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1 # SPDX-License-Identifier: Apache-2.0
2 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
3 import asyncio
4 import os
5 import threading
6 import time
7 import traceback
8 from typing import cast
9
10 import openai # use the official client for correctness check
11 import pytest
12 import pytest_asyncio
13 import requests
14
15 from tests.utils import RemoteOpenAIServer
16 from tests.v1.utils import check_request_balancing
17 from vllm.platforms import current_platform
18
19 MODEL_NAME = "ibm-research/PowerMoE-3b"
20
21 # Number of data parallel ranks for multi-node internal LB testing
22 DP_SIZE = int(os.getenv("DP_SIZE", "2"))
23 # Default tensor parallel size to use
24 TP_SIZE = int(os.getenv("TP_SIZE", "1"))
25
26 # Number of nodes to simulate
27 NUM_NODES = 2
28
29
30 async def _make_completion_request(
31 client: openai.AsyncOpenAI,
32 model_name: str,
33 ) -> openai.types.Completion:
34 """Make a single completion request and validate the response.
35
36 Uses temperature=1.0 to ensure diverse outputs across concurrent
37 requests for realistic load balancer testing.
38 """
39 completion = await client.completions.create(
40 model=model_name,
41 prompt="Hello, my name is",
42 max_tokens=5,
43 temperature=1.0,
44 )
45
46 assert completion.id is not None, (
47 f"Expected non-None completion id. usage={completion.usage!r}"
48 )
49 assert completion.choices is not None and len(completion.choices) == 1, (
50 f"Expected 1 choice, got "
51 f"{len(completion.choices) if completion.choices else 'None'}"
52 )
53
54 choice = completion.choices[0]
55 # With temperature=1.0, the model may emit a stop token immediately,
56 # producing empty text with finish_reason='stop'. This is valid
57 # model behavior - the test's purpose is load balancing, not output
58 # quality.
59 assert choice.finish_reason in ("length", "stop"), (
60 f"Expected finish_reason 'length' or 'stop', "
61 f"got {choice.finish_reason!r}. text={choice.text!r}"
62 )
63 if choice.finish_reason == "length":
64 assert len(choice.text) >= 1, (
65 f"Expected non-empty text with finish_reason='length', got {choice.text!r}"
66 )
67
68 assert completion.usage.prompt_tokens > 0, (
69 f"Expected positive prompt_tokens, got {completion.usage.prompt_tokens}"
70 )
71 assert completion.usage.total_tokens > 0, (
72 f"Expected positive total_tokens, got {completion.usage.total_tokens}"
73 )
74 return completion
75
76
77 async def _run_request_bursts(
78 client: openai.AsyncOpenAI,
79 model_name: str,
80 num_requests: int = 200,
81 num_bursts: int = 2,
82 ):
83 """Send multiple bursts of completion requests and validate all succeed."""
84 for burst in range(num_bursts):
85 all_tasks = []
86 for _ in range(num_requests):
87 all_tasks.append(
88 asyncio.create_task(_make_completion_request(client, model_name))
89 )
90 await asyncio.sleep(0.01)
91
92 results = await asyncio.gather(*all_tasks, return_exceptions=True)
93 assert len(results) == num_requests, (
94 f"Burst {burst}: expected {num_requests} results, got {len(results)}"
95 )
96
97 for result in results:
98 if isinstance(result, BaseException):
99 raise result
100
101 assert all(completion is not None for completion in results), (
102 f"Burst {burst}: some completions were None"
103 )
104
105 await asyncio.sleep(0.5)
106
107
108 class MultinodeInternalLBServerManager:
109 """Manages multi-node data parallel vLLM server instances for internal
110 load balancer testing using --headless mode."""
