[V1] [4/N] API Server: ZMQ/MP Utilities

docs/requirements-docs.txt

@@ -19,3 +19,4 @@ openai # Required by docs/source/serving/openai_compatible_server.md's vllm.entr
 fastapi # Required by docs/source/serving/openai_compatible_server.md's vllm.entrypoints.openai.cli_args
 partial-json-parser # Required by docs/source/serving/openai_compatible_server.md's vllm.entrypoints.openai.cli_args
 requests
+zmq

vllm/entrypoints/openai/api_server.py

@@ -68,7 +68,7 @@
 from vllm.logger import init_logger
 from vllm.usage.usage_lib import UsageContext
 from vllm.utils import (FlexibleArgumentParser, get_open_zmq_ipc_path,
-                        is_valid_ipv6_address, set_ulimit)
+                        is_valid_ipv6_address, kill_process_tree, set_ulimit)
 from vllm.version import __version__ as VLLM_VERSION
 
 TIMEOUT_KEEP_ALIVE = 5  # seconds
@@ -737,6 +737,15 @@ def signal_handler(*_) -> None:
 
     signal.signal(signal.SIGTERM, signal_handler)
 
+    # The child processes will send SIGQUIT to this process when
+    # any error happens. This process then clean up the whole tree.
+    # TODO(rob): move this into AsyncLLM.__init__ once we remove
+    # the context manager below.
+    def sigquit_handler(signum, frame):
+        kill_process_tree(os.getpid())
+
+    signal.signal(signal.SIGQUIT, sigquit_handler)
+
     async with build_async_engine_client(args) as engine_client:
         app = build_app(args)
 

vllm/executor/multiproc_worker_utils.py

@@ -1,5 +1,4 @@
 import asyncio
-import multiprocessing
 import os
 import sys
 import threading
@@ -13,10 +12,9 @@
 
 import torch
 
-import vllm.envs as envs
 from vllm.logger import init_logger
 from vllm.triton_utils.importing import HAS_TRITON
-from vllm.utils import cuda_is_initialized
+from vllm.utils import _check_multiproc_method, get_mp_context
 
 if HAS_TRITON:
     from vllm.triton_utils import maybe_set_triton_cache_manager
@@ -274,24 +272,6 @@ def write_with_prefix(s: str):
     file.write = write_with_prefix  # type: ignore[method-assign]
 
 
-def _check_multiproc_method():
-    if (cuda_is_initialized()
-            and os.environ.get("VLLM_WORKER_MULTIPROC_METHOD") != "spawn"):
-        logger.warning("CUDA was previously initialized. We must use "
-                       "the `spawn` multiprocessing start method. Setting "
-                       "VLLM_WORKER_MULTIPROC_METHOD to 'spawn'. "
-                       "See https://docs.vllm.ai/en/latest/getting_started/"
-                       "debugging.html#python-multiprocessing "
-                       "for more information.")
-        os.environ["VLLM_WORKER_MULTIPROC_METHOD"] = "spawn"
-
-
-def get_mp_context():
-    _check_multiproc_method()
-    mp_method = envs.VLLM_WORKER_MULTIPROC_METHOD
-    return multiprocessing.get_context(mp_method)
-
-
 def set_multiprocessing_worker_envs(parallel_config):
     """ Set up environment variables that should be used when there are workers
     in a multiprocessing environment. This should be called by the parent 

vllm/utils.py

@@ -10,6 +10,7 @@
 import importlib.util
 import inspect
 import ipaddress
+import multiprocessing
 import os
 import re
 import resource
@@ -20,6 +21,7 @@
 import tempfile
 import threading
 import time
+import traceback
 import uuid
 import warnings
 import weakref
@@ -29,8 +31,8 @@
 from dataclasses import dataclass, field
 from functools import lru_cache, partial, wraps
 from typing import (TYPE_CHECKING, Any, AsyncGenerator, Awaitable, Callable,
-                    Dict, Generator, Generic, Hashable, List, Literal,
-                    Optional, Tuple, Type, TypeVar, Union, overload)
+                    Dict, Generator, Generic, Hashable, Iterator, List,
+                    Literal, Optional, Tuple, Type, TypeVar, Union, overload)
 from uuid import uuid4
 
 import numpy as np
@@ -39,6 +41,8 @@
 import torch
 import torch.types
 import yaml
+import zmq
+import zmq.asyncio
 from packaging.version import Version
 from torch.library import Library
 from typing_extensions import ParamSpec, TypeIs, assert_never
@@ -1821,7 +1825,7 @@ def memory_profiling(
     result.non_kv_cache_memory_in_bytes = result.non_torch_increase_in_bytes + result.torch_peak_increase_in_bytes + result.weights_memory_in_bytes  # noqa
 
