[V1] Adding min tokens/repetition/presence/frequence penalties to V1 …

…sampler (vllm-project#10681)

Signed-off-by: Sourashis Roy <[email protected]>
Signed-off-by: Woosuk Kwon <[email protected]>
Co-authored-by: Woosuk Kwon <[email protected]>

tests/v1/engine/test_engine_core.py

@@ -139,3 +139,41 @@ def test_engine_core(monkeypatch):
         engine_core.abort_requests([req2.request_id, req0.request_id])
         assert len(engine_core.scheduler.waiting) == 0
         assert len(engine_core.scheduler.running) == 0
+
+
+def test_engine_core_advanced_sampling(monkeypatch):
+    """
+    A basic end-to-end test to verify that the engine functions correctly 
+    when additional sampling parameters, such as min_tokens and 
+    presence_penalty, are set.
+    """
+    with monkeypatch.context() as m:
+        m.setenv("VLLM_USE_V1", "1")
+        """Setup the EngineCore."""
+        engine_args = EngineArgs(model=MODEL_NAME)
+        vllm_config = engine_args.create_engine_config(
+            usage_context=UsageContext.UNKNOWN_CONTEXT)
+        executor_class = AsyncLLM._get_executor_cls(vllm_config)
+
+        engine_core = EngineCore(vllm_config=vllm_config,
+                                 executor_class=executor_class,
+                                 usage_context=UsageContext.UNKNOWN_CONTEXT)
+        """Test basic request lifecycle."""
+        # First request.
+        request: EngineCoreRequest = make_request()
+        request.sampling_params = SamplingParams(
+            min_tokens=4,
+            presence_penalty=1.0,
+            frequency_penalty=1.0,
+            repetition_penalty=0.1,
+            stop_token_ids=[1001, 1002],
+        )
+        engine_core.add_request(request)
+        assert len(engine_core.scheduler.waiting) == 1
+        assert len(engine_core.scheduler.running) == 0
+        # Loop through until they are all done.
+        while len(engine_core.step()) > 0:
+            pass
+
+        assert len(engine_core.scheduler.waiting) == 0
+        assert len(engine_core.scheduler.running) == 0

tests/v1/sample/test_sampler.py

@@ -0,0 +1,331 @@
+from typing import List, Set, Tuple
+
+import numpy as np
+import pytest
+import torch
+
+from vllm.utils import make_tensor_with_pad
+from vllm.v1.sample.metadata import SamplingMetadata
+from vllm.v1.sample.sampler import Sampler
+
+VOCAB_SIZE = 1024
+NUM_OUTPUT_TOKENS = 20
+CUDA_DEVICES = [
+    f"cuda:{i}" for i in range(1 if torch.cuda.device_count() == 1 else 2)
+]
+MAX_NUM_PROMPT_TOKENS = 64
+
+
+def _create_fake_logits(batch_size: int, vocab_size: int) -> torch.Tensor:
+    fake_logits = torch.full((batch_size, vocab_size), 1e-2, dtype=torch.float)
+    return fake_logits
+
+
+def _create_penalty_tensor(batch_size: int, penalty_value: float,
+                           device: torch.device) -> torch.Tensor:
+    return torch.full((batch_size, ),
+                      fill_value=penalty_value,
+                      dtype=torch.float,
+                      device=device)
+
+
+def _create_prompt_tokens_tensor(
+    prompt_token_ids: List[List[int]],
+    vocab_size: int,
+    device: torch.device,
+) -> torch.Tensor:
+    return make_tensor_with_pad(
+        prompt_token_ids,
+        pad=vocab_size,
+        device=device,
+        dtype=torch.int64,
+        pin_memory=False,
+    )
+
+
+def _create_default_sampling_metadata(
+    num_output_tokens: int,
+    batch_size: int,
+    vocab_size: int,
+    device: torch.device,
+) -> SamplingMetadata:
+    output_token_ids: List[List[int]] = []
+    prompt_token_ids: List[List[int]] = []
+    for _ in range(batch_size):
+        output_token_ids.append(
+            np.random.randint(0, vocab_size, size=num_output_tokens).tolist())
+        prompt_token_ids.append(
+            np.random.randint(0,
+                              vocab_size,
+                              size=np.random.randint(
+                                  1, MAX_NUM_PROMPT_TOKENS)).tolist())
+    fake_sampling_metadata = SamplingMetadata(
+        temperature=torch.full((batch_size, ), 0.0),
+        all_greedy=True,
+        all_random=False,
+        top_p=torch.empty(batch_size, ),
+        top_k=torch.empty(batch_size, ),
+        no_top_p=True,
+        no_top_k=True,
+        generators={},
+        max_num_logprobs=VOCAB_SIZE,
+        prompt_token_ids=_create_prompt_tokens_tensor(prompt_token_ids,
+                                                      vocab_size, device),
+        output_token_ids=output_token_ids,
+        frequency_penalties=_create_penalty_tensor(batch_size, 0.0, device),
+        presence_penalties=_create_penalty_tensor(batch_size, 0.0, device),
+        repetition_penalties=_create_penalty_tensor(batch_size, 1.0, device),
+        no_penalties=True,
+        min_tokens=[],
+        stop_token_ids=[],
+    )
+    return fake_sampling_metadata
+
+
+def _generate_min_token_penalties_and_stop_tokens(
+    num_output_tokens: int, batch_size: int, vocab_size: int,
+    batch_indices_for_min_token_penalty: List[int]
+) -> Tuple[List[int], List[Set[int]]]:
+    """
+    Generates and returns a list of minimum token penalties (`min_tokens`) 
+    and a corresponding list of stop token IDs (`stop_token_ids`) for each 
+    batch.