111
112 def __init__(
113 self,
114 model_name: str,
115 dp_size: int,
116 api_server_count: int,
117 base_server_args: list,
118 dp_per_node: int = 1,
119 tp_size: int = TP_SIZE,
120 ):
121 self.model_name = model_name
122 self.dp_size = dp_size
123 self.dp_per_node = dp_per_node
124 self.tp_size = tp_size
125 self.api_server_count = api_server_count
126 self.base_server_args = base_server_args
127 self.servers: list[tuple[RemoteOpenAIServer, list[str]] | None] = [None] * (
128 dp_size // dp_per_node
129 )
130 self.server_threads: list[threading.Thread] = []
131
132 def __enter__(self) -> list[tuple[RemoteOpenAIServer, list[str]]]:
133 """Start all server instances for multi-node internal LB mode."""
134 for server_idx, rank in enumerate(range(0, self.dp_size, self.dp_per_node)):
135 # Create server args for this specific rank
136 server_args = self.base_server_args.copy()
137
138 if rank == 0:
139 # Head node - runs API server and first DP rank
140 server_args.extend(
141 [
142 "--data-parallel-size",
143 str(self.dp_size),
144 "--data-parallel-size-local",
145 str(self.dp_per_node),
146 "--tensor-parallel-size",
147 str(self.tp_size),
148 "--port",
149 "8000", # Single endpoint for all requests
150 "--api-server-count",
151 str(self.api_server_count),
152 "--data-parallel-address",
153 "127.0.0.1",
154 "--data-parallel-rpc-port",
155 "13345",
156 ]
157 )
158 else:
159 # Secondary nodes - run in headless mode
160 server_args.extend(
161 [
162 "--headless",
163 "--data-parallel-size",
164 str(self.dp_size),
165 "--data-parallel-size-local",
166 str(self.dp_per_node),
167 "--data-parallel-start-rank",
168 str(rank),
169 "--tensor-parallel-size",
170 str(self.tp_size),
171 "--data-parallel-address",
172 "127.0.0.1",
173 "--data-parallel-rpc-port",
174 "13345",
175 ]
176 )
177
178 # Use a thread to start each server to allow parallel initialization
179 def start_server(sidx: int, r: int, sargs: list[str]):
180 gpus_per_node = self.tp_size * self.dp_per_node
181 try:
182 # Start the server
183 server = RemoteOpenAIServer(
184 self.model_name,
185 sargs,
186 auto_port=False,
187 max_wait_seconds=int(
188 os.getenv("VLLM_ENGINE_READY_TIMEOUT_S", "480")
189 ),
190 env_dict={
191 "VLLM_SERVER_DEV_MODE": "1",
192 current_platform.device_control_env_var: ",".join(
193 str(current_platform.device_id_to_physical_device_id(i))
194 for i in range(r, r + gpus_per_node)
195 ),
196 },
197 )
198 server.__enter__()
199 if r == 0:
200 print(
201 f"Head node (rank {r}) started successfully with "
202 f"{self.api_server_count} API servers"
203 )
204 else:
205 print(f"Headless node (rank {r}) started successfully")
206 self.servers[sidx] = (server, sargs)
207 except Exception as e:
208 print(f"Failed to start server rank {r}: {e}")
209 traceback.print_exc()
210 raise
211
212 thread = threading.Thread(
213 target=start_server, args=(server_idx, rank, server_args)
214 )
215 thread.start()
216
217 self.server_threads.append(thread)
218
219 # Wait for all servers to start
220 for thread in self.server_threads:
221 thread.join()
222
223 # Give servers additional time to fully initialize and coordinate
224 time.sleep(3)
225
226 if not all(self.servers):
227 raise Exception("Servers failed to start")
228
229 return cast(list[tuple[RemoteOpenAIServer, list[str]]], self.servers)
230
231 def __exit__(self, exc_type, exc_val, exc_tb):
232 """Stop all server instances."""
233 servers = [entry[0] for entry in self.servers if entry is not None]
234 self.servers.clear()
235 try:
236 RemoteOpenAIServer.shutdown_many(servers)
237 except Exception as e:
238 print(f"Error stopping servers: {e}")
239 traceback.print_exc()
240
241
242 class APIOnlyServerManager:
243 """Manages API-only server (Node 0) and headless engines server (Node 1)
244 for testing separated API server and engine configuration."""