 
-# Adapted from: https://github.com/sgl-project/sglang/blob/f46f394f4d4dbe4aae85403dec006199b34d2840/python/sglang/srt/utils.py#L630 # noqa: E501Curre
+# Adapted from: https://github.com/sgl-project/sglang/blob/v0.4.1/python/sglang/srt/utils.py#L630 # noqa: E501
 def set_ulimit(target_soft_limit=65535):
     resource_type = resource.RLIMIT_NOFILE
     current_soft, current_hard = resource.getrlimit(resource_type)
@@ -1836,3 +1840,82 @@ def set_ulimit(target_soft_limit=65535):
                 "with error %s. This can cause fd limit errors like"
                 "`OSError: [Errno 24] Too many open files`. Consider "
                 "increasing with ulimit -n", current_soft, e)
+
+
+# Adapted from: https://github.com/sgl-project/sglang/blob/v0.4.1/python/sglang/utils.py#L28 # noqa: E501
+def get_exception_traceback():
+    etype, value, tb = sys.exc_info()
+    err_str = "".join(traceback.format_exception(etype, value, tb))
+    return err_str
+
+
+# Adapted from: https://github.com/sgl-project/sglang/blob/v0.4.1/python/sglang/srt/utils.py#L783 # noqa: E501
+def make_zmq_socket(
+    ctx: Union[zmq.asyncio.Context, zmq.Context],  # type: ignore[name-defined]
+    path: str,
+    type: Any,
+) -> Union[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(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
+    if total_mem > 32 and available_mem > 16:
+        buf_size = int(0.5 * 1024**3)  # 0.5GB in bytes
+    else:
+        buf_size = -1  # Use system default buffer size
+
+    if type == zmq.constants.PULL:
+        socket.setsockopt(zmq.constants.RCVHWM, 0)
+        socket.setsockopt(zmq.constants.RCVBUF, buf_size)
+        socket.connect(path)
+    elif type == zmq.constants.PUSH:
+        socket.setsockopt(zmq.constants.SNDHWM, 0)
+        socket.setsockopt(zmq.constants.SNDBUF, buf_size)
+        socket.bind(path)
+    else:
+        raise ValueError(f"Unknown Socket Type: {type}")
+
+    return socket
+
+
+@contextlib.contextmanager
+def zmq_socket_ctx(
+        path: str,
+        type: Any) -> Iterator[zmq.Socket]:  # type: ignore[name-defined]
+    """Context manager for a ZMQ socket"""
+
+    ctx = zmq.Context(io_threads=2)  # type: ignore[attr-defined]
+    try:
+        yield make_zmq_socket(ctx, path, type)
+
+    except KeyboardInterrupt:
+        logger.debug("Got Keyboard Interrupt.")
+
+    finally:
+        ctx.destroy(linger=0)
+
+
+def _check_multiproc_method():
+    if (cuda_is_initialized()
+            and os.environ.get("VLLM_WORKER_MULTIPROC_METHOD") != "spawn"):
+        logger.warning("CUDA was previously initialized. We must use "
+                       "the `spawn` multiprocessing start method. Setting "
+                       "VLLM_WORKER_MULTIPROC_METHOD to 'spawn'. "
+                       "See https://docs.vllm.ai/en/latest/getting_started/"
+                       "debugging.html#python-multiprocessing "
+                       "for more information.")
+        os.environ["VLLM_WORKER_MULTIPROC_METHOD"] = "spawn"
+
+
+def get_mp_context():
+    _check_multiproc_method()
+    mp_method = envs.VLLM_WORKER_MULTIPROC_METHOD
+    return multiprocessing.get_context(mp_method)

vllm/v1/engine/async_llm.py

@@ -78,11 +78,11 @@ def __init__(
 
         # EngineCore (starts the engine in background process).
         self.engine_core = EngineCoreClient.make_client(
-            vllm_config=vllm_config,
-            executor_class=executor_class,
-            usage_context=usage_context,
             multiprocess_mode=True,
             asyncio_mode=True,
+            vllm_config=vllm_config,
+            executor_class=executor_class,
+            log_stats=self.log_stats,
         )
 
         self.output_handler: Optional[asyncio.Task] = None