+
+    If a batch index is included in `batch_indices_for_min_token_penalty`, 
+    a higher `min_tokens` value is assigned (within a randomized range), 
+    and a random set of stop token IDs is created. Otherwise, a lower 
+    `min_tokens` value is assigned, and the stop token IDs set is empty.   
+    """
+    stop_token_ids: List[Set[int]] = []
+    min_tokens: List[int] = []
+    for index in range(batch_size):
+        if index in batch_indices_for_min_token_penalty:
+            min_tokens.append(
+                np.random.randint(num_output_tokens + 1,
+                                  2 * num_output_tokens))
+            stop_token_ids.append(
+                set(
+                    np.random.randint(0, vocab_size - 1)
+                    for _ in range(np.random.randint(0, vocab_size))))
+
+        else:
+            min_tokens.append(np.random.randint(0, num_output_tokens))
+            stop_token_ids.append(set())
+    return (min_tokens, stop_token_ids)
+
+
+def _create_weighted_output_token_list(
+        batch_size: int,
+        vocab_size: int) -> Tuple[List[List[int]], List[List[int]]]:
+    """
+    Creates an output token list where each token occurs a distinct 
+    number of times.
+
+    For each batch, a random subset of token IDs is selected from the
+    vocabulary. The selected tokens are then added to the output token
+    list, each with a different frequency.
+
+    Returns:
+        Tuple[List[List[int]], List[List[int]]]:
+            - The first element is the output token list, where each sublist 
+              corresponds to a batch and contains tokens with weighted 
+              frequencies.
+            - The second element is a list of distinct token IDs for each
+              batch, ordered by their frequency in the corresponding output
+              list.
+    """
+    output_token_ids: List[List[int]] = []
+    sorted_token_ids_in_output: List[List[int]] = []
+    for _ in range(batch_size):
+        distinct_token_ids = np.random.choice(vocab_size,
+                                              size=np.random.randint(1, 10),
+                                              replace=False).tolist()
+        sorted_token_ids_in_output.append(distinct_token_ids)
+        output_token_ids_for_batch = []
+        for index, token_id in enumerate(distinct_token_ids):
+            output_token_ids_for_batch.extend(
+                [token_id for _ in range(index + 1)])
+        output_token_ids.append(output_token_ids_for_batch)
+    return (output_token_ids, sorted_token_ids_in_output)
+
+
+@pytest.mark.parametrize("device", CUDA_DEVICES)
+@pytest.mark.parametrize("batch_size", [1, 2, 32])
+def test_sampler_min_tokens_penalty(device: str, batch_size: int):
+    """
+    Tests that if the number of output tokens is less than 
+    SamplingParams.min_tokens then we will set the logits for
+    the stop token ids to -inf.