245
246 def __init__(
247 self,
248 model_name: str,
249 dp_size: int,
250 api_server_count: int,
251 base_server_args: list,
252 tp_size: int = TP_SIZE,
253 ):
254 self.model_name = model_name
255 self.dp_size = dp_size
256 self.tp_size = tp_size
257 self.api_server_count = api_server_count
258 self.base_server_args = base_server_args
259 self.servers: list[tuple[RemoteOpenAIServer, list[str]] | None] = [None] * 2
260 self.server_threads: list[threading.Thread] = []
261
262 def __enter__(self) -> list[tuple[RemoteOpenAIServer, list[str]]]:
263 """Start API-only server and headless engines server."""
264 # Start API-only server (Node 0) - no engines, only API server
265 api_server_args = self.base_server_args.copy()
266 api_server_args.extend(
267 [
268 "--data-parallel-size",
269 str(self.dp_size),
270 "--data-parallel-size-local",
271 "0", # No engines on this node
272 "--tensor-parallel-size",
273 str(self.tp_size),
274 "--port",
275 "8000",
276 "--api-server-count",
277 str(self.api_server_count),
278 "--data-parallel-address",
279 "127.0.0.1",
280 "--data-parallel-rpc-port",
281 "13345",
282 ]
283 )
284
285 # Start headless engines server (Node 1) - all engines, no API server
286 engines_server_args = self.base_server_args.copy()
287 engines_server_args.extend(
288 [
289 "--headless",
290 "--data-parallel-size",
291 str(self.dp_size),
292 "--data-parallel-size-local",
293 str(self.dp_size), # All engines on this node
294 "--tensor-parallel-size",
295 str(self.tp_size),
296 "--data-parallel-address",
297 "127.0.0.1",
298 "--data-parallel-rpc-port",
299 "13345",
300 ]
301 )
302
303 # Use threads to start both servers in parallel
304 def start_api_server():
305 try:
306 server = RemoteOpenAIServer(
307 self.model_name,
308 api_server_args,
309 auto_port=False,
310 env_dict={
311 "VLLM_SERVER_DEV_MODE": "1",
312 # No GPUs needed for API-only server
313 },
314 )
315 server.__enter__()
316 print(
317 f"API-only server started successfully with "
318 f"{self.api_server_count} API servers"
319 )
320 self.servers[0] = (server, api_server_args)
321 except Exception as e:
322 print(f"Failed to start API-only server: {e}")
323 raise
324
325 def start_engines_server():
326 try:
327 server = RemoteOpenAIServer(
328 self.model_name,
329 engines_server_args,
330 auto_port=False,
331 env_dict={
332 current_platform.device_control_env_var: ",".join(
333 str(current_platform.device_id_to_physical_device_id(i))
334 for i in range(self.dp_size * self.tp_size)
335 ),
336 },
337 )
338 server.__enter__()
339 print(
340 f"Headless engines server started successfully with "
341 f"{self.dp_size} engines"
342 )
343 self.servers[1] = (server, engines_server_args)
344 except Exception as e:
345 print(f"Failed to start headless engines server: {e}")
346 raise
347
348 # Start API server first
349 api_thread = threading.Thread(target=start_api_server)
350 api_thread.start()
351 self.server_threads.append(api_thread)
352
353 # Start engines server second
354 engines_thread = threading.Thread(target=start_engines_server)
355 engines_thread.start()
356 self.server_threads.append(engines_thread)
357
358 # Wait for both servers to start
359 for thread in self.server_threads:
360 thread.join()
361
362 # Give servers additional time to fully initialize and coordinate
363 time.sleep(3)
364
365 if not all(self.servers):
366 raise Exception("Both servers failed to start")
367
368 return cast(list[tuple[RemoteOpenAIServer, list[str]]], self.servers)
369
370 def __exit__(self, exc_type, exc_val, exc_tb):
371 """Stop both server instances."""
