fix: kill_process_tree waits for the reap by default (#36589)

python/sglang/lang/backend/runtime_endpoint.py

@@ -443,7 +443,9 @@ class Runtime:
         from sglang.srt.utils import kill_process_tree
 
         if self.pid is not None:
-            kill_process_tree(self.pid)
+            # Note(kpham-sgl): __del__ routes here, so the reap wait has to stay
+            # off -- blocking inside GC stalls whichever thread is allocating.
+            kill_process_tree(self.pid, wait_timeout=None)
             self.pid = None
 
     def start_profile(self):

python/sglang/srt/managers/tokenizer_manager.py

@@ -3166,7 +3166,7 @@ class TokenizerManager(TokenizerControlMixin, TokenizerManagerScoreMixin):
         deadline = time.monotonic() + 15
         while time.monotonic() < deadline and collect_scheduler_processes():
             time.sleep(0.1)
-        kill_process_tree(os.getpid(), include_parent=True)
+        kill_process_tree(os.getpid(), include_parent=False, wait_timeout=60)
         sys.exit(0)
 
     def force_exit_handler(self):

python/sglang/srt/utils/common.py

@@ -2219,14 +2219,17 @@ def kill_process_tree(
     parent_pid,
     include_parent: bool = True,
     skip_pid: int = None,
-    wait_timeout: Optional[float] = None,
+    wait_timeout: Optional[float] = 60,
 ):
     """Kill the process and all its child processes.
 
     `wait_timeout` (seconds) blocks until every killed process is reaped and
-    raises `RuntimeError` on timeout; `None` is fire-and-forget. The
-    `parent_pid == os.getpid()` branch calls `sys.exit(0)` and cannot wait
-    for itself -- use `include_parent=False` if child reap must finish first.
+    raises `RuntimeError` on timeout. SIGKILL only queues the teardown, so
+    returning without waiting leaves the GPU context, the pinned host memory
+    and the ports held for seconds; pass `None` only where blocking is
+    unacceptable, such as a `__del__`. The `parent_pid == os.getpid()` branch
+    calls `sys.exit(0)` and cannot wait for itself -- use
+    `include_parent=False` if child reap must finish first.
     """
     logger.info(
         f"kill_process_tree called: parent_pid={parent_pid}, "
@@ -2239,10 +2242,10 @@ def kill_process_tree(
 
     try:
         itself = psutil.Process(parent_pid)
+        children = itself.children(recursive=True)
     except psutil.NoSuchProcess:
         return
 
-    children = itself.children(recursive=True)
     killed = []
     for child in children:
         if child.pid == skip_pid: