benchmark_serving.py

r"""Benchmark online serving throughput.

On the server side, run one of the following commands:
    vLLM OpenAI API server
    vllm serve <your_model> \
        --swap-space 16 \
        --disable-log-requests

    (TGI backend)
    ./launch_tgi_server.sh <your_model> <max_batch_total_tokens>

On the client side, run:
    python benchmarks/benchmark_serving.py \
        --backend <backend> \
        --model <your_model> \
        --dataset-name sharegpt \
        --dataset-path <path to dataset> \
        --request-rate <request_rate> \ # By default <request_rate> is inf
        --num-prompts <num_prompts> # By default <num_prompts> is 1000

    when using tgi backend, add
        --endpoint /generate_stream
    to the end of the command above.
"""
import argparse
import asyncio
import base64
import io
import json
import os
import random
import time
import warnings
from dataclasses import dataclass
from datetime import datetime
from typing import Any, AsyncGenerator, Collection, Dict, List, Optional, Tuple

import numpy as np
from backend_request_func import (ASYNC_REQUEST_FUNCS, RequestFuncInput,
                                  RequestFuncOutput)
from datasets import load_dataset
from PIL.Image import Image
from tqdm.asyncio import tqdm
from transformers import PreTrainedTokenizerBase

try:
    from vllm.transformers_utils.tokenizer import get_tokenizer
except ImportError:
    from backend_request_func import get_tokenizer

try:
    from vllm.utils import FlexibleArgumentParser
except ImportError:
    from argparse import ArgumentParser as FlexibleArgumentParser


@dataclass
class BenchmarkMetrics:
    completed: int
    total_input: int
    total_output: int
    request_throughput: float
    output_throughput: float
    total_token_throughput: float
    mean_ttft_ms: float
    median_ttft_ms: float
    std_ttft_ms: float
    percentiles_ttft_ms: List[Tuple[float, float]]
    mean_tpot_ms: float
    median_tpot_ms: float
    std_tpot_ms: float
    percentiles_tpot_ms: List[Tuple[float, float]]
    mean_itl_ms: float
    median_itl_ms: float
    std_itl_ms: float
    percentiles_itl_ms: List[Tuple[float, float]]
    # E2EL stands for end-to-end latency per request.
    # It is the time taken on the client side from sending
    # a request to receiving a complete response.
    mean_e2el_ms: float
    median_e2el_ms: float
    std_e2el_ms: float
    percentiles_e2el_ms: List[Tuple[float, float]]


def sample_sharegpt_requests(
    dataset_path: str,
    num_requests: int,
    tokenizer: PreTrainedTokenizerBase,
    fixed_output_len: Optional[int] = None,
) -> List[Tuple[str, int, int, None]]:
    # Load the dataset.
    with open(dataset_path, encoding='utf-8') as f:
        dataset = json.load(f)
    # Filter out the conversations with less than 2 turns.
    dataset = [data for data in dataset if len(data["conversations"]) >= 2]
    # Only keep the first two turns of each conversation.
    dataset = [(data["conversations"][0]["value"],
                data["conversations"][1]["value"]) for data in dataset]

    # Shuffle the dataset.
    random.shuffle(dataset)

    # Filter out sequences that are too long or too short
    filtered_dataset: List[Tuple[str, int, int]] = []
    for i in range(len(dataset)):
        if len(filtered_dataset) == num_requests:
            break

        # Tokenize the prompts and completions.
        prompt = dataset[i][0]
        prompt_token_ids = tokenizer(prompt).input_ids
        completion = dataset[i][1]
        completion_token_ids = tokenizer(completion).input_ids
        prompt_len = len(prompt_token_ids)
        output_len = len(completion_token_ids
                         ) if fixed_output_len is None else fixed_output_len
        if prompt_len < 4 or (fixed_output_len is None and output_len < 4):
            # Prune too short sequences.
            continue
        if prompt_len > 1024 or prompt_len + output_len > 2048:
            # Prune too long sequences.
            continue
        filtered_dataset.append((prompt, prompt_len, output_len, None))

    return filtered_dataset


def sample_sonnet_requests(
    dataset_path: str,
    num_requests: int,
    input_len: int,
    output_len: int,
    prefix_len: int,
    tokenizer: PreTrainedTokenizerBase,
) -> List[Tuple[str, str, int, int, None]]:
    assert (
        input_len > prefix_len
    ), "'args.sonnet-input-len' must be greater than 'args.prefix-input-len'."