372 servers = [entry[0] for entry in self.servers if entry is not None]
373 self.servers.clear()
374 try:
375 RemoteOpenAIServer.shutdown_many(servers)
376 except Exception as e:
377 print(f"Error stopping servers: {e}")
378 traceback.print_exc()
379
380
381 @pytest.fixture(scope="module")
382 def default_server_args():
383 return [
384 # use half precision for speed and memory savings in CI environment
385 "--dtype",
386 "bfloat16",
387 "--max-model-len",
388 "2048",
389 "--max-num-seqs",
390 "128",
391 "--enforce-eager",
392 ]
393
394
395 @pytest.fixture(scope="module", params=[1, 4])
396 def server_manager(request, default_server_args):
397 api_server_count = request.param
398 server_manager = MultinodeInternalLBServerManager(
399 MODEL_NAME,
400 DP_SIZE,
401 api_server_count,
402 default_server_args,
403 DP_SIZE // NUM_NODES,
404 TP_SIZE,
405 )
406
407 with server_manager:
408 yield server_manager
409
410
411 @pytest.fixture
412 def servers(server_manager):
413 return server_manager.servers
414
415
416 @pytest.fixture(scope="module", params=[1, 4])
417 def api_only_servers(request, default_server_args):
418 """Fixture for API-only server + headless engines configuration."""
419 api_server_count = request.param
420 with APIOnlyServerManager(
421 MODEL_NAME, DP_SIZE, api_server_count, default_server_args, TP_SIZE
422 ) as server_list:
423 yield server_list
424
425
426 @pytest_asyncio.fixture
427 async def client(servers: list[tuple[RemoteOpenAIServer, list[str]]]):
428 # For internal LB, we only connect to the head node (rank 0)
429 # which provides the single API endpoint
430 head_server = servers[0][0]
431 async with head_server.get_async_client() as client:
432 yield client
433
434
435 @pytest_asyncio.fixture
436 async def api_only_client(api_only_servers: list[tuple[RemoteOpenAIServer, list[str]]]):
437 """Client fixture for API-only server configuration."""
438 # Connect to the API-only server (first server in the list)
439 api_server = api_only_servers[0][0]
440 async with api_server.get_async_client() as client:
441 yield client
442
443
444 def _get_parallel_config(server: RemoteOpenAIServer):
445 response = requests.get(server.url_for("server_info?config_format=json"))
446 response.raise_for_status()
447
448 vllm_config = response.json()["vllm_config"]
449 return vllm_config["parallel_config"]
450
451
452 def test_multinode_dp_server_info(server_manager):
453 head_server = server_manager.servers[0][0]
454 api_server_count = server_manager.api_server_count
455
456 # Each request will hit one of the API servers
457 # `n_reqs` is set so that there is a good chance each server
458 # receives at least one request
459 n_reqs = 2 * api_server_count * api_server_count
460 parallel_configs = [_get_parallel_config(head_server) for _ in range(n_reqs)]
461 api_process_counts = [c["_api_process_count"] for c in parallel_configs]
462 api_process_ranks = [c["_api_process_rank"] for c in parallel_configs]
463
464 assert all(c == api_server_count for c in api_process_counts), api_process_counts
465 assert all(0 <= r < api_server_count for r in api_process_ranks), api_process_ranks
466
467
468 @pytest.mark.asyncio
469 @pytest.mark.parametrize(
470 "model_name",
471 [MODEL_NAME],
472 )
473 async def test_multinode_dp_completion(
474 client: openai.AsyncOpenAI,
475 servers: list[tuple[RemoteOpenAIServer, list[str]]],
476 model_name: str,
477 ) -> None:
478 # Test single request
479 result = await _make_completion_request(client, model_name)
480 assert result is not None
481 print("Multi-node internal LB handled single completion request successfully")
482
483 await asyncio.sleep(0.5)
484
485 # Send multiple bursts - internal LB should distribute across DP ranks
486 await _run_request_bursts(client, model_name)
487
488 _, server_args = servers[0]
489 api_server_count = (
490 server_args.count("--api-server-count")
491 and server_args[server_args.index("--api-server-count") + 1]
492 or 1
493 )
494 print(
495 f"Successfully completed multi-node internal LB test with "
496 f"{len(servers)} DP ranks (API server count: {api_server_count})"
497 )
498
499 # Check request balancing via Prometheus metrics
500 head_server = servers[0][0]
501 check_request_balancing(head_server, DP_SIZE)
502
503
504 @pytest.mark.asyncio
505 @pytest.mark.parametrize(
506 "model_name",
507 [MODEL_NAME],
508 )
509 async def test_multinode_dp_completion_streaming(
510 client: openai.AsyncOpenAI,
511 servers: list[tuple[RemoteOpenAIServer, list[str]]],
512 model_name: str,
513 ) -> None:
514 prompt = "What is an LLM?"
