Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

[Bug]: Empty prompt kills vllm server (AsyncEngineDeadError: Background loop is stopped.) #7283

Closed
shimizust opened this issue Aug 7, 2024 · 8 comments
Closed

[Bug]: Empty prompt kills vllm server (AsyncEngineDeadError: Background loop is stopped.) #7283

shimizust opened this issue Aug 7, 2024 · 8 comments
Labels
bug Something isn't working

Comments

@shimizust
Copy link

shimizust commented Aug 7, 2024 •
edited
Loading

Your current environment

python3 collect_env.py 
Collecting environment information...
PyTorch version: 2.3.1+cu121
Is debug build: False
CUDA used to build PyTorch: 12.1
ROCM used to build PyTorch: N/A

OS: Ubuntu 20.04.6 LTS (x86_64)
GCC version: (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0
Clang version: Could not collect
CMake version: version 3.30.1
Libc version: glibc-2.31

Python version: 3.10.14 (main, Apr  6 2024, 18:45:05) [GCC 9.4.0] (64-bit runtime)
Python platform: Linux-5.15.138.1-4.cm2-x86_64-with-glibc2.31
Is CUDA available: True
CUDA runtime version: Could not collect
CUDA_MODULE_LOADING set to: LAZY
GPU models and configuration: GPU 0: NVIDIA A100-SXM4-80GB
Nvidia driver version: 525.85.12
cuDNN version: Could not collect
HIP runtime version: N/A
MIOpen runtime version: N/A
Is XNNPACK available: True

CPU:
Architecture:                       x86_64
CPU op-mode(s):                     32-bit, 64-bit
Byte Order:                         Little Endian
Address sizes:                      48 bits physical, 48 bits virtual
CPU(s):                             256
On-line CPU(s) list:                0-255
Thread(s) per core:                 2
Core(s) per socket:                 64
Socket(s):                          2
NUMA node(s):                       8
Vendor ID:                          AuthenticAMD
CPU family:                         25
Model:                              1
Model name:                         AMD EPYC 7763 64-Core Processor
Stepping:                           1
Frequency boost:                    enabled
CPU MHz:                            3096.040
CPU max MHz:                        3529.0520
CPU min MHz:                        1500.0000
BogoMIPS:                           4900.05
Virtualization:                     AMD-V
L1d cache:                          4 MiB
L1i cache:                          4 MiB
L2 cache:                           64 MiB
L3 cache:                           512 MiB
NUMA node0 CPU(s):                  0-15,128-143
NUMA node1 CPU(s):                  16-31,144-159
NUMA node2 CPU(s):                  32-47,160-175
NUMA node3 CPU(s):                  48-63,176-191
NUMA node4 CPU(s):                  64-79,192-207
NUMA node5 CPU(s):                  80-95,208-223
NUMA node6 CPU(s):                  96-111,224-239
NUMA node7 CPU(s):                  112-127,240-255
Vulnerability Gather data sampling: Not affected
Vulnerability Itlb multihit:        Not affected
Vulnerability L1tf:                 Not affected
Vulnerability Mds:                  Not affected
Vulnerability Meltdown:             Not affected
Vulnerability Mmio stale data:      Not affected
Vulnerability Retbleed:             Not affected
Vulnerability Spec rstack overflow: Mitigation; safe RET, no microcode
Vulnerability Spec store bypass:    Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:           Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:           Mitigation; Retpolines, IBPB conditional, IBRS_FW, STIBP always-on, RSB filling, PBRSB-eIBRS Not affected
Vulnerability Srbds:                Not affected
Vulnerability Tsx async abort:      Not affected
Flags:                              fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf rapl pni pclmulqdq monitor ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb cat_l3 cdp_l3 invpcid_single hw_pstate ssbd mba ibrs ibpb stibp vmmcall fsgsbase bmi1 avx2 smep bmi2 invpcid cqm rdt_a rdseed adx smap clflushopt clwb sha_ni xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local clzero irperf xsaveerptr rdpru wbnoinvd amd_ppin arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold v_vmsave_vmload vgif v_spec_ctrl umip pku ospke vaes vpclmulqdq rdpid overflow_recov succor smca

Versions of relevant libraries:
[pip3] flashinfer==0.0.9+cu121torch2.3
[pip3] numpy==1.26.4
[pip3] nvidia-nccl-cu12==2.20.5
[pip3] pyzmq==26.0.3
[pip3] torch==2.3.1
[pip3] torchvision==0.18.1
[pip3] transformers==4.43.2
[pip3] triton==2.3.1
[conda] Could not collect
ROCM Version: Could not collect
Neuron SDK Version: N/A
vLLM Version: 0.5.3.post1
vLLM Build Flags:
CUDA Archs: Not Set; ROCm: Disabled; Neuron: Disabled
GPU Topology:
GPU0    CPU Affinity    NUMA Affinity
GPU0     X      48-63,176-191   3