    # Load the dataset.
    with open(dataset_path, encoding='utf-8') as f:
        poem_lines = f.readlines()

    # Tokenize the poem lines.
    poem_token_ids = tokenizer(poem_lines).input_ids
    average_poem_len = sum(
        len(token_ids) for token_ids in poem_token_ids) / len(poem_token_ids)

    # Base prefix for all requests.
    base_prompt = "Pick as many lines as you can from these poem lines:\n"
    base_message = [{
        "role": "user",
        "content": base_prompt,
    }]
    base_prompt_formatted = tokenizer.apply_chat_template(
        base_message, add_generation_prompt=True, tokenize=False)
    base_prompt_offset = len(tokenizer(base_prompt_formatted).input_ids)

    assert (
        input_len > base_prompt_offset
    ), f"Please set 'args.sonnet-input-len' higher than {base_prompt_offset}."
    num_input_lines = round(
        (input_len - base_prompt_offset) / average_poem_len)

    # First approximately `prefix_len` number of tokens in the
    # prompt are fixed poem lines.
    assert (
        prefix_len > base_prompt_offset
    ), f"Please set 'args.sonnet-prefix-len' higher than {base_prompt_offset}."

    num_prefix_lines = round(
        (prefix_len - base_prompt_offset) / average_poem_len)
    prefix_lines = poem_lines[:num_prefix_lines]

    # Sample the rest of lines per request.
    sampled_requests: List[Tuple[str, int, int]] = []
    for _ in range(num_requests):
        sampled_lines = "".join(
            prefix_lines +
            random.sample(poem_lines, num_input_lines - num_prefix_lines))

        prompt = f"{base_prompt}{sampled_lines}"
        message = [
            {
                "role": "user",
                "content": prompt,
            },
        ]
        prompt_formatted = tokenizer.apply_chat_template(
            message, add_generation_prompt=True, tokenize=False)
        prompt_len = len(tokenizer(prompt_formatted).input_ids)
        sampled_requests.append(
            (prompt, prompt_formatted, prompt_len, output_len, None))

    return sampled_requests


def sample_hf_requests(
    dataset_path: str,
    dataset_subset: str,
    dataset_split: str,
    num_requests: int,
    tokenizer: PreTrainedTokenizerBase,
    fixed_output_len: Optional[int] = None,
) -> List[Tuple[str, str, int, Optional[Dict[str, Collection[str]]]]]:
    dataset = load_dataset(dataset_path,
                           name=dataset_subset,
                           split=dataset_split,
                           streaming=True)
    assert "conversations" in dataset.features, (
        "HF Dataset must have 'conversations' column.")
    filtered_dataset = dataset.shuffle().filter(
        lambda x: len(x["conversations"]) >= 2)
    sampled_requests: List[Tuple[str, int, int, Dict[str,
                                                     Collection[str]]]] = []
    for data in filtered_dataset:
        if len(sampled_requests) == num_requests:
            break

        # Tokenize the prompts and completions.
        prompt = data["conversations"][0]["value"]
        prompt_token_ids = tokenizer(prompt).input_ids
        completion = data["conversations"][1]["value"]
        completion_token_ids = tokenizer(completion).input_ids
        prompt_len = len(prompt_token_ids)
        output_len = len(completion_token_ids
                         ) if fixed_output_len is None else fixed_output_len
        if fixed_output_len is None and (prompt_len < 4 or output_len < 4):
            # Prune too short sequences.
            continue
        if fixed_output_len is None and \
            (prompt_len > 1024 or prompt_len + output_len > 2048):
            # Prune too long sequences.
            continue