515
516 async def make_streaming_request():
517 # Perform a non-streaming request to get the expected full output
518 single_completion = await client.completions.create(
519 model=model_name,
520 prompt=prompt,
521 max_tokens=5,
522 temperature=0.0,
523 )
524 single_output = single_completion.choices[0].text
525
526 # Perform the streaming request
527 stream = await client.completions.create(
528 model=model_name, prompt=prompt, max_tokens=5, temperature=0.0, stream=True
529 )
530 chunks: list[str] = []
531 finish_reason_count = 0
532 last_chunk = None
533 async for chunk in stream:
534 chunks.append(chunk.choices[0].text)
535 if chunk.choices[0].finish_reason is not None:
536 finish_reason_count += 1
537 last_chunk = chunk # Keep track of the last chunk
538
539 # finish reason should only return in the last block for OpenAI API
540 assert finish_reason_count == 1, "Finish reason should appear exactly once."
541 assert last_chunk is not None, "Stream should have yielded at least one chunk."
542 assert last_chunk.choices[0].finish_reason == "length", (
543 "Finish reason should be 'length'."
544 )
545 # Check that the combined text matches the non-streamed version.
546 assert "".join(chunks) == single_output, (
547 "Streamed output should match non-streamed output."
548 )
549 return True # Indicate success for this request
550
551 # Test single streaming request
552 result = await make_streaming_request()
553 assert result is not None
554 print("Multi-node internal LB handled single streaming request successfully")
555
556 await asyncio.sleep(0.5)
557
558 # Send multiple streaming requests - internal LB should distribute across
559 # DP ranks
560 num_requests = 200
561 all_tasks = []
562 for _ in range(num_requests):
563 all_tasks.append(asyncio.create_task(make_streaming_request()))
564 await asyncio.sleep(0.01)
565
566 results = await asyncio.gather(*all_tasks)
567 assert len(results) == num_requests
568 assert all(results), "Not all streaming requests completed successfully."
569
570 await asyncio.sleep(0.5)
571
572 # Second burst of streaming requests
573 all_tasks = []
574 for _ in range(num_requests):
575 all_tasks.append(asyncio.create_task(make_streaming_request()))
576 await asyncio.sleep(0.01)
577
578 results = await asyncio.gather(*all_tasks)
579 assert len(results) == num_requests
580 assert all(results), "Not all streaming requests completed successfully."
581
582 _, server_args = servers[0]
583 api_server_count = (
584 server_args.count("--api-server-count")
585 and server_args[server_args.index("--api-server-count") + 1]
586 or 1
587 )
588 print(
589 f"Successfully completed multi-node internal LB streaming test with "
590 f"{len(servers)} DP ranks (API server count: {api_server_count})"
591 )
592
593 # Check request balancing via Prometheus metrics
594 head_server = servers[0][0]
595 check_request_balancing(head_server, DP_SIZE)
596
597
598 @pytest.mark.asyncio
599 @pytest.mark.parametrize(
600 "model_name",
601 [MODEL_NAME],
602 )
603 async def test_api_only_multinode_dp_completion(
604 api_only_client: openai.AsyncOpenAI,
605 api_only_servers: list[tuple[RemoteOpenAIServer, list[str]]],
606 model_name: str,
607 ) -> None:
608 """Test API-only server with all engines on separate headless server."""
