test_async_llm_engine.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project

import asyncio
import os
import uuid
from asyncio import CancelledError
from copy import copy
from dataclasses import dataclass
from typing import Optional

import pytest
import pytest_asyncio
import torch

from vllm import SamplingParams
from vllm.config import ParallelConfig
from vllm.distributed import cleanup_dist_env_and_memory
from vllm.engine.async_llm_engine import AsyncEngineArgs, AsyncLLMEngine
from vllm.outputs import RequestOutput as RealRequestOutput
from vllm.sampling_params import RequestOutputKind

from ..utils import wait_for_gpu_memory_to_clear


@dataclass
class RequestOutput:
    request_id: int
    finished: bool = False


@dataclass
class MockModelConfig:
    use_async_output_proc = True


class MockEngine:

    def __init__(self):
        self.step_calls = 0
        self.add_request_calls = 0
        self.abort_request_calls = 0
        self.request_id = None
        # Ugly, remove dependency when possible
        self.parallel_config = ParallelConfig()
        self.model_config = MockModelConfig()

    async def step_async(self, virtual_engine):
        # PP size is 1, ignore virtual engine
        self.step_calls += 1
        return [RequestOutput(
            request_id=self.request_id)] if self.request_id else []

    async def process_model_inputs_async(self, *args, **kwargs):
        pass

    async def stop_remote_worker_execution_loop_async(self):
        pass

    def generate(self, request_id):
        self.request_id = request_id

    def stop_generating(self):
        self.request_id = None

    def add_request(self, **kwargs):
        del kwargs  # Unused
        self.add_request_calls += 1
        print(f'Request calls: {self.add_request_calls}')

    async def add_request_async(self, **kwargs):
        self.add_request_calls += 1
        return

    def abort_request(self, request_id):
        del request_id  # Unused
        self.abort_request_calls += 1

    def has_unfinished_requests(self):
        return self.request_id is not None

    def has_unfinished_requests_for_virtual_engine(self, virtual_engine):
        return self.request_id is not None


class MockAsyncLLMEngine(AsyncLLMEngine):
    _engine_class = MockEngine


@pytest.mark.asyncio
async def test_new_requests_event():
    params = SamplingParams()

    engine = MockAsyncLLMEngine()
    engine.start_background_loop()
    await asyncio.sleep(0.01)
    assert engine.engine.step_calls == 0

    await engine.add_request("1", "", params)
    await asyncio.sleep(0.01)
    assert engine.engine.add_request_calls == 1
    assert engine.engine.step_calls == 1

    await engine.add_request("2", "", params)
    engine.engine.generate("2")
    await asyncio.sleep(0)
    await asyncio.sleep(0)
    await asyncio.sleep(0)
    assert engine.engine.add_request_calls == 2
    assert engine.engine.step_calls >= 2
    await asyncio.sleep(0.001)
    assert engine.engine.step_calls >= 3
    engine.engine.stop_generating()
    await asyncio.sleep(0.001)
    old_step_calls = engine.engine.step_calls
    await asyncio.sleep(0.001)
    assert engine.engine.step_calls == old_step_calls

    await engine.add_request("3", "", params)
    await asyncio.sleep(0.01)
    assert engine.engine.add_request_calls == 3
    assert engine.engine.step_calls == old_step_calls + 1
    await asyncio.sleep(0.01)
    assert engine.engine.add_request_calls == 3
    assert engine.engine.step_calls == old_step_calls + 1

    engine = MockAsyncLLMEngine()
    assert engine.get_model_config() is not None
    assert engine.get_tokenizer() is not None
    assert engine.get_decoding_config() is not None


def start_engine():
    wait_for_gpu_memory_to_clear(
        devices=list(range(torch.cuda.device_count())),
        threshold_bytes=2 * 2**30,
        timeout_s=60,
    )

    num_scheduler_steps = int(os.getenv("NUM_SCHEDULER_STEPS", "1"))
    print(f"Starting engine with num_scheduler_steps={num_scheduler_steps}")

    return AsyncLLMEngine.from_engine_args(
        AsyncEngineArgs(model="facebook/opt-125m",
                        enforce_eager=True,
                        num_scheduler_steps=num_scheduler_steps))


def uid() -> str:
    return str(uuid.uuid4())


@pytest_asyncio.fixture(scope="module")
async def async_engine():
    # We cannot use monkeypatch since this is a module
    # scoped fixture and monkeypatch is function scoped.
    previous_value = os.getenv("VLLM_USE_V1", None)
    os.environ["VLLM_USE_V1"] = "0"
    engine = await asyncio.get_event_loop().run_in_executor(executor=None,
                                                            func=start_engine)
    try:
        yield engine
    finally:
        engine.shutdown_background_loop()
        del engine
        await asyncio.sleep(0.1)
        cleanup_dist_env_and_memory()

        if previous_value:
            os.environ["VLLM_USE_V1"] = previous_value
        else:
            del os.environ["VLLM_USE_V1"]


@pytest.fixture()
def should_do_global_cleanup_after_test(request) -> bool:
    # So we can share the async engine fixture between these tests
    return False