        if "image" in data and isinstance(data["image"], Image):
            image: Image = data["image"]
            image = image.convert("RGB")
            image_data = io.BytesIO()
            image.save(image_data, format='JPEG')
            image_base64 = base64.b64encode(
                image_data.getvalue()).decode("utf-8")
            mm_content = {
                "type": "image_url",
                "image_url": {
                    "url": f"data:image/jpeg;base64,{image_base64}"
                },
            }
        else:
            mm_content = None

        sampled_requests.append((prompt, prompt_len, output_len, mm_content))

    return sampled_requests


def sample_random_requests(
    prefix_len: int,
    input_len: int,
    output_len: int,
    num_prompts: int,
    range_ratio: float,
    tokenizer: PreTrainedTokenizerBase,
) -> List[Tuple[str, int, int]]:
    prefix_token_ids = np.random.randint(0,
                                         tokenizer.vocab_size,
                                         size=prefix_len).tolist()

    input_lens = np.random.randint(
        int(input_len * range_ratio),
        input_len + 1,
        size=num_prompts,
    )
    output_lens = np.random.randint(
        int(output_len * range_ratio),
        output_len + 1,
        size=num_prompts,
    )
    offsets = np.random.randint(0, tokenizer.vocab_size, size=num_prompts)
    input_requests = []
    for i in range(num_prompts):
        prompt = tokenizer.decode(prefix_token_ids +
                                  [(offsets[i] + i + j) % tokenizer.vocab_size
                                   for j in range(input_lens[i])])

        input_requests.append((prompt, int(prefix_len + input_lens[i]),
                               int(output_lens[i]), None))

    return input_requests


async def get_request(
    input_requests: List[Tuple[str, int, int]],
    request_rate: float,
) -> AsyncGenerator[Tuple[str, int, int], None]:
    input_requests = iter(input_requests)
    for request in input_requests:
        yield request

        if request_rate == float("inf"):
            # If the request rate is infinity, then we don't need to wait.
            continue

        # Sample the request interval from the exponential distribution.
        interval = np.random.exponential(1.0 / request_rate)
        # The next request will be sent after the interval.
        await asyncio.sleep(interval)


def calculate_metrics(
    input_requests: List[Tuple[str, int, int]],
    outputs: List[RequestFuncOutput],
    dur_s: float,
    tokenizer: PreTrainedTokenizerBase,
    selected_percentile_metrics: List[str],
    selected_percentiles: List[float],
) -> Tuple[BenchmarkMetrics, List[int]]:
    actual_output_lens: List[int] = []
    total_input = 0
    completed = 0
    itls: List[float] = []
    tpots: List[float] = []
    ttfts: List[float] = []
    e2els: List[float] = []
    for i in range(len(outputs)):
        if outputs[i].success:
            # We use the tokenizer to count the number of output tokens for all
            # serving backends instead of looking at len(outputs[i].itl) since
            # multiple output tokens may be bundled together
            # Note : this may inflate the output token count slightly
            output_len = len(
                tokenizer(outputs[i].generated_text,
                          add_special_tokens=False).input_ids)
            actual_output_lens.append(output_len)
            total_input += input_requests[i][1]
            if output_len > 1:
                tpots.append(
                    (outputs[i].latency - outputs[i].ttft) / (output_len - 1))
            itls += outputs[i].itl
            ttfts.append(outputs[i].ttft)
            e2els.append(outputs[i].latency)
            completed += 1
        else:
            actual_output_lens.append(0)