609 # Test single request
610 result = await _make_completion_request(api_only_client, model_name)
611 assert result is not None
612 print("API-only server handled single completion request successfully")
613
614 await asyncio.sleep(0.5)
615
616 # Send multiple bursts - should be distributed across engines on
617 # headless server
618 await _run_request_bursts(api_only_client, model_name)
619
620 api_server, api_server_args = api_only_servers[0]
621 api_server_count = (
622 api_server_args.count("--api-server-count")
623 and api_server_args[api_server_args.index("--api-server-count") + 1]
624 or 1
625 )
626 print(
627 f"Successfully completed API-only multi-node test with {DP_SIZE} "
628 f"engines on headless server (API server count: {api_server_count})"
629 )
630
631 # Check request balancing via Prometheus metrics
632 check_request_balancing(api_server, DP_SIZE)
633
634
635 @pytest.mark.asyncio
636 @pytest.mark.parametrize(
637 "model_name",
638 [MODEL_NAME],
639 )
640 async def test_api_only_multinode_dp_completion_streaming(
641 api_only_client: openai.AsyncOpenAI,
642 api_only_servers: list[tuple[RemoteOpenAIServer, list[str]]],
643 model_name: str,
644 ) -> None:
645 """Test API-only server streaming with all engines on separate
646 headless server."""
647 prompt = "What is an LLM?"
648
649 async def make_streaming_request():
650 # Perform a non-streaming request to get the expected full output
651 single_completion = await api_only_client.completions.create(
652 model=model_name,
653 prompt=prompt,
654 max_tokens=5,
655 temperature=0.0,
656 )
657 single_output = single_completion.choices[0].text
658
659 # Perform the streaming request
660 stream = await api_only_client.completions.create(
661 model=model_name, prompt=prompt, max_tokens=5, temperature=0.0, stream=True
662 )
663 chunks: list[str] = []
664 finish_reason_count = 0
665 last_chunk = None
666 async for chunk in stream:
667 chunks.append(chunk.choices[0].text)
668 if chunk.choices[0].finish_reason is not None:
669 finish_reason_count += 1
670 last_chunk = chunk # Keep track of the last chunk
671
672 # finish reason should only return in the last block for OpenAI API
673 assert finish_reason_count == 1, "Finish reason should appear exactly once."
674 assert last_chunk is not None, "Stream should have yielded at least one chunk."
675 assert last_chunk.choices[0].finish_reason == "length", (
676 "Finish reason should be 'length'."
677 )
678 # Check that the combined text matches the non-streamed version.
679 assert "".join(chunks) == single_output, (
680 "Streamed output should match non-streamed output."
681 )
682 return True # Indicate success for this request
683
684 # Test single streaming request
685 result = await make_streaming_request()
686 assert result is not None
687 print("API-only server handled single streaming request successfully")
688
689 await asyncio.sleep(0.5)
690
691 # Send multiple streaming requests - should be distributed across engines
692 num_requests = 200
693 all_tasks = []
694 for _ in range(num_requests):
695 all_tasks.append(asyncio.create_task(make_streaming_request()))
696 await asyncio.sleep(0.01)
697
698 results = await asyncio.gather(*all_tasks)
699 assert len(results) == num_requests
700 assert all(results), "Not all streaming requests completed successfully."
701
702 await asyncio.sleep(0.5)
703
704 # Second burst of streaming requests
705 all_tasks = []
706 for _ in range(num_requests):
707 all_tasks.append(asyncio.create_task(make_streaming_request()))
708 await asyncio.sleep(0.01)
709
710 results = await asyncio.gather(*all_tasks)
711 assert len(results) == num_requests
712 assert all(results), "Not all streaming requests completed successfully."
713
714 _, api_server_args = api_only_servers[0]
715 api_server_count = (
716 api_server_args.count("--api-server-count")
717 and api_server_args[api_server_args.index("--api-server-count") + 1]
718 or 1
719 )
720 print(
721 f"Successfully completed API-only streaming test with {DP_SIZE} "
722 f"engines on headless server (API server count: {api_server_count})"
723 )
724
725 # Check request balancing via Prometheus metrics
726 api_server = api_only_servers[0][0]
727 check_request_balancing(api_server, DP_SIZE)