Legend:

  X    = Self
  SYS  = Connection traversing PCIe as well as the SMP interconnect between NUMA nodes (e.g., QPI/UPI)
  NODE = Connection traversing PCIe as well as the interconnect between PCIe Host Bridges within a NUMA node
  PHB  = Connection traversing PCIe as well as a PCIe Host Bridge (typically the CPU)
  PXB  = Connection traversing multiple PCIe bridges (without traversing the PCIe Host Bridge)
  PIX  = Connection traversing at most a single PCIe bridge
  NV#  = Connection traversing a bonded set of # NVLinks

🐛 Describe the bug

Spin up the vllm server in a pod using the vllm base image (vllm/vllm-openai:v0.5.3.post1)

python3 -m vllm.entrypoints.openai.api_server --model $MODEL_PATH --port 8000 --trust-remote-code

where $MODEL_PATH points to some model. I've tried gpt2-medium and Meta-Llama-3-8B.

Generation works fine, but if you pass in an empty prompt, it immediately kills the server and is unrecoverable:

curl -X 'POST' \
  'http://localhost:8080/v1/completions' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "/models/gpt2-medium",
  "prompt": "",
  "max_tokens": 50,
  "temperature": 0.9,
  "top_p": 1
}'

INFO 08-07 20:13:55 logger.py:36] Received request cmpl-662a1639b80b47539cc099bdf6347cc0-0: prompt: '', params: SamplingParams(n=1, best_of=1, presence_penalty=0.0, frequency_penalty=0.0, repetition_penalty=1.0, temperature=0.9, top_p=0.9, top_k=20, min_p=0.0, seed=None, use_beam_search=False, length_penalty=1.0, early_stopping=False, stop=[], stop_token_ids=[], include_stop_str_in_output=False, ignore_eos=False, max_tokens=100, min_tokens=0, logprobs=None, prompt_logprobs=None, skip_special_tokens=True, spaces_between_special_tokens=True, truncate_prompt_tokens=None), prompt_token_ids: [], lora_request: None, prompt_adapter_request: None.
INFO 08-07 20:13:55 async_llm_engine.py:173] Added request cmpl-662a1639b80b47539cc099bdf6347cc0-0.
ERROR 08-07 20:13:55 async_llm_engine.py:56] Engine background task failed
ERROR 08-07 20:13:55 async_llm_engine.py:56] Traceback (most recent call last):
ERROR 08-07 20:13:55 async_llm_engine.py:56]   File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 46, in _log_task_completion
ERROR 08-07 20:13:55 async_llm_engine.py:56]     return_value = task.result()
ERROR 08-07 20:13:55 async_llm_engine.py:56]   File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 637, in run_engine_loop
ERROR 08-07 20:13:55 async_llm_engine.py:56]     result = task.result()
ERROR 08-07 20:13:55 async_llm_engine.py:56]   File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 580, in engine_step
ERROR 08-07 20:13:55 async_llm_engine.py:56]     request_outputs = await self.engine.step_async(virtual_engine)
ERROR 08-07 20:13:55 async_llm_engine.py:56]   File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 238, in step_async
ERROR 08-07 20:13:55 async_llm_engine.py:56]     virtual_engine].schedule()
ERROR 08-07 20:13:55 async_llm_engine.py:56]   File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 978, in schedule
ERROR 08-07 20:13:55 async_llm_engine.py:56]     scheduler_outputs = self._schedule()
ERROR 08-07 20:13:55 async_llm_engine.py:56]   File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 953, in _schedule
ERROR 08-07 20:13:55 async_llm_engine.py:56]     return self._schedule_default()
ERROR 08-07 20:13:55 async_llm_engine.py:56]   File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 795, in _schedule_default
ERROR 08-07 20:13:55 async_llm_engine.py:56]     remaining_waiting, prefills = self._schedule_prefills(
ERROR 08-07 20:13:55 async_llm_engine.py:56]   File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 690, in _schedule_prefills
ERROR 08-07 20:13:55 async_llm_engine.py:56]     num_new_tokens = self._get_num_new_tokens(seq_group,
ERROR 08-07 20:13:55 async_llm_engine.py:56]   File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 1232, in _get_num_new_tokens
ERROR 08-07 20:13:55 async_llm_engine.py:56]     assert num_new_tokens > 0
ERROR 08-07 20:13:55 async_llm_engine.py:56] AssertionError
Exception in callback functools.partial(<function _log_task_completion at 0x7b3f96884790>, error_callback=<bound method AsyncLLMEngine._error_callback of <vllm.engine.async_llm_engine.AsyncLLMEngine object at 0x7b3f7e2f7be0>>)
INFO 08-07 20:13:55 async_llm_engine.py:180] Aborted request cmpl-662a1639b80b47539cc099bdf6347cc0-0.
handle: <Handle functools.partial(<function _log_task_completion at 0x7b3f96884790>, error_callback=<bound method AsyncLLMEngine._error_callback of <vllm.engine.async_llm_engine.AsyncLLMEngine object at 0x7b3f7e2f7be0>>)>
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 46, in _log_task_completion
    return_value = task.result()
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 637, in run_engine_loop
    result = task.result()
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 580, in engine_step
    request_outputs = await self.engine.step_async(virtual_engine)
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 238, in step_async
    virtual_engine].schedule()
  File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 978, in schedule
    scheduler_outputs = self._schedule()
  File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 953, in _schedule
    return self._schedule_default()
  File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 795, in _schedule_default
    remaining_waiting, prefills = self._schedule_prefills(
  File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 690, in _schedule_prefills
    num_new_tokens = self._get_num_new_tokens(seq_group,
INFO:     100.99.173.128:58497 - "POST /v1/completions HTTP/1.1" 500 Internal Server Error
  File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 1232, in _get_num_new_tokens
    assert num_new_tokens > 0
AssertionError