    if completed == 0:
        warnings.warn(
            "All requests failed. This is likely due to a misconfiguration "
            "on the benchmark arguments.",
            stacklevel=2)
    metrics = BenchmarkMetrics(
        completed=completed,
        total_input=total_input,
        total_output=sum(actual_output_lens),
        request_throughput=completed / dur_s,
        output_throughput=sum(actual_output_lens) / dur_s,
        total_token_throughput=(total_input + sum(actual_output_lens)) / dur_s,
        mean_ttft_ms=np.mean(ttfts or 0) *
        1000,  # ttfts is empty if streaming is not supported by backend
        std_ttft_ms=np.std(ttfts or 0) * 1000,
        median_ttft_ms=np.median(ttfts or 0) * 1000,
        percentiles_ttft_ms=[(p, np.percentile(ttfts or 0, p) * 1000)
                             for p in selected_percentiles],
        mean_tpot_ms=np.mean(tpots or 0) * 1000,
        std_tpot_ms=np.std(tpots or 0) * 1000,
        median_tpot_ms=np.median(tpots or 0) * 1000,
        percentiles_tpot_ms=[(p, np.percentile(tpots or 0, p) * 1000)
                             for p in selected_percentiles],
        mean_itl_ms=np.mean(itls or 0) * 1000,
        std_itl_ms=np.std(itls or 0) * 1000,
        median_itl_ms=np.median(itls or 0) * 1000,
        percentiles_itl_ms=[(p, np.percentile(itls or 0, p) * 1000)
                            for p in selected_percentiles],
        mean_e2el_ms=np.median(e2els or 0) * 1000,
        std_e2el_ms=np.std(e2els or 0) * 1000,
        median_e2el_ms=np.mean(e2els or 0) * 1000,
        percentiles_e2el_ms=[(p, np.percentile(e2els or 0, p) * 1000)
                             for p in selected_percentiles],
    )

    return metrics, actual_output_lens


async def benchmark(
    backend: str,
    api_url: str,
    base_url: str,
    model_id: str,
    tokenizer: PreTrainedTokenizerBase,
    input_requests: List[Tuple[str, int, int]],
    logprobs: Optional[int],
    best_of: int,
    use_beam_search: bool,
    request_rate: float,
    disable_tqdm: bool,
    profile: bool,
    selected_percentile_metrics: List[str],
    selected_percentiles: List[str],
):
    if backend in ASYNC_REQUEST_FUNCS:
        request_func = ASYNC_REQUEST_FUNCS[backend]
    else:
        raise ValueError(f"Unknown backend: {backend}")

    print("Starting initial single prompt test run...")
    test_prompt, test_prompt_len, test_output_len, test_mm_content = (
        input_requests[0])
    if backend != "openai-chat" and test_mm_content is not None:
        # multi-modal benchmark is only available on OpenAI Chat backend.
        raise ValueError(
            "Multi-modal content is only supported on 'openai-chat' backend.")
    test_input = RequestFuncInput(
        model=model_id,
        prompt=test_prompt,
        api_url=api_url,
        prompt_len=test_prompt_len,
        output_len=test_output_len,
        logprobs=logprobs,
        best_of=best_of,
        use_beam_search=use_beam_search,
        multi_modal_content=test_mm_content,
    )
    test_output = await request_func(request_func_input=test_input)
    if not test_output.success:
        raise ValueError(
            "Initial test run failed - Please make sure benchmark arguments "
            f"are correctly specified. Error: {test_output.error}")
    else:
        print("Initial test run completed. Starting main benchmark run...")

    if profile:
        print("Starting profiler...")
        profile_input = RequestFuncInput(
            model=model_id,
            prompt=test_prompt,
            api_url=base_url + "/start_profile",
            prompt_len=test_prompt_len,
            output_len=test_output_len,
            logprobs=logprobs,
            best_of=best_of,
            use_beam_search=use_beam_search,
            multi_modal_content=test_mm_content,
        )
        profile_output = await request_func(request_func_input=profile_input)
        if profile_output.success:
            print("Profiler started")

    print(f"Traffic request rate: {request_rate}")

    pbar = None if disable_tqdm else tqdm(total=len(input_requests))

    benchmark_start_time = time.perf_counter()
    tasks: List[asyncio.Task] = []
    async for request in get_request(input_requests, request_rate):
        prompt, prompt_len, output_len, mm_content = request
        request_func_input = RequestFuncInput(
            model=model_id,
            prompt=prompt,
            api_url=api_url,
            prompt_len=prompt_len,
            output_len=output_len,
            logprobs=logprobs,
            best_of=best_of,
            use_beam_search=use_beam_search,
            multi_modal_content=mm_content,
        )
        tasks.append(
            asyncio.create_task(
                request_func(request_func_input=request_func_input,
                             pbar=pbar)))
    outputs: List[RequestFuncOutput] = await asyncio.gather(*tasks)