@pytest.mark.asyncio(scope="module")
@pytest.mark.parametrize("stop", [None, ["a stop string"]])
async def test_asyncio_run(async_engine, stop):

    scheduler_config = await async_engine.get_scheduler_config()
    num_scheduler_steps = scheduler_config.num_scheduler_steps

    async def run(prompt: str):
        sampling_params = SamplingParams(
            temperature=0,
            max_tokens=32,
            min_tokens=32,
            stop=stop,
        )

        output_count = 0
        final_output = None
        async for output in async_engine.generate(prompt,
                                                  sampling_params,
                                                  request_id=uid()):
            output_count += 1
            final_output = output
        return final_output, output_count

    results = await asyncio.gather(
        run("test0"),
        run("test0"),
    )
    assert len(results) == 2
    first, second = results

    # remove nondeterministic fields for comparison
    first[0].metrics = None
    second[0].metrics = None
    first[0].request_id = None
    second[0].request_id = None

    assert str(first) == str(second)

    output_count = results[0][1]
    if num_scheduler_steps == 1:
        assert output_count == 32
    else:
        assert 1 < output_count < 32


@pytest.mark.asyncio(scope="module")
@pytest.mark.parametrize("stop", [None, ["a stop string"]])
async def test_output_kinds(async_engine, stop):
    """Test that output_kind works as expected and that
    results are equivalent across different kinds."""

    scheduler_config = await async_engine.get_scheduler_config()
    num_scheduler_steps = scheduler_config.num_scheduler_steps

    sampling_params = SamplingParams(
        temperature=0,
        max_tokens=32,
        min_tokens=32,
        stop=stop,
    )

    async def run(prompt: str, kind: RequestOutputKind):
        params = copy(sampling_params)
        params.output_kind = kind

        output_count = 0
        final_output = None
        async for output in async_engine.generate(prompt,
                                                  params,
                                                  request_id=uid()):
            output_count += 1
            final_output = output

        assert final_output is not None
        assert final_output.finished

        return (final_output.prompt_token_ids,
                final_output.outputs[0].token_ids,
                final_output.outputs[0].text, output_count)

    async def run_deltas(prompt: str):
        params = copy(sampling_params)
        params.output_kind = RequestOutputKind.DELTA

        prompt_tokens = None
        output_tokens: list[int] = []
        output_text = ""
        output_count = 0
        final_output = None
        async for output in async_engine.generate(prompt,
                                                  params,
                                                  request_id=uid()):
            token_ids = output.outputs[0].token_ids
            text = output.outputs[0].text
            final_output = output

            # Ensure we get prompt ids iff we haven't yet received output tokens
            if output_tokens:
                assert 1 <= len(token_ids) <= num_scheduler_steps
                assert stop or text
                assert not output.prompt_token_ids
            else:
                assert output.prompt_token_ids
                prompt_tokens = output.prompt_token_ids

            output_tokens.extend(token_ids)
            output_text += text

            output_count += 1

        assert final_output is not None
        assert final_output.finished

        return prompt_tokens, output_tokens, output_text, output_count

    results = await asyncio.gather(
        run("common input prompt", RequestOutputKind.CUMULATIVE),
        run("common input prompt", RequestOutputKind.FINAL_ONLY),
        run_deltas("common input prompt"))

    # Make sure outputs are the same
    prompt_set = set(tuple(prompt_ids) for prompt_ids, _, _, _ in results)
    assert len(prompt_set) == 1

    text_set = set(text for _, _, text, _ in results)
    assert len(text_set) == 1

    tokens_set = set(tuple(ids) for _, ids, _, _ in results)
    assert len(tokens_set) == 1

    cumulative, final, deltas = results

    # output message counts
    assert cumulative[3] == deltas[3]

    if num_scheduler_steps == 1:
        assert cumulative[3] == 32
    else:
        assert 1 < cumulative[3] < 32

    assert final[3] == 1


@pytest.mark.asyncio(scope="module")
@pytest.mark.parametrize("stop", [None, ["a stop string"]])
async def test_cancellation(async_engine, stop):
    scheduler_config = await async_engine.get_scheduler_config()
    num_scheduler_steps = scheduler_config.num_scheduler_steps

    sampling_params = SamplingParams(
        temperature=0,
        min_tokens=13,
        max_tokens=13,
        stop=stop,
    )

    stop_at = 5 if num_scheduler_steps == 1 else 1

    request_id = uid()

    i = 0
    with pytest.raises(CancelledError):
        async for output in async_engine.generate("test2",
                                                  sampling_params,
                                                  request_id=request_id):
            assert not output.finished
            i += 1
            if i == stop_at:
                await async_engine.abort(request_id)

    assert i == stop_at


@pytest.mark.asyncio(scope="module")
@pytest.mark.parametrize("stop", [None, ["a stop string"]])
async def test_delayed_generator(async_engine, stop):
    scheduler_config = await async_engine.get_scheduler_config()

    if scheduler_config.num_scheduler_steps != 1:
        pytest.skip("no need to test this one with multistep")

    sampling_params = SamplingParams(
        temperature=0,
        min_tokens=10,
        max_tokens=10,
        stop=stop,
    )

    stream = async_engine.generate("test3", sampling_params, request_id=uid())
    i = 0
    final_output: Optional[RealRequestOutput] = None
    async for output in stream:
        final_output = output
        if i == 0:
            # wait for generation to complete before consuming
            # the remaining messages
            await asyncio.sleep(1)
        if i < 9:
            assert not output.finished
        i += 1

    assert i == 10
    assert final_output is not None
    assert len(final_output.outputs[0].token_ids) == 10
    assert final_output.finished