Crash the server correctly during error (#2231)

python/sglang/srt/managers/data_parallel_controller.py

@@ -15,9 +15,11 @@
 
 import logging
 import multiprocessing as mp
+import signal
 import threading
 from enum import Enum, auto
 
+import psutil
 import zmq
 
 from sglang.srt.managers.io_struct import (
@@ -26,13 +28,7 @@ from sglang.srt.managers.io_struct import (
 )
 from sglang.srt.managers.scheduler import run_scheduler_process
 from sglang.srt.server_args import PortArgs, ServerArgs
-from sglang.srt.utils import (
-    bind_port,
-    configure_logger,
-    get_zmq_socket,
-    kill_parent_process,
-    suppress_other_loggers,
-)
+from sglang.srt.utils import bind_port, configure_logger, get_zmq_socket
 from sglang.utils import get_exception_traceback
 
 logger = logging.getLogger(__name__)
@@ -235,7 +231,7 @@ def run_data_parallel_controller_process(
     pipe_writer,
 ):
     configure_logger(server_args)
-    suppress_other_loggers()
+    parent_process = psutil.Process().parent()
 
     try:
         controller = DataParallelController(server_args, port_args)
@@ -244,6 +240,6 @@ def run_data_parallel_controller_process(
         )
         controller.event_loop()
     except Exception:
-        msg = get_exception_traceback()
-        logger.error(msg)
-        kill_parent_process()
+        traceback = get_exception_traceback()
+        logger.error(f"DataParallelController hit an exception: {traceback}")
+        parent_process.send_signal(signal.SIGQUIT)

python/sglang/srt/managers/detokenizer_manager.py

@@ -15,9 +15,11 @@
 
 import dataclasses
 import logging
+import signal
 from collections import OrderedDict
 from typing import List, Union
 
+import psutil
 import zmq
 
 from sglang.srt.hf_transformers_utils import get_tokenizer
@@ -28,7 +30,7 @@ from sglang.srt.managers.io_struct import (
 )
 from sglang.srt.managers.schedule_batch import FINISH_MATCHED_STR, FINISH_MATCHED_TOKEN
 from sglang.srt.server_args import PortArgs, ServerArgs
-from sglang.srt.utils import configure_logger, get_zmq_socket, kill_parent_process
+from sglang.srt.utils import configure_logger, get_zmq_socket
 from sglang.utils import find_printable_text, get_exception_traceback
 
 logger = logging.getLogger(__name__)
@@ -193,11 +195,12 @@ def run_detokenizer_process(
     port_args: PortArgs,
 ):
     configure_logger(server_args)
+    parent_process = psutil.Process().parent()
 
     try:
         manager = DetokenizerManager(server_args, port_args)
         manager.event_loop()
     except Exception:
-        msg = get_exception_traceback()
-        logger.error(msg)
-        kill_parent_process()
+        traceback = get_exception_traceback()
+        logger.error(f"DetokenizerManager hit an exception: {traceback}")
+        parent_process.send_signal(signal.SIGQUIT)

python/sglang/srt/managers/scheduler.py

@@ -15,6 +15,7 @@
 
 import logging
 import os
+import signal
 import threading
 import time
 import warnings
@@ -23,6 +24,7 @@ from concurrent import futures
 from types import SimpleNamespace
 from typing import List, Optional
 
+import psutil
 import torch
 import zmq
 
@@ -73,7 +75,6 @@ from sglang.srt.utils import (
     crash_on_warnings,
     get_bool_env_var,
     get_zmq_socket,
-    kill_parent_process,
     set_gpu_proc_affinity,
     set_random_seed,
     suppress_other_loggers,
@@ -316,6 +317,7 @@ class Scheduler:
         self.watchdog_timeout = server_args.watchdog_timeout
         t = threading.Thread(target=self.watchdog_thread, daemon=True)
         t.start()
+        self.parent_process = psutil.Process().parent()
 
         # Init profiler
         if os.getenv("SGLANG_TORCH_PROFILER_DIR", "") == "":
@@ -359,7 +361,7 @@ class Scheduler:
                     self.watchdog_last_time = time.time()
             time.sleep(self.watchdog_timeout / 2)
 
-        kill_parent_process()
+        self.parent_process.send_signal(signal.SIGQUIT)
 
     @torch.no_grad()
     def event_loop_normal(self):
@@ -1423,6 +1425,7 @@ def run_scheduler_process(
         configure_logger(server_args, prefix=f" DP{dp_rank} TP{tp_rank}")
 
     suppress_other_loggers()
+    parent_process = psutil.Process().parent()
 
     try:
         scheduler = Scheduler(server_args, port_args, gpu_id, tp_rank, dp_rank)
@@ -1434,6 +1437,6 @@ def run_scheduler_process(
         else:
             scheduler.event_loop_normal()
     except Exception:
-        msg = get_exception_traceback()
-        logger.error(msg)
-        kill_parent_process()
+        traceback = get_exception_traceback()
+        logger.error(f"Scheduler hit an exception: {traceback}")
+        parent_process.send_signal(signal.SIGQUIT)

python/sglang/srt/managers/tokenizer_manager.py

@@ -58,7 +58,7 @@ from sglang.srt.managers.io_struct import (
 from sglang.srt.metrics.collector import TokenizerMetricsCollector
 from sglang.srt.sampling.sampling_params import SamplingParams
 from sglang.srt.server_args import PortArgs, ServerArgs
-from sglang.srt.utils import get_zmq_socket, kill_child_process
+from sglang.srt.utils import get_zmq_socket, kill_process_tree
 
 asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
 
@@ -532,7 +532,7 @@ class TokenizerManager:
             else:
                 break
 
