sgl-project/sglang · error · ValueError

Unsupported socket type: {socket_type}

Error message

Unsupported socket type: {socket_type}

What it means

config_socket applies ZMQ send/recv buffer tuning per socket type; it handles PUB/SUB-ish, PUSH, PULL, DEALER/REQ/REP/PAIR patterns. Any other zmq socket type (e.g., XSUB, XPUB, STREAM, radio) hits the raise because no hwm/linger preset is defined for it.

Source

Thrown at python/sglang/srt/utils/network.py:264

        buf_size = -1

    def set_send_opt():
        socket.setsockopt(zmq.SNDHWM, 0)
        socket.setsockopt(zmq.SNDBUF, buf_size)

    def set_recv_opt():
        socket.setsockopt(zmq.RCVHWM, 0)
        socket.setsockopt(zmq.RCVBUF, buf_size)

    if socket_type == zmq.PUSH:
        set_send_opt()
    elif socket_type == zmq.PULL:
        set_recv_opt()
    elif socket_type in [zmq.DEALER, zmq.REQ, zmq.REP, zmq.PAIR]:
        set_send_opt()
        set_recv_opt()
    else:
        raise ValueError(f"Unsupported socket type: {socket_type}")


def get_local_ip_by_nic(interface: str = None) -> Optional[str]:
    if not (interface := interface or os.environ.get("SGLANG_LOCAL_IP_NIC", None)):
        return None
    try:
        import netifaces
    except ImportError as e:
        raise ImportError(
            "Environment variable SGLANG_LOCAL_IP_NIC requires package netifaces, please install it through 'pip install netifaces'"
        ) from e

    try:
        addresses = netifaces.ifaddresses(interface)
        if netifaces.AF_INET in addresses:
            for addr_info in addresses[netifaces.AF_INET]:
                ip = addr_info.get("addr")
                if ip and ip != "127.0.0.1" and ip != "0.0.0.0":

View on GitHub (pinned to 0132848349)

Solutions

1. Use one of the supported types (PUSH/PULL/DEALER/REQ/REP/PAIR/PUB/SUB) for custom sockets.
2. Create and configure the ZMQ socket manually with setsockopt instead of going through config_socket.
3. Contribute a branch for the new type with appropriate send/recv options.

Example fix

# before
sock = get_zmq_socket(ctx, zmq.XPUB, endpoint)

# after
sock = ctx.socket(zmq.XPUB)
sock.set(zmq.SNDHWM, 1000)
sock.bind(endpoint)

import zmq
SUPPORTED = {zmq.PUSH, zmq.PULL, zmq.PUB, zmq.SUB, zmq.DEALER, zmq.REQ, zmq.REP, zmq.PAIR}
assert socket_type in SUPPORTED, f"configure {socket_type} manually"

When it happens

Trigger: Calling config_socket (directly or via get_zmq_socket) with a socket type outside the supported set — e.g., zmq.XPUB for a custom broker.

Common situations: User code adding a custom ZMQ transport (proxy, monitor, XPUB/XSUB bus) routed through sglang's socket helper.

Related errors

• Unsupported socket type: {socket_type}
• Could not bind port {port} on any configured address family
• Failed to get server info. {error_data['error']['message']}
• Failed to get model info: {str(e)}
• Failed to edit image: {str(e)}

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/146ba86e79681d1f. Report an issue: GitHub.