+    """
+    torch.set_default_device(device)
+    fake_logits = _create_fake_logits(batch_size, VOCAB_SIZE)
+    sampling_metadata = _create_default_sampling_metadata(
+        NUM_OUTPUT_TOKENS, batch_size, VOCAB_SIZE, torch.device(device))
+    batch_indices_for_min_token_penalty = np.random.randint(
+        0, batch_size - 1, size=np.random.randint(0, batch_size)).tolist()
+    min_tokens, stop_token_ids = _generate_min_token_penalties_and_stop_tokens(
+        NUM_OUTPUT_TOKENS, batch_size, VOCAB_SIZE,
+        batch_indices_for_min_token_penalty)
+    sampling_metadata.min_tokens = min_tokens
+    sampling_metadata.stop_token_ids = stop_token_ids
+    sampler = Sampler()
+    sampler_output = sampler(fake_logits, sampling_metadata)
+    for batch_idx in range(batch_size):
+        for vocab in range(VOCAB_SIZE):
+            # Verify that the logprobs for stop token ids is set
+            # to -inf.
+            logprob_index = torch.where(
+                sampler_output.logprob_token_ids[batch_idx] ==
+                vocab)[0].item()
+            if vocab in stop_token_ids[batch_idx]:
+                assert sampler_output.logprobs[batch_idx][
+                    logprob_index] == -float("inf")
+            else:
+                assert sampler_output.logprobs[batch_idx][
+                    logprob_index] != -float("inf")
+
+
+@pytest.mark.parametrize("device", CUDA_DEVICES)
+@pytest.mark.parametrize("batch_size", [1, 2, 32])
+@pytest.mark.parametrize("presence_penalty", [-2.0, 2.0])
+def test_sampler_presence_penalty(device: str, batch_size: int,
+                                  presence_penalty: float):
+    """
+    Test to verify that if presence penalty is enabled then tokens
+    are penalized as per their presence in the existing output.
+    """
+    torch.set_default_device(device)
+    # Create fake logits where each token is assigned the same
+    # logit value.
+    fake_logits = _create_fake_logits(batch_size, VOCAB_SIZE)
+    sampling_metadata = _create_default_sampling_metadata(
+        NUM_OUTPUT_TOKENS, batch_size, VOCAB_SIZE, torch.device(device))
+    output_token_ids = sampling_metadata.output_token_ids
+    sampling_metadata.presence_penalties = _create_penalty_tensor(
+        batch_size, presence_penalty, torch.device(device))
+    sampling_metadata.no_penalties = False
+    sampler = Sampler()
+    sampler_output = sampler(fake_logits, sampling_metadata)
+    for batch_idx in range(batch_size):
+        # The logprobs in the SamplerOutput are arranged in descending order.
+        # Since all tokens initially have the same logprobs, the non-penalized
+        # tokens will appear at the beginning, while the penalized tokens
+        #  will appear at the end of the list.
+        penalized_token_id = sampler_output.logprob_token_ids[batch_idx][
+            VOCAB_SIZE - 1]
+        penalized_log_prod = sampler_output.logprobs[batch_idx][VOCAB_SIZE - 1]
+        non_penalized_token_id = sampler_output.logprob_token_ids[batch_idx][0]
+        non_penalized_log_prod = sampler_output.logprobs[batch_idx][0]
+        assert non_penalized_log_prod > penalized_log_prod
+        if presence_penalty > 0:
+            # If `presence_penalty` is set to a value greater than 0, it
+            # indicates a preference for new tokens over those already
+            # present in the output.
+            # Verify that the penalized token ID exists in the output, while the
+            # non-penalized token ID does not.
+            assert penalized_token_id in output_token_ids[batch_idx]
+            assert non_penalized_token_id not in output_token_ids[batch_idx]
+        elif presence_penalty < 0:
+            # If `presence_penalty` is set to a value less than 0, it indicates
+            # a preference for existing tokens over new ones. Verify that the
+            # non-penalized token ID exists in the output, while the penalized
+            # token ID does not.
+            assert non_penalized_token_id in output_token_ids[batch_idx]
+            assert penalized_token_id not in output_token_ids[batch_idx]
+
+
+@pytest.mark.parametrize("device", CUDA_DEVICES)
+@pytest.mark.parametrize("batch_size", [1, 2, 32])
+@pytest.mark.parametrize("frequency_penalty", [-2.0, 2.0])
+def test_sampler_frequency_penalty(device: str, batch_size: int,
+                                   frequency_penalty: float):
+    """
+    Test to verify that if frequency penalty is enabled then tokens are
+    penalized as per their frequency of occurrence.
+    """
+    torch.set_default_device(device)
+    # Create fake logits where each token is assigned the same
+    # logit value.