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "uvloop/cbhandles.pyx", line 63, in uvloop.loop.Handle._run
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 58, in _log_task_completion
    raise AsyncEngineDeadError(
vllm.engine.async_llm_engine.AsyncEngineDeadError: Task finished unexpectedly. This should never happen! Please open an issue on Github. See stack trace above for theactual cause.
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/dist-packages/uvicorn/protocols/http/httptools_impl.py", line 399, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
  File "/usr/local/lib/python3.10/dist-packages/uvicorn/middleware/proxy_headers.py", line 70, in __call__
    return await self.app(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/fastapi/applications.py", line 1054, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/applications.py", line 123, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/cors.py", line 85, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/exceptions.py", line 65, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.10/dist-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 756, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 776, in app
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 297, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 77, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.10/dist-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 72, in app
    response = await func(request)
  File "/usr/local/lib/python3.10/dist-packages/fastapi/routing.py", line 278, in app
    raw_response = await run_endpoint_function(
  File "/usr/local/lib/python3.10/dist-packages/fastapi/routing.py", line 191, in run_endpoint_function
    return await dependant.call(**values)
  File "/usr/local/lib/python3.10/dist-packages/vllm/entrypoints/openai/api_server.py", line 144, in create_completion
    generator = await openai_serving_completion.create_completion(
  File "/usr/local/lib/python3.10/dist-packages/vllm/entrypoints/openai/serving_completion.py", line 175, in create_completion
    async for i, res in result_generator:
  File "/usr/local/lib/python3.10/dist-packages/vllm/utils.py", line 329, in consumer
    raise e
  File "/usr/local/lib/python3.10/dist-packages/vllm/utils.py", line 320, in consumer
    raise item
  File "/usr/local/lib/python3.10/dist-packages/vllm/utils.py", line 304, in producer
    async for item in iterator:
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 772, in generate
    async for output in self._process_request(
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 888, in _process_request
    raise e
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 884, in _process_request
    async for request_output in stream:
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 93, in __anext__
    raise result
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 46, in _log_task_completion
    return_value = task.result()
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 637, in run_engine_loop
    result = task.result()
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 580, in engine_step
    request_outputs = await self.engine.step_async(virtual_engine)
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 238, in step_async
    virtual_engine].schedule()
  File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 978, in schedule
    scheduler_outputs = self._schedule()
  File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 953, in _schedule
    return self._schedule_default()
  File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 795, in _schedule_default
    remaining_waiting, prefills = self._schedule_prefills(
  File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 690, in _schedule_prefills
    num_new_tokens = self._get_num_new_tokens(seq_group,
  File "/usr/local/lib/python3.10/dist-packages/vllm/core/scheduler.py", line 1232, in _get_num_new_tokens
    assert num_new_tokens > 0
AssertionError
INFO 08-07 20:13:57 metrics.py:396] Avg prompt throughput: 0.0 tokens/s, Avg generation throughput: 0.0 tokens/s, Running: 0 reqs, Swapped: 0 reqs, Pending: 1 reqs, GPU KV cache usage: 0.0%, CPU KV cache usage: 0.0%.
INFO:     100.96.103.1:43785 - "GET /health HTTP/1.1" 500 Internal Server Error
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/dist-packages/uvicorn/protocols/http/httptools_impl.py", line 399, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
  File "/usr/local/lib/python3.10/dist-packages/uvicorn/middleware/proxy_headers.py", line 70, in __call__
    return await self.app(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/fastapi/applications.py", line 1054, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/applications.py", line 123, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/cors.py", line 85, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/middleware/exceptions.py", line 65, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.10/dist-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 756, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 776, in app
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 297, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 77, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/usr/local/lib/python3.10/dist-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.10/dist-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.10/dist-packages/starlette/routing.py", line 72, in app
    response = await func(request)
  File "/usr/local/lib/python3.10/dist-packages/fastapi/routing.py", line 278, in app
    raw_response = await run_endpoint_function(
  File "/usr/local/lib/python3.10/dist-packages/fastapi/routing.py", line 191, in run_endpoint_function
    return await dependant.call(**values)
  File "/usr/local/lib/python3.10/dist-packages/vllm/entrypoints/openai/api_server.py", line 88, in health
    await openai_serving_chat.engine.check_health()
  File "/usr/local/lib/python3.10/dist-packages/vllm/engine/async_llm_engine.py", line 950, in check_health
    raise AsyncEngineDeadError("Background loop is stopped.")
vllm.engine.async_llm_engine.AsyncEngineDeadError: Background loop is stopped.

