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vllm.utils.network_utils

get_open_port

get_open_port() -> int

Get an open port for the vLLM process to listen on. An edge case to handle, is when we run data parallel, we need to avoid ports that are potentially used by the data parallel master process. Right now we reserve 10 ports for the data parallel master process. Currently it uses 2 ports.

Source code in vllm/utils/network_utils.py
def get_open_port() -> int:
    """
    Get an open port for the vLLM process to listen on.
    An edge case to handle, is when we run data parallel,
    we need to avoid ports that are potentially used by
    the data parallel master process.
    Right now we reserve 10 ports for the data parallel master
    process. Currently it uses 2 ports.
    """
    if "VLLM_DP_MASTER_PORT" in os.environ:
        dp_master_port = envs.VLLM_DP_MASTER_PORT
        reserved_port_range = range(dp_master_port, dp_master_port + 10)
        while True:
            candidate_port = _get_open_port()
            if candidate_port not in reserved_port_range:
                return candidate_port
    return _get_open_port()

get_open_ports_list

get_open_ports_list(count: int = 5) -> list[int]

Get a list of open ports.

Source code in vllm/utils/network_utils.py
def get_open_ports_list(count: int = 5) -> list[int]:
    """Get a list of open ports."""
    ports = set[int]()
    while len(ports) < count:
        ports.add(get_open_port())
    return list(ports)

make_zmq_path

make_zmq_path(
    scheme: str, host: str, port: int | None = None
) -> str

Make a ZMQ path from its parts.

Parameters:

Name Type Description Default
scheme str

The ZMQ transport scheme (e.g. tcp, ipc, inproc).

required
host str

The host - can be an IPv4 address, IPv6 address, or hostname.

required
port int | None

Optional port number, only used for TCP sockets.

None

Returns:

Type Description
str

A properly formatted ZMQ path string.

Source code in vllm/utils/network_utils.py
def make_zmq_path(scheme: str, host: str, port: int | None = None) -> str:
    """Make a ZMQ path from its parts.

    Args:
        scheme: The ZMQ transport scheme (e.g. tcp, ipc, inproc).
        host: The host - can be an IPv4 address, IPv6 address, or hostname.
        port: Optional port number, only used for TCP sockets.

    Returns:
        A properly formatted ZMQ path string.
    """
    if port is None:
        return f"{scheme}://{host}"
    if is_valid_ipv6_address(host):
        return f"{scheme}://[{host}]:{port}"
    return f"{scheme}://{host}:{port}"

make_zmq_socket

make_zmq_socket(
    ctx: Context | Context,
    path: str,
    socket_type: Any,
    bind: bool | None = None,
    identity: bytes | None = None,
    linger: int | None = None,
) -> Socket | Socket

Make a ZMQ socket with the proper bind/connect semantics.

Source code in vllm/utils/network_utils.py
def make_zmq_socket(
    ctx: zmq.asyncio.Context | zmq.Context,  # type: ignore[name-defined]
    path: str,
    socket_type: Any,
    bind: bool | None = None,
    identity: bytes | None = None,
    linger: int | None = None,
) -> zmq.Socket | zmq.asyncio.Socket:  # type: ignore[name-defined]
    """Make a ZMQ socket with the proper bind/connect semantics."""

    mem = psutil.virtual_memory()
    socket = ctx.socket(socket_type)

    # Calculate buffer size based on system memory
    total_mem = mem.total / 1024**3
    available_mem = mem.available / 1024**3
    # For systems with substantial memory (>32GB total, >16GB available):
    # - Set a large 0.5GB buffer to improve throughput
    # For systems with less memory:
    # - Use system default (-1) to avoid excessive memory consumption
    buf_size = int(0.5 * 1024**3) if total_mem > 32 and available_mem > 16 else -1

    if bind is None:
        bind = socket_type not in (zmq.PUSH, zmq.SUB, zmq.XSUB)

    if socket_type in (zmq.PULL, zmq.DEALER, zmq.ROUTER):
        socket.setsockopt(zmq.RCVHWM, 0)
        socket.setsockopt(zmq.RCVBUF, buf_size)

    if socket_type in (zmq.PUSH, zmq.DEALER, zmq.ROUTER):
        socket.setsockopt(zmq.SNDHWM, 0)
        socket.setsockopt(zmq.SNDBUF, buf_size)

    if identity is not None:
        socket.setsockopt(zmq.IDENTITY, identity)

    if linger is not None:
        socket.setsockopt(zmq.LINGER, linger)

    if socket_type == zmq.XPUB:
        socket.setsockopt(zmq.XPUB_VERBOSE, True)

    # Determine if the path is a TCP socket with an IPv6 address.
    # Enable IPv6 on the zmq socket if so.
    scheme, host, _ = split_zmq_path(path)
    if scheme == "tcp" and is_valid_ipv6_address(host):
        socket.setsockopt(zmq.IPV6, 1)

    if bind:
        socket.bind(path)
    else:
        socket.connect(path)

    return socket

split_zmq_path

split_zmq_path(path: str) -> tuple[str, str, str]

Split a zmq path into its parts.

Source code in vllm/utils/network_utils.py
def split_zmq_path(path: str) -> tuple[str, str, str]:
    """Split a zmq path into its parts."""
    parsed = parse_url(path)
    if not parsed.scheme:
        raise ValueError(f"Invalid zmq path: {path}")

    scheme = parsed.scheme
    host = parsed.hostname or ""
    port = str(parsed.port or "")
    if host.startswith("[") and host.endswith("]"):
        host = host[1:-1]  # Remove brackets for IPv6 address

    if scheme == "tcp" and not all((host, port)):
        # The host and port fields are required for tcp
        raise ValueError(f"Invalid zmq path: {path}")

    if scheme != "tcp" and port:
        # port only makes sense with tcp
        raise ValueError(f"Invalid zmq path: {path}")

    return scheme, host, port

zmq_socket_ctx

zmq_socket_ctx(
    path: str,
    socket_type: Any,
    bind: bool | None = None,
    linger: int = 0,
    identity: bytes | None = None,
) -> Iterator[Socket]

Context manager for a ZMQ socket

Source code in vllm/utils/network_utils.py
@contextlib.contextmanager
def zmq_socket_ctx(
    path: str,
    socket_type: Any,
    bind: bool | None = None,
    linger: int = 0,
    identity: bytes | None = None,
) -> Iterator[zmq.Socket]:
    """Context manager for a ZMQ socket"""

    ctx = zmq.Context()  # type: ignore[attr-defined]
    try:
        yield make_zmq_socket(ctx, path, socket_type, bind=bind, identity=identity)
    except KeyboardInterrupt:
        logger.debug("Got Keyboard Interrupt.")

    finally:
        ctx.destroy(linger=linger)