+    fake_logits = _create_fake_logits(batch_size, VOCAB_SIZE)
+    sampling_metadata = _create_default_sampling_metadata(
+        NUM_OUTPUT_TOKENS, batch_size, VOCAB_SIZE, torch.device(device))
+    sampling_metadata.frequency_penalties = _create_penalty_tensor(
+        batch_size, frequency_penalty, torch.device(device))
+    output_token_ids, sorted_token_ids_in_output = \
+        _create_weighted_output_token_list(batch_size, VOCAB_SIZE)
+    sampling_metadata.output_token_ids = output_token_ids
+    sampling_metadata.no_penalties = False
+    sampler = Sampler()
+    sampler_output = sampler(fake_logits, sampling_metadata)
+    for batch_idx in range(batch_size):
+        logprobs_token_ids = sampler_output.logprob_token_ids[batch_idx]
+        non_penalized_token_id = logprobs_token_ids[0]
+        penalized_token_id = logprobs_token_ids[VOCAB_SIZE - 1]
+        distinct_sorted_token_ids_in_output = \
+            sorted_token_ids_in_output[batch_idx]
+        most_frequent_token_id = distinct_sorted_token_ids_in_output[
+            len(distinct_sorted_token_ids_in_output) - 1]
+        if frequency_penalty > 0:
+            # If `frequency_penalty` is set to > 0, it indicates
+            # a preference for new tokens over existing ones. Verify that the
+            # non-penalized token ID is not present in the output, while the
+            # most penalized token is the one that occurs most frequently in
+            # the output.
+            assert non_penalized_token_id \
+                not in distinct_sorted_token_ids_in_output
+            assert penalized_token_id == most_frequent_token_id
+        elif frequency_penalty < 0:
+            # If `frequency_penalty` is set to < 0, it indicates
+            # a preference for existing tokens over new ones. Verify that the
+            # non-penalized token ID is the one that occurs most frequently
+            # in the output, while the penalized token ID is one that has not
+            # yet appeared.
+            assert non_penalized_token_id == most_frequent_token_id
+            assert penalized_token_id \
+                not in distinct_sorted_token_ids_in_output
+
+
+@pytest.mark.parametrize("device", CUDA_DEVICES)
+@pytest.mark.parametrize("batch_size", [1, 2, 32])
+@pytest.mark.parametrize("repetition_penalty", [0.1, 1.9])
+def test_sampler_repetition_penalty(device: str, batch_size: int,
+                                    repetition_penalty: float):
+    """
+    Test to verify that when the repetition penalty is enabled, tokens 
+    are penalized based on their presence in the prompt or the existing
+    output.
+    """
+    torch.set_default_device(device)
+    # Create fake logits where each token is assigned the same
+    # logit value.
+    fake_logits = _create_fake_logits(batch_size, VOCAB_SIZE)
+    sampling_metadata = _create_default_sampling_metadata(
+        NUM_OUTPUT_TOKENS, batch_size, VOCAB_SIZE, torch.device(device))
+    sampling_metadata.repetition_penalties = _create_penalty_tensor(
+        batch_size, repetition_penalty, torch.device(device))
+    sampling_metadata.no_penalties = False
+    sampler = Sampler()
+    sampler_output = sampler(fake_logits, sampling_metadata)
+    for batch_idx in range(batch_size):
+        logprobs_token_ids = sampler_output.logprob_token_ids[batch_idx]
+        non_penalized_token_id = logprobs_token_ids[0]
+        penalized_token_id = logprobs_token_ids[VOCAB_SIZE - 1]
+        prompt_tokens = sampling_metadata.prompt_token_ids[
+            batch_idx][:].tolist()
+        output_tokens = sampling_metadata.output_token_ids[batch_idx]
+        if repetition_penalty > 1.0:
+            # If `repetition_penalty` > 1.0, verify that the non-penalized
+            # token ID has not been seen before, while the penalized token ID
+            # exists either in the prompt or the output.
+            assert (non_penalized_token_id not in prompt_tokens and \
+                non_penalized_token_id not in output_tokens)
+            assert (penalized_token_id  in prompt_tokens or \
+                penalized_token_id in output_tokens)
+        elif repetition_penalty < 1.0:
+            # If `repetition_penalty` < 1.0, verify that the penalized
+            # token ID has not been seen before, while the non-penalized
+            # token ID exists either in the prompt or the output.
+            assert (penalized_token_id not in prompt_tokens and \
+                penalized_token_id not in output_tokens)
+            assert (non_penalized_token_id  in prompt_tokens or \
+                non_penalized_token_id in output_tokens)