    if profile:
        print("Stopping profiler...")
        profile_input = RequestFuncInput(
            model=model_id,
            prompt=test_prompt,
            api_url=base_url + "/stop_profile",
            prompt_len=test_prompt_len,
            output_len=test_output_len,
            logprobs=logprobs,
            best_of=best_of,
            use_beam_search=use_beam_search,
        )
        profile_output = await request_func(request_func_input=profile_input)
        if profile_output.success:
            print("Profiler stopped")

    if pbar is not None:
        pbar.close()

    benchmark_duration = time.perf_counter() - benchmark_start_time

    metrics, actual_output_lens = calculate_metrics(
        input_requests=input_requests,
        outputs=outputs,
        dur_s=benchmark_duration,
        tokenizer=tokenizer,
        selected_percentile_metrics=selected_percentile_metrics,
        selected_percentiles=selected_percentiles,
    )

    print("{s:{c}^{n}}".format(s=' Serving Benchmark Result ', n=50, c='='))
    print("{:<40} {:<10}".format("Successful requests:", metrics.completed))
    print("{:<40} {:<10.2f}".format("Benchmark duration (s):",
                                    benchmark_duration))
    print("{:<40} {:<10}".format("Total input tokens:", metrics.total_input))
    print("{:<40} {:<10}".format("Total generated tokens:",
                                 metrics.total_output))
    print("{:<40} {:<10.2f}".format("Request throughput (req/s):",
                                    metrics.request_throughput))
    print("{:<40} {:<10.2f}".format("Output token throughput (tok/s):",
                                    metrics.output_throughput))
    print("{:<40} {:<10.2f}".format("Total Token throughput (tok/s):",
                                    metrics.total_token_throughput))

    result = {
        "duration": benchmark_duration,
        "completed": metrics.completed,
        "total_input_tokens": metrics.total_input,
        "total_output_tokens": metrics.total_output,
        "request_throughput": metrics.request_throughput,
        "output_throughput": metrics.output_throughput,
        "total_token_throughput": metrics.total_token_throughput,
        "input_lens": [output.prompt_len for output in outputs],
        "output_lens": actual_output_lens,
        "ttfts": [output.ttft for output in outputs],
        "itls": [output.itl for output in outputs],
        "generated_texts": [output.generated_text for output in outputs],
        "errors": [output.error for output in outputs],
    }

    def process_one_metric(
        # E.g., "ttft"
        metric_attribute_name: str,
        # E.g., "TTFT"
        metric_name: str,
        # E.g., "Time to First Token"
        metric_header: str,
    ):
        # This function print and add statistics of the specified
        # metric.
        if metric_attribute_name not in selected_percentile_metrics:
            return
        print("{s:{c}^{n}}".format(s=metric_header, n=50, c='-'))
        print("{:<40} {:<10.2f}".format(
            f"Mean {metric_name} (ms):",
            getattr(metrics, f"mean_{metric_attribute_name}_ms")))
        print("{:<40} {:<10.2f}".format(
            f"Median {metric_name} (ms):",
            getattr(metrics, f"median_{metric_attribute_name}_ms")))
        result[f"mean_{metric_attribute_name}_ms"] = getattr(
            metrics, f"mean_{metric_attribute_name}_ms")
        result[f"median_{metric_attribute_name}_ms"] = getattr(
            metrics, f"median_{metric_attribute_name}_ms")
        result[f"std_{metric_attribute_name}_ms"] = getattr(
            metrics, f"std_{metric_attribute_name}_ms")
        for p, value in getattr(metrics,
                                f"percentiles_{metric_attribute_name}_ms"):
            p_word = str(int(p)) if int(p) == p else str(p)
            print("{:<40} {:<10.2f}".format(f"P{p_word} {metric_name} (ms):",
                                            value))
            result[f"p{p_word}_{metric_attribute_name}_ms"] = value

    process_one_metric("ttft", "TTFT", "Time to First Token")
    process_one_metric("tpot", "TPOT",
                       "Time per Output Token (excl. 1st token)")
    process_one_metric("itl", "ITL", "Inter-token Latency")
    process_one_metric("e2el", "E2EL", "End-to-end Latency")

