/test_lora_qwen3.py", 97),