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vllm.logging_utils

Modules:

Name Description
dump_input
formatter
log_time

Provides a timeslice logging decorator

__all__ module-attribute 

__all__ = ['NewLineFormatter', 'logtime']

NewLineFormatter

Bases: Formatter

Adds logging prefix to newlines to align multi-line messages.

Source code in vllm/logging_utils/formatter.py 
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class NewLineFormatter(logging.Formatter):
    """Adds logging prefix to newlines to align multi-line messages."""

    def __init__(self, fmt, datefmt=None, style="%"):
        super().__init__(fmt, datefmt, style)

        self.use_relpath = envs.VLLM_LOGGING_LEVEL == "DEBUG"
        if self.use_relpath:
            self.root_dir = Path(__file__).resolve().parent.parent.parent

    def format(self, record):

        def shrink_path(relpath: Path) -> str:
            """
            Shortens a file path for logging display:
            - Removes leading 'vllm' folder if present.
            - If path starts with 'v1',
            keeps the first two and last two levels,
            collapsing the middle as '...'.
            - Otherwise, keeps the first and last two levels,
            collapsing the middle as '...'.
            - If the path is short, returns it as-is.
            - Examples:
            vllm/model_executor/layers/quantization/utils/fp8_utils.py ->
            model_executor/.../quantization/utils/fp8_utils.py
            vllm/model_executor/layers/quantization/awq.py ->
            model_executor/layers/quantization/awq.py
            vllm/v1/attention/backends/mla/common.py ->
            v1/attention/backends/mla/common.py

            Args:
                relpath (Path): The relative path to be shortened.
            Returns:
                str: The shortened path string for display.
            """
            parts = list(relpath.parts)
            new_parts = []
            if parts and parts[0] == "vllm":
                parts = parts[1:]
            if parts and parts[0] == "v1":
                new_parts += parts[:2]
                parts = parts[2:]
            elif parts:
                new_parts += parts[:1]
                parts = parts[1:]
            if len(parts) > 2:
                new_parts += ["..."] + parts[-2:]
            else:
                new_parts += parts
            return "/".join(new_parts)

        if self.use_relpath:
            abs_path = getattr(record, "pathname", None)
            if abs_path:
                try:
                    relpath = Path(abs_path).resolve().relative_to(
                        self.root_dir)
                except Exception:
                    relpath = Path(record.filename)
            else:
                relpath = Path(record.filename)
            record.fileinfo = shrink_path(relpath)
        else:
            record.fileinfo = record.filename

        msg = super().format(record)
        if record.message != "":
            parts = msg.split(record.message)
            msg = msg.replace("\n", "\r\n" + parts[0])
        return msg

root_dir instance-attribute 

root_dir = parent

use_relpath instance-attribute 

use_relpath = VLLM_LOGGING_LEVEL == 'DEBUG'

__init__ 

__init__(fmt, datefmt=None, style='%')
Source code in vllm/logging_utils/formatter.py 
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def __init__(self, fmt, datefmt=None, style="%"):
    super().__init__(fmt, datefmt, style)

    self.use_relpath = envs.VLLM_LOGGING_LEVEL == "DEBUG"
    if self.use_relpath:
        self.root_dir = Path(__file__).resolve().parent.parent.parent

format 

format(record)
Source code in vllm/logging_utils/formatter.py 
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def format(self, record):

    def shrink_path(relpath: Path) -> str:
        """
        Shortens a file path for logging display:
        - Removes leading 'vllm' folder if present.
        - If path starts with 'v1',
        keeps the first two and last two levels,
        collapsing the middle as '...'.
        - Otherwise, keeps the first and last two levels,
        collapsing the middle as '...'.
        - If the path is short, returns it as-is.
        - Examples:
        vllm/model_executor/layers/quantization/utils/fp8_utils.py ->
        model_executor/.../quantization/utils/fp8_utils.py
        vllm/model_executor/layers/quantization/awq.py ->
        model_executor/layers/quantization/awq.py
        vllm/v1/attention/backends/mla/common.py ->
        v1/attention/backends/mla/common.py

        Args:
            relpath (Path): The relative path to be shortened.
        Returns:
            str: The shortened path string for display.
        """
        parts = list(relpath.parts)
        new_parts = []
        if parts and parts[0] == "vllm":
            parts = parts[1:]
        if parts and parts[0] == "v1":
            new_parts += parts[:2]
            parts = parts[2:]
        elif parts:
            new_parts += parts[:1]
            parts = parts[1:]
        if len(parts) > 2:
            new_parts += ["..."] + parts[-2:]
        else:
            new_parts += parts
        return "/".join(new_parts)

    if self.use_relpath:
        abs_path = getattr(record, "pathname", None)
        if abs_path:
            try:
                relpath = Path(abs_path).resolve().relative_to(
                    self.root_dir)
            except Exception:
                relpath = Path(record.filename)
        else:
            relpath = Path(record.filename)
        record.fileinfo = shrink_path(relpath)
    else:
        record.fileinfo = record.filename

    msg = super().format(record)
    if record.message != "":
        parts = msg.split(record.message)
        msg = msg.replace("\n", "\r\n" + parts[0])
    return msg

logtime 

logtime(logger, msg=None)

Logs the execution time of the decorated function. Always place it beneath other decorators.

Source code in vllm/logging_utils/log_time.py 
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def logtime(logger, msg=None):
    """
    Logs the execution time of the decorated function.
    Always place it beneath other decorators.
    """

    def _inner(func):

        @functools.wraps(func)
        def _wrapper(*args, **kwargs):
            start = time.perf_counter()
            result = func(*args, **kwargs)
            elapsed = time.perf_counter() - start

            prefix = f"Function '{func.__module__}.{func.__qualname__}'" \
                if msg is None else msg
            logger.debug("%s: Elapsed time %.7f secs", prefix, elapsed)
            return result

        return _wrapper

    return _inner