    print("=" * 50)

    return result


def main(args: argparse.Namespace):
    print(args)
    random.seed(args.seed)
    np.random.seed(args.seed)

    backend = args.backend
    model_id = args.model
    tokenizer_id = args.tokenizer if args.tokenizer is not None else args.model

    if args.base_url is not None:
        api_url = f"{args.base_url}{args.endpoint}"
        base_url = f"{args.base_url}"
    else:
        api_url = f"http://{args.host}:{args.port}{args.endpoint}"
        base_url = f"http://{args.host}:{args.port}"

    tokenizer = get_tokenizer(tokenizer_id,
                              trust_remote_code=args.trust_remote_code)

    if args.dataset is not None:
        warnings.warn(
            "The '--dataset' argument will be deprecated in the next "
            "release. Please use '--dataset-name' and "
            "'--dataset-path' in the future runs.",
            stacklevel=2)
        input_requests = sample_sharegpt_requests(
            dataset_path=args.dataset,
            num_requests=args.num_prompts,
            tokenizer=tokenizer,
            fixed_output_len=args.sharegpt_output_len,
        )

    elif args.dataset_name == "sharegpt":
        input_requests = sample_sharegpt_requests(
            dataset_path=args.dataset_path,
            num_requests=args.num_prompts,
            tokenizer=tokenizer,
            fixed_output_len=args.sharegpt_output_len,
        )

    elif args.dataset_name == "sonnet":
        # Do not format the prompt, pass to message directly
        if args.backend == "openai-chat":
            input_requests = sample_sonnet_requests(
                dataset_path=args.dataset_path,
                num_requests=args.num_prompts,
                input_len=args.sonnet_input_len,
                output_len=args.sonnet_output_len,
                prefix_len=args.sonnet_prefix_len,
                tokenizer=tokenizer,
            )
            input_requests = [(prompt, prompt_len, output_len, None)
                              for prompt, prompt_formatted, prompt_len,
                              output_len, _ in input_requests]
        else:
            assert (
                tokenizer.chat_template or tokenizer.default_chat_template
            ), "Tokenizer/model must have chat template for sonnet dataset."
            input_requests = sample_sonnet_requests(
                dataset_path=args.dataset_path,
                num_requests=args.num_prompts,
                input_len=args.sonnet_input_len,
                output_len=args.sonnet_output_len,
                prefix_len=args.sonnet_prefix_len,
                tokenizer=tokenizer,
            )
            input_requests = [(prompt_formatted, prompt_len, output_len, None)
                              for prompt, prompt_formatted, prompt_len,
                              output_len, _ in input_requests]

    elif args.dataset_name == "hf":
        input_requests = sample_hf_requests(
            dataset_path=args.dataset_path,
            dataset_subset=args.hf_subset,
            dataset_split=args.hf_split,
            num_requests=args.num_prompts,
            tokenizer=tokenizer,
            fixed_output_len=args.hf_output_len,
        )

    elif args.dataset_name == "random":
        input_requests = sample_random_requests(
            prefix_len=args.random_prefix_len,
            input_len=args.random_input_len,
            output_len=args.random_output_len,
            num_prompts=args.num_prompts,
            range_ratio=args.random_range_ratio,
            tokenizer=tokenizer,
        )

    else:
        raise ValueError(f"Unknown dataset: {args.dataset_name}")

    benchmark_result = asyncio.run(
        benchmark(
            backend=backend,
            api_url=api_url,
            base_url=base_url,
            model_id=model_id,
            tokenizer=tokenizer,
            input_requests=input_requests,
            logprobs=args.logprobs,
            best_of=args.best_of,
            use_beam_search=args.use_beam_search,
            request_rate=args.request_rate,
            disable_tqdm=args.disable_tqdm,
            profile=args.profile,
            selected_percentile_metrics=args.percentile_metrics.split(","),
            selected_percentiles=[
                float(p) for p in args.metric_percentiles.split(",")
            ],
        ))

