[Core] Add multiproc_worker_utils for multiprocessing-based workers (#4357)

Author: njhill

tests/engine/test_multiproc_workers.py

@@ -0,0 +1,176 @@
+import asyncio
+from concurrent.futures import ThreadPoolExecutor
+from functools import partial
+from time import sleep
+from typing import Any, List, Tuple
+
+import pytest
+
+from vllm.executor.multiproc_worker_utils import (ProcessWorkerWrapper,
+                                                  ResultHandler, WorkerMonitor)
+
+
+class DummyWorker:
+    """Dummy version of vllm.worker.worker.Worker"""
+
+    def __init__(self, rank: int):
+        self.rank = rank
+
+    def worker_method(self, worker_input: Any) -> Tuple[int, Any]:
+        sleep(0.05)
+
+        if isinstance(worker_input, Exception):
+            # simulate error case
+            raise worker_input
+
+        return self.rank, input
+
+
+def _start_workers() -> Tuple[List[ProcessWorkerWrapper], WorkerMonitor]:
+    result_handler = ResultHandler()
+    workers = [
+        ProcessWorkerWrapper(result_handler, partial(DummyWorker, rank=rank))
+        for rank in range(8)
+    ]
+
+    worker_monitor = WorkerMonitor(workers, result_handler)
+    assert not worker_monitor.is_alive()
+
+    result_handler.start()
+    worker_monitor.start()
+    assert worker_monitor.is_alive()
+
+    return workers, worker_monitor
+
+
+def test_local_workers() -> None:
+    """Test workers with sync task submission"""
+
+    workers, worker_monitor = _start_workers()
+
+    def execute_workers(worker_input: str) -> None:
+        worker_outputs = [
+            worker.execute_method("worker_method", worker_input)
+            for worker in workers
+        ]
+
+        for rank, output in enumerate(worker_outputs):
+            assert output.get() == (rank, input)
+
+    executor = ThreadPoolExecutor(max_workers=4)
+
+    # Test concurrent submission from different threads
+    futures = [
+        executor.submit(partial(execute_workers, f"thread {thread_num}"))
+        for thread_num in range(4)
+    ]
+
+    for future in futures:
+        future.result()
+
+    # Test error case
+    exception = ValueError("fake error")
+    result = workers[0].execute_method("worker_method", exception)
+    try:
+        result.get()
+        pytest.fail("task should have failed")
+    except Exception as e:
+        assert isinstance(e, ValueError)
+        assert str(e) == "fake error"
+
+    # Test cleanup when a worker fails
+    assert worker_monitor.is_alive()
+    workers[3].process.kill()
+
+    # Other workers should get shut down here
+    worker_monitor.join(2)
+
+    # Ensure everything is stopped
+    assert not worker_monitor.is_alive()
+    assert all(not worker.process.is_alive() for worker in workers)
+
+    # Further attempts to submit tasks should fail
+    try:
+        _result = workers[0].execute_method("worker_method", "test")
+        pytest.fail("task should fail once workers have been shut down")
+    except Exception as e:
+        assert isinstance(e, ChildProcessError)
+
+
+def test_local_workers_clean_shutdown() -> None:
+    """Test clean shutdown"""
+
+    workers, worker_monitor = _start_workers()
+
+    assert worker_monitor.is_alive()
+    assert all(worker.process.is_alive() for worker in workers)
+
+    # Clean shutdown
+    worker_monitor.close()
+
+    worker_monitor.join(5)
+
+    # Ensure everything is stopped
+    assert not worker_monitor.is_alive()
+    assert all(not worker.process.is_alive() for worker in workers)
+
+    # Further attempts to submit tasks should fail
+    try:
+        _result = workers[0].execute_method("worker_method", "test")
+        pytest.fail("task should fail once workers have been shut down")
+    except Exception as e:
+        assert isinstance(e, ChildProcessError)
+
+
+@pytest.mark.asyncio
+async def test_local_workers_async() -> None:
+    """Test local workers with async task submission"""
+
+    workers, worker_monitor = _start_workers()
+
+    async def execute_workers(worker_input: str) -> None:
+        worker_coros = [
+            worker.execute_method_async("worker_method", worker_input)
+            for worker in workers
+        ]
+
+        results = await asyncio.gather(*worker_coros)
+        for rank, result in enumerate(results):
+            assert result == (rank, input)
+
+    tasks = [
+        asyncio.create_task(execute_workers(f"task {task_num}"))
+        for task_num in range(4)
+    ]
+
+    for task in tasks:
+        await task
+
+    # Test error case
+    exception = ValueError("fake error")
+    try:
+        _result = await workers[0].execute_method_async(
+            "worker_method", exception)
+        pytest.fail("task should have failed")
+    except Exception as e:
+        assert isinstance(e, ValueError)
+        assert str(e) == "fake error"
+
+    # Test cleanup when a worker fails
+    assert worker_monitor.is_alive()
+    workers[3].process.kill()
+
+    # Other workers should get shut down here
+    worker_monitor.join(2)
+
+    # Ensure everything is stopped
+    assert not worker_monitor.is_alive()
+    assert all(not worker.process.is_alive() for worker in workers)
+
+    # Further attempts to submit tasks should fail
+    try:
+        _result = await workers[0].execute_method_async(
+            "worker_method", "test")
+        pytest.fail("task should fail once workers have been shut down")
+    except Exception as e:
+        assert isinstance(e, ChildProcessError)