Support Async Load (

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "truss"
-version = "0.9.56rc3"
+version = "0.9.56dev100"
 description = "A seamless bridge from model development to model delivery"
 license = "MIT"
 readme = "README.md"

truss/templates/server/model_wrapper.py

@@ -16,7 +16,6 @@
 from functools import cached_property
 from multiprocessing import Lock
 from pathlib import Path
-from threading import Thread
 from typing import (
     Any,
     Callable,
@@ -39,6 +38,7 @@
 from shared import dynamic_config_resolver, serialization
 from shared.lazy_data_resolver import LazyDataResolver
 from shared.secrets_resolver import SecretsResolver
+from tenacity import AsyncRetrying, stop_after_attempt, wait_fixed
 
 if sys.version_info >= (3, 9):
     from typing import AsyncGenerator, Generator
@@ -338,23 +338,19 @@ def ready(self) -> bool:
     def _model_file_name(self) -> str:
         return self._config["model_class_filename"]
 
-    def start_load_thread(self):
-        # Don't retry failed loads.
-        if self._status == ModelWrapper.Status.NOT_READY:
-            thread = Thread(target=self.load)
-            thread.start()
-
-    def load(self):
+    async def load(self):
         if self.ready:
             return
+
         # if we are already loading, block on acquiring the lock;
         # this worker will return 503 while the worker with the lock is loading
         with self._load_lock:
             self._status = ModelWrapper.Status.LOADING
             self._logger.info("Executing model.load()...")
             try:
                 start_time = time.perf_counter()
-                self._load_impl()
+                await self.try_load()
+
                 self._status = ModelWrapper.Status.READY
                 self._logger.info(
                     f"Completed model.load() execution in {_elapsed_ms(start_time)} ms"
@@ -363,7 +359,15 @@ def load(self):
                 self._logger.exception("Exception while loading model")
                 self._status = ModelWrapper.Status.FAILED
 
-    def _load_impl(self):
+    async def start_load(self):
+        if self.should_load():
+            asyncio.create_task(self.load())
+
+    def should_load(self) -> bool:
+        # don't retry failed loads
+        return not self._status == ModelWrapper.Status.FAILED and not self.ready
+
+    def _initialize_model(self):
         data_dir = Path("data")
         data_dir.mkdir(exist_ok=True)
 
@@ -446,17 +450,33 @@ def _load_impl(self):
 
         self._maybe_model_descriptor = ModelDescriptor.from_model(self._model)
 
+    async def try_load(self):
+        await to_thread.run_sync(self._initialize_model)
+
         if self._maybe_model_descriptor.setup_environment:
             self._initialize_environment_before_load()
 
         if hasattr(self._model, "load"):
-            retry(
-                self._model.load,
-                NUM_LOAD_RETRIES,
-                self._logger.warning,
-                "Failed to load model.",
-                gap_seconds=1.0,
-            )
+            if inspect.iscoroutinefunction(self._model.load):
+                async for attempt in AsyncRetrying(
+                    stop=stop_after_attempt(NUM_LOAD_RETRIES),
+                    wait=wait_fixed(1),
+                    before_sleep=lambda retry_state: self._logger.info(
+                        f"Model load failed (attempt {retry_state.attempt_number})...retrying"
+                    ),
+                ):
+                    with attempt:
+                        (await self._model.load(),)
+
+            else:
+                await to_thread.run_sync(
+                    retry,
+                    self._model.load,
+                    NUM_LOAD_RETRIES,
+                    self._logger.warn,
+                    "Failed to load model.",
+                    1.0,
+                )
 
     def setup_polling_for_environment_updates(self):
         self._poll_for_environment_updates_task = asyncio.create_task(

truss/templates/server/requirements.txt

@@ -16,6 +16,7 @@ psutil==5.9.4
 python-json-logger==2.0.2
 pyyaml==6.0.0
 requests==2.31.0
+tenacity==9.0.0
 uvicorn==0.24.0
 uvloop==0.19.0
 aiofiles==24.1.0

truss/templates/server/truss_server.py

@@ -275,15 +275,16 @@ def cleanup(self):
         if INFERENCE_SERVER_FAILED_FILE.exists():
             INFERENCE_SERVER_FAILED_FILE.unlink()
 
-    def on_startup(self):
+    async def on_startup(self):
         """
         This method will be started inside the main process, so here is where
         we want to setup our logging and model.
         """
         self.cleanup()
         if self._setup_json_logger:
             setup_logging()
-        self._model.start_load_thread()
+
+        await self._model.start_load()
         asyncio.create_task(self._shutdown_if_load_fails())
         self._model.setup_polling_for_environment_updates()
 

truss/tests/templates/server/test_model_wrapper.py

@@ -52,15 +52,15 @@ async def test_model_wrapper_load_error_once(app_path):
     config = yaml.safe_load((app_path / "config.yaml").read_text())
     os.chdir(app_path)
     model_wrapper = model_wrapper_class(config, sdk_trace.NoOpTracer())
-    model_wrapper.load()
+    await model_wrapper.load()
     # Allow load thread to execute
     time.sleep(1)
     output = await model_wrapper.predict({}, MagicMock(spec=Request))
     assert output == {}
     assert model_wrapper._model.load_count == 2
 