    # Save config and results to json
    if args.save_result:
        result_json: Dict[str, Any] = {}

        # Setup
        current_dt = datetime.now().strftime("%Y%m%d-%H%M%S")
        result_json["date"] = current_dt
        result_json["backend"] = backend
        result_json["model_id"] = model_id
        result_json["tokenizer_id"] = tokenizer_id
        result_json["best_of"] = args.best_of
        result_json["use_beam_search"] = args.use_beam_search
        result_json["num_prompts"] = args.num_prompts

        # Metadata
        if args.metadata:
            for item in args.metadata:
                if "=" in item:
                    kvstring = item.split("=")
                    result_json[kvstring[0].strip()] = kvstring[1].strip()
                else:
                    raise ValueError(
                        "Invalid metadata format. Please use KEY=VALUE format."
                    )

        # Traffic
        result_json["request_rate"] = (
            args.request_rate if args.request_rate < float("inf") else "inf")

        # Merge with benchmark result
        result_json = {**result_json, **benchmark_result}

        # Save to file
        base_model_id = model_id.split("/")[-1]
        file_name = f"{backend}-{args.request_rate}qps-{base_model_id}-{current_dt}.json"  #noqa
        if args.result_filename:
            file_name = args.result_filename
        if args.result_dir:
            file_name = os.path.join(args.result_dir, file_name)
        with open(file_name, "w", encoding='utf-8') as outfile:
            json.dump(result_json, outfile)


if __name__ == "__main__":
    parser = FlexibleArgumentParser(
        description="Benchmark the online serving throughput.")
    parser.add_argument(
        "--backend",
        type=str,
        default="vllm",
        choices=list(ASYNC_REQUEST_FUNCS.keys()),
    )
    parser.add_argument(
        "--base-url",
        type=str,
        default=None,
        help="Server or API base url if not using http host and port.",
    )
    parser.add_argument("--host", type=str, default="localhost")
    parser.add_argument("--port", type=int, default=8000)
    parser.add_argument(
        "--endpoint",
        type=str,
        default="/v1/completions",
        help="API endpoint.",
    )
    parser.add_argument(
        "--dataset",
        type=str,
        default=None,
        help="Path to the ShareGPT dataset, will be deprecated in the "
        "next release.",
    )
    parser.add_argument(
        "--dataset-name",
        type=str,
        default="sharegpt",
        choices=["sharegpt", "sonnet", "random", "hf"],
        help="Name of the dataset to benchmark on.",
    )
    parser.add_argument("--dataset-path",
                        type=str,
                        default=None,
                        help="Path to the sharegpt/sonnet dataset. "
                        "Or the huggingface dataset ID if using HF dataset.")
    parser.add_argument(
        "--model",
        type=str,
        required=True,
        help="Name of the model.",
    )
    parser.add_argument(
        "--tokenizer",
        type=str,
        help=
        "Name or path of the tokenizer, if not using the default tokenizer.",  # noqa: E501
    )
    parser.add_argument(
        "--best-of",
        type=int,
        default=1,
        help="Generates `best_of` sequences per prompt and "
        "returns the best one.",
    )
    parser.add_argument("--use-beam-search", action="store_true")
    parser.add_argument(
        "--num-prompts",
        type=int,
        default=1000,
        help="Number of prompts to process.",
    )
    parser.add_argument(
        "--logprobs",
        type=int,
        default=None,
        help=("Number of logprobs-per-token to compute & return as part of "
              "the request. If unspecified, then either (1) if beam search "
              "is disabled, no logprobs are computed & a single dummy "
              "logprob is returned for each token; or (2) if beam search "
              "is enabled 1 logprob per token is computed"),
    )
    parser.add_argument(
        "--request-rate",
        type=float,
        default=float("inf"),
        help="Number of requests per second. If this is inf, "
        "then all the requests are sent at time 0. "
        "Otherwise, we use Poisson process to synthesize "
        "the request arrival times.",
    )
    parser.add_argument("--seed", type=int, default=0)
    parser.add_argument(
        "--trust-remote-code",
        action="store_true",
        help="Trust remote code from huggingface",
    )
    parser.add_argument(
        "--disable-tqdm",
        action="store_true",
        help="Specify to disable tqdm progress bar.",
    )
    parser.add_argument(
        "--profile",
        action="store_true",
        help="Use Torch Profiler. The endpoint must be launched with "
        "VLLM_TORCH_PROFILER_DIR to enable profiler.",
    )
    parser.add_argument(
        "--save-result",
        action="store_true",
        help="Specify to save benchmark results to a json file",
    )
    parser.add_argument(
        "--metadata",
        metavar="KEY=VALUE",
        nargs="*",
        help="Key-value pairs (e.g, --metadata version=0.3.3 tp=1) "
        "for metadata of this run to be saved in the result JSON file "
        "for record keeping purposes.",
    )
    parser.add_argument(
        "--result-dir",
        type=str,
        default=None,
        help="Specify directory to save benchmark json results."
        "If not specified, results are saved in the current directory.",
    )
    parser.add_argument(
        "--result-filename",
        type=str,
        default=None,
        help="Specify the filename to save benchmark json results."
        "If not specified, results will be saved in "
        "{backend}-{args.request_rate}qps-{base_model_id}-{current_dt}.json"
        " format.",
    )
    parser.add_argument(
        "--percentile-metrics",
        type=str,
        default="ttft,tpot,itl",
        help="Comma-seperated list of selected metrics to report percentils. "
        "This argument specifies the metrics to report percentiles. "
        "Allowed metric names are \"ttft\", \"tpot\", \"itl\", \"e2el\". "
        "Default value is \"ttft,tpot,itl\".")
    parser.add_argument(
        "--metric-percentiles",
        type=str,
        default="99",
        help="Comma-seperated list of percentiles for selected metrics. "
        "To report 25-th, 50-th, and 75-th percentiles, use \"25,50,75\". "
        "Default value is \"99\". "
        "Use \"--percentile-metrics\" to select metrics.",
    )

    # group for dataset specific arguments
    sonnet_group = parser.add_argument_group("sonnet dataset options")
    sonnet_group.add_argument(
        "--sonnet-input-len",
        type=int,
        default=550,
        help=
        "Number of input tokens per request, used only for sonnet dataset.",
    )
    sonnet_group.add_argument(
        "--sonnet-output-len",
        type=int,
        default=150,
        help=
        "Number of output tokens per request, used only for sonnet dataset.",
    )
    sonnet_group.add_argument(
        "--sonnet-prefix-len",
        type=int,
        default=200,
        help=
        "Number of prefix tokens per request, used only for sonnet dataset.",
    )

    sharegpt_group = parser.add_argument_group("sharegpt dataset options")
    sharegpt_group.add_argument(
        "--sharegpt-output-len",
        type=int,
        default=None,
        help="Output length for each request. Overrides the output length "
        "from the ShareGPT dataset.")

    random_group = parser.add_argument_group("random dataset options")
    random_group.add_argument(
        "--random-input-len",
        type=int,
        default=1024,
        help=
        "Number of input tokens per request, used only for random sampling.",
    )
    random_group.add_argument(
        "--random-output-len",
        type=int,
        default=128,
        help=
        "Number of output tokens per request, used only for random sampling.",
    )
    random_group.add_argument(
        "--random-range-ratio",
        type=float,
        default=1.0,
        help="Range of sampled ratio of input/output length, "
        "used only for random sampling.",
    )
    random_group.add_argument(
        "--random-prefix-len",
        type=int,
        default=0,
        help="Number of fixed prefix tokens before random "
        " context. The length range of context in a random "
        " request is [random-prefix-len, "
        " random-prefix-len + random-prefix-len * random-range-ratio).")

    hf_group = parser.add_argument_group("hf dataset options")
    hf_group.add_argument("--hf-subset",
                          type=str,
                          default=None,
                          help="Subset of the HF dataset.")
    hf_group.add_argument("--hf-split",
                          type=str,
                          default=None,
                          help="Split of the HF dataset.")
    hf_group.add_argument(
        "--hf-output-len",
        type=int,
        default=None,
        help="Output length for each request. Overrides the output lengths "
        "from the sampled HF dataset.",
    )

    args = parser.parse_args()
    main(args)