-        kill_child_process(include_self=True)
+        kill_process_tree(os.getpid(), include_parent=True)
         sys.exit(0)
 
     async def handle_loop(self):

python/sglang/srt/managers/tp_worker_overlap_thread.py

@@ -15,16 +15,19 @@
 
 import dataclasses
 import logging
+import signal
 import threading
 from queue import Queue
 from typing import Optional
 
+import psutil
 import torch
 
 from sglang.srt.managers.io_struct import UpdateWeightReqInput
 from sglang.srt.managers.schedule_batch import ModelWorkerBatch
 from sglang.srt.managers.tp_worker import TpModelWorker
 from sglang.srt.server_args import ServerArgs
+from sglang.utils import get_exception_traceback
 
 logger = logging.getLogger(__name__)
 
@@ -70,6 +73,7 @@ class TpModelWorkerClient:
             target=self.forward_thread_func,
         )
         self.forward_thread.start()
+        self.parent_process = psutil.Process().parent()
 
     def get_worker_info(self):
         return self.worker.get_worker_info()
@@ -87,8 +91,13 @@ class TpModelWorkerClient:
         )
 
     def forward_thread_func(self):
-        with torch.cuda.stream(self.forward_stream):
-            self.forward_thread_func_()
+        try:
+            with torch.cuda.stream(self.forward_stream):
+                self.forward_thread_func_()
+        except Exception:
+            traceback = get_exception_traceback()
+            logger.error(f"TpModelWorkerClient hit an exception: {traceback}")
+            self.parent_process.send_signal(signal.SIGQUIT)
 
     @torch.no_grad()
     def forward_thread_func_(self):

python/sglang/srt/server.py

@@ -23,6 +23,8 @@ import json
 import logging
 import multiprocessing as mp
 import os
+import signal
+import sys
 import threading
 import time
 from http import HTTPStatus
@@ -79,7 +81,7 @@ from sglang.srt.utils import (
     configure_logger,
     delete_directory,
     is_port_available,
-    kill_child_process,
+    kill_process_tree,
     maybe_set_triton_cache_manager,
     prepare_model_and_tokenizer,
     set_prometheus_multiproc_dir,
@@ -572,6 +574,15 @@ def _set_envs_and_config(server_args: ServerArgs):
             "at https://docs.flashinfer.ai/installation.html.",
         )
 
+    # Register the signal handler.
+    # The child processes will send SIGQUIT to this process when any error happens
+    # This process then clean up the whole process tree
+    def sigquit_handler(signum, frame):
+        kill_process_tree(os.getpid())
+
+    signal.signal(signal.SIGQUIT, sigquit_handler)
+
+    # Set mp start method
     mp.set_start_method("spawn", force=True)
 
 
@@ -598,7 +609,7 @@ def _wait_and_warmup(server_args, pipe_finish_writer):
         if pipe_finish_writer is not None:
             pipe_finish_writer.send(last_traceback)
         logger.error(f"Initialization failed. warmup error: {last_traceback}")
-        kill_child_process(include_self=True)
+        kill_process_tree(os.getpid())
         return
 
     model_info = res.json()
@@ -631,7 +642,7 @@ def _wait_and_warmup(server_args, pipe_finish_writer):
         if pipe_finish_writer is not None:
             pipe_finish_writer.send(last_traceback)
         logger.error(f"Initialization failed. warmup error: {last_traceback}")
-        kill_child_process(include_self=True)
+        kill_process_tree(os.getpid())
         return
 
     # logger.info(f"{res.json()=}")
@@ -700,7 +711,7 @@ class Runtime:
 
     def shutdown(self):
         if self.pid is not None:
-            kill_child_process(self.pid, include_self=True)
+            kill_process_tree(self.pid)
             self.pid = None
 
     def cache_prefix(self, prefix: str):
@@ -924,7 +935,7 @@ class Engine:
             return ret
 
     def shutdown(self):
-        kill_child_process()
+        kill_process_tree(os.getpid(), include_parent=False)
 
     def get_tokenizer(self):
         global tokenizer_manager

python/sglang/srt/utils.py

@@ -443,26 +443,14 @@ def assert_pkg_version(pkg: str, min_version: str, message: str):
         )
 
 
-def kill_parent_process():
-    """Kill the parent process and all children of the parent process."""
-    current_process = psutil.Process()
-    parent_process = current_process.parent()
-    kill_child_process(
-        parent_process.pid, include_self=True, skip_pid=current_process.pid
-    )
-    try:
-        current_process.kill()
-    except psutil.NoSuchProcess:
-        pass
-
-
-def kill_child_process(pid=None, include_self=False, skip_pid=None):
-    """Kill the process and all its children process."""
-    if pid is None:
-        pid = os.getpid()
+def kill_process_tree(parent_pid, include_parent: bool = True, skip_pid: int = None):
+    """Kill the process and all its child processes."""
+    if parent_pid is None:
+        parent_pid = os.getpid()
+        include_parent = False
 
     try:
-        itself = psutil.Process(pid)
+        itself = psutil.Process(parent_pid)
     except psutil.NoSuchProcess:
         return
 
@@ -475,13 +463,13 @@ def kill_child_process(pid=None, include_self=False, skip_pid=None):
         except psutil.NoSuchProcess:
             pass
 
-    if include_self:
+    if include_parent:
         try:
             itself.kill()
 
             # Sometime processes cannot be killed with SIGKILL (e.g, PID=1 launched by kubernetes),
             # so we send an additional signal to kill them.
-            itself.send_signal(signal.SIGINT)
+            itself.send_signal(signal.SIGQUIT)
         except psutil.NoSuchProcess:
             pass