 
-def test_model_wrapper_load_error_more_than_allowed(app_path, helpers):
+async def test_model_wrapper_load_error_more_than_allowed(app_path, helpers):
     with helpers.env_var("NUM_LOAD_RETRIES_TRUSS", "0"):
         if "model_wrapper" in sys.modules:
             model_wrapper_module = sys.modules["model_wrapper"]
@@ -71,7 +71,7 @@ def test_model_wrapper_load_error_more_than_allowed(app_path, helpers):
         config = yaml.safe_load((app_path / "config.yaml").read_text())
         os.chdir(app_path)
         model_wrapper = model_wrapper_class(config, sdk_trace.NoOpTracer())
-        model_wrapper.load()
+        await model_wrapper.load()
         # Allow load thread to execute
         time.sleep(1)
         assert model_wrapper.load_failed
@@ -109,7 +109,8 @@ async def test_trt_llm_truss_init_extension(trt_llm_truss_container_fs, helpers)
             model_wrapper_module, "_init_extension", return_value=mock_extension
         ) as mock_init_extension:
             model_wrapper = model_wrapper_class(config, sdk_trace.NoOpTracer())
-            model_wrapper.load()
+            await model_wrapper.load()
+
             called_with_specific_extension = any(
                 call_args[0][0] == "trt_llm"
                 for call_args in mock_init_extension.call_args_list
@@ -146,8 +147,10 @@ async def mock_predict(return_value, request):
             model_wrapper_module, "_init_extension", return_value=mock_extension
         ):
             model_wrapper = model_wrapper_class(config, sdk_trace.NoOpTracer())
-            model_wrapper.load()
+            await model_wrapper.load()
+
             resp = await model_wrapper.predict({}, MagicMock(spec=Request))
+
             mock_extension.load.assert_called()
             mock_extension.model_args.assert_called()
             assert mock_predict_called
@@ -183,8 +186,10 @@ async def mock_predict(return_value, request: Request):
             model_wrapper_module, "_init_extension", return_value=mock_extension
         ):
             model_wrapper = model_wrapper_class(config, sdk_trace.NoOpTracer())
-            model_wrapper.load()
+            await model_wrapper.load()
+
             resp = await model_wrapper.predict({}, MagicMock(spec=Request))
+
             mock_extension.load.assert_called()
             mock_extension.model_override.assert_called()
             assert mock_predict_called

truss/tests/test_model_inference.py

@@ -738,6 +738,72 @@ def test_truss_with_error_stacktrace(test_data_path):
         )
 
 
+@pytest.mark.integration
+def test_async_load_truss():
+    model = """
+    import asyncio
+
+    class Model:
+        async def load(self):
+            await asyncio.sleep(5)
+
+        def predict(self, request):
+            return {"a": "b"}
+    """
+
+    config = "model_name: async-load-truss"
+
+    with ensure_kill_all(), tempfile.TemporaryDirectory(dir=".") as tmp_work_dir:
+        truss_dir = Path(tmp_work_dir, "truss")
+
+        create_truss(truss_dir, config, textwrap.dedent(model))
+
+        tr = TrussHandle(truss_dir)
+        _ = tr.docker_run(local_port=8090, detach=True, wait_for_server_ready=False)
+
+        truss_server_addr = "http://localhost:8090"
+
+        def _test_liveness_probe(expected_code):
+            live = requests.get(f"{truss_server_addr}/", timeout=1)
+            assert live.status_code == expected_code
+
+        def _test_readiness_probe(expected_code):
+            ready = requests.get(f"{truss_server_addr}/v1/models/model", timeout=1)
+            assert ready.status_code == expected_code
+
+        def _test_ping(expected_code):
+            ping = requests.get(f"{truss_server_addr}/ping", timeout=1)
+            assert ping.status_code == expected_code
+
+        def _test_predict(expected_code):
+            invocations = requests.post(
+                f"{truss_server_addr}/v1/models/model:predict", json={}, timeout=1
+            )
+            assert invocations.status_code == expected_code
+
+        SERVER_WARMUP_TIME = 3
+        LOAD_TEST_TIME = 2
+        LOAD_BUFFER_TIME = 5
+
+        # Sleep a few seconds to get the server some time to wake up
+        time.sleep(SERVER_WARMUP_TIME)
+
+        # The truss takes about 5 seconds to load.
+        # We want to make sure that it's not ready for that time.
+        for _ in range(LOAD_TEST_TIME):
+            _test_liveness_probe(200)
+            _test_readiness_probe(503)
+            _test_ping(503)
+            _test_predict(503)
+            time.sleep(1)
+
+        time.sleep(LOAD_BUFFER_TIME)
+        _test_liveness_probe(200)
+        _test_readiness_probe(200)
+        _test_ping(200)
+        _test_predict(200)
+
+
 @pytest.mark.integration
 def test_slow_truss(test_data_path):
     with ensure_kill_all():