fully non-blocking pipeline parallelism executor loop.

Signed-off-by: Yuxian Qiu <[email protected]>

Author: yuxianq

tensorrt_llm/_torch/distributed/communicator.py

@@ -803,9 +803,9 @@ def send(self, tensor: torch.Tensor, dest: Optional[int] = None):
             self.nccl_comm.send(tensor, dest)
             return
 
-        self.tensor_ready_event.record()
+        tensor = tensor.clone()
+        self.send_stream.wait_stream(torch.cuda.current_stream())
         with torch.cuda.stream(self.send_stream):
-            self.tensor_ready_event.wait()
             self.nccl_comm.send(tensor, dest)
 
     def recv(self, tensor: torch.Tensor, src: Optional[int] = None):

tensorrt_llm/_torch/pyexecutor/executor_request_queue.py

@@ -14,6 +14,7 @@
 from tensorrt_llm.mapping import CpType
 
 from ..distributed import Distributed
+from .hang_detector import HangDetector
 from .llm_request import (ExecutorRequest, LlmRequest,
                           executor_request_to_llm_request)
 
@@ -50,7 +51,7 @@ class ExecutorRequestQueue:
     def __init__(self, dist: Distributed, enable_attention_dp: bool,
                  max_batch_size: int, max_beam_width: int,
                  max_num_active_requests: int, enable_iter_perf_stats: bool,
-                 batch_wait_timeout_ms: float):
+                 batch_wait_timeout_ms: float, hang_detector: HangDetector):
         self.dist = dist
         self.request_queue: queue.Queue[RequestQueueItem] = queue.Queue()
         self.waiting_queue: deque[RequestQueueItem] = deque()
@@ -66,6 +67,7 @@ def __init__(self, dist: Distributed, enable_attention_dp: bool,
         self.active = True
         self.batch_wait_timeout_ms = batch_wait_timeout_ms
         self.send_requests_handler = None
+        self.hang_detector = hang_detector
 
         # State tracking
         self.num_fetch_requests = 0
@@ -303,7 +305,9 @@ def _fetch_and_process_requests(
                 self.request_accumulated.clear()
                 # Reset timeout to 0 to avoid hanging when no new requests are available
                 timeout = datetime.timedelta(0)
+            self.hang_detector.pause()
             new_requests.extend(self._get_from_request_queue(timeout))
+            self.hang_detector.checkpoint()
 
         # Broadcast requests and handle Python objects
         new_requests, py_request_objects = self._handle_request_broadcasting(
@@ -477,8 +481,10 @@ def _handle_request_broadcasting(self,
             # Preserve original `new_requests` on rank 0
             _ = self._broadcast_new_requests(new_requests, py_request_objects)
         else:
+            self.hang_detector.pause()
             new_requests, py_request_objects = self._broadcast_new_requests(
                 new_requests, py_request_objects)
+            self.hang_detector.checkpoint()
 
         return new_requests, py_request_objects
 
@@ -589,7 +595,8 @@ def _broadcast_new_requests(
 
         # Broadcast within first tp group before send/recv chain to other tp groups
         if self.dist.tp_size > 1 and self.dist.is_first_pp_rank:
-            payloads = self.dist.tp_broadcast(payloads, root=0)
+            with nvtx_range("tp_broadcast_requests"):
+                payloads = self.dist.tp_broadcast(payloads, root=0)
 
         # Tag for communication
         tag = self.dist.pp_size  # Use pp_size as tag to avoid conflicts

tensorrt_llm/_torch/pyexecutor/hang_detector.py

@@ -0,0 +1,85 @@
+import asyncio
+import sys
+import threading
+import traceback
+from typing import Callable, Optional
+
+from tensorrt_llm.logger import logger
+
+
+class HangDetector:
+    def __init__(
+        self, timeout: Optional[int] = None, on_detected: Optional[Callable[[], None]] = None
+    ):
+        self.timeout = timeout or 60
+        self.on_detected = on_detected or (lambda: None)
+        self.task = None
+        self.loop = None
+        self.loop_thread = None
+        self.lock = threading.Lock()
+        self.active = False
+        self._detected = False
+
+    def start(self):
+        """Start monitoring for hangs"""
+
+        def run_loop():
+            asyncio.set_event_loop(self.loop)
+            self.loop.run_forever()
+
+        self.active = True
+        self.loop = asyncio.new_event_loop()
+        self.loop_thread = threading.Thread(target=run_loop, daemon=True, name="hang_detector_loop")
+        self.loop_thread.start()
+
+    async def _detect_hang(self):
+        await asyncio.sleep(self.timeout)
+        with self.lock:
+            self._detected = True
+            logger.error(f"Hang detected after {self.timeout} seconds.")
+            self.print_all_stacks()
+            self.on_detected()
+
+    def print_all_stacks(self):
+        """Print stack traces for all threads"""
+        for thread_id, frame in sys._current_frames().items():
+            logger.error(
+                f"Thread {thread_id} stack trace:\n" + "".join(traceback.format_stack(frame))
+            )
+
+    def detected(self):
+        """Return True if hang is detected"""
+        with self.lock:
+            return self._detected
+
+    def checkpoint(self):
+        """Call this periodically in your code"""
+        self.pause()
+        if self.active:
+            self.task = asyncio.run_coroutine_threadsafe(self._detect_hang(), self.loop)
+
+    def pause(self):
+        """Pause monitoring"""
+        if self.task is not None and not self.task.done():
+            self.task.cancel()
+            self.task = None
+
+    def stop(self):
+        """Stop monitoring"""
+        self.active = False
+        self.pause()
+        if self.loop is not None:
+            # Cancel all pending tasks before stopping the loop
+            def cancel_all_tasks():
+                for task in asyncio.all_tasks(self.loop):
+                    if not task.done():
+                        task.cancel()
+                self.loop.call_soon(self.loop.stop)
+
+            self.loop.call_soon_threadsafe(cancel_all_tasks)
+
+            if self.loop_thread is not None and self.loop_thread.is_alive():
+                self.loop_thread.join()
+
+            self.loop = None
+            self.loop_thread = None