Expected Behavior

If an empty prompt is not allowed, I would expect a 400 invalid input response vs. a 500 that stops the server.
@shimizust shimizust added the bug Something isn't working label Aug 7, 2024
@shimizust shimizust changed the title [Bug]: Empty prompt kills vllm server [Bug]: Empty prompt kills vllm server (AsyncEngineDeadError: Background loop is stopped.) Aug 7, 2024
@mgoin
Copy link
Member

mgoin commented Aug 7, 2024

This also happens for the offline LLM entrypoint:

>>> from vllm import LLM
>>> model = LLM("gpt2")
>>> model.generate("")
Processed prompts:   0%|                                                                                                                          | 0/1 [00:00<?, ?it/s, est. speed input: 0.00 toks/s, output: 0.00 toks/s][rank0]: Traceback (most recent call last):
[rank0]:   File "<stdin>", line 1, in <module>
[rank0]:   File "/home/mgoin/code/vllm/vllm/utils.py", line 996, in inner
[rank0]:     return fn(*args, **kwargs)
[rank0]:   File "/home/mgoin/code/vllm/vllm/entrypoints/llm.py", line 339, in generate
[rank0]:     outputs = self._run_engine(use_tqdm=use_tqdm)
[rank0]:   File "/home/mgoin/code/vllm/vllm/entrypoints/llm.py", line 620, in _run_engine
[rank0]:     step_outputs = self.llm_engine.step()
[rank0]:   File "/home/mgoin/code/vllm/vllm/engine/llm_engine.py", line 1287, in step
[rank0]:     0].schedule()
[rank0]:   File "/home/mgoin/code/vllm/vllm/core/scheduler.py", line 963, in schedule
[rank0]:     scheduler_outputs = self._schedule()
[rank0]:   File "/home/mgoin/code/vllm/vllm/core/scheduler.py", line 938, in _schedule
[rank0]:     return self._schedule_default()
[rank0]:   File "/home/mgoin/code/vllm/vllm/core/scheduler.py", line 798, in _schedule_default
[rank0]:     prefills = self._schedule_prefills(budget,
[rank0]:   File "/home/mgoin/code/vllm/vllm/core/scheduler.py", line 696, in _schedule_prefills
[rank0]:     num_new_tokens = self._get_num_new_tokens(seq_group,
[rank0]:   File "/home/mgoin/code/vllm/vllm/core/scheduler.py", line 1234, in _get_num_new_tokens
[rank0]:     assert num_new_tokens > 0
[rank0]: AssertionError

@youkaichao
Copy link
Member

Just curious, I think LLM always starts with a start_of_sentence token? What does empty prompt mean then?

@mgoin
Copy link
Member

mgoin commented Aug 7, 2024 •
edited
Loading

@youkaichao this depends on the tokenizer. I just tested llama 3.1 8b instruct and it doesn't have this issue because it has a BOS token:

>>> from vllm import LLM
>>> model = LLM("meta-llama/Meta-Llama-3.1-8B-Instruct")
>>> model.generate("")
Processed prompts: 100%|████████████████████████████████████████████████████████████████████████████████████████████████████████████████| 1/1 [00:00<00:00,  7.37it/s, est. speed input: 7.38 toks/s, output: 118.09 toks/s]
[RequestOutput(request_id=0, prompt='', prompt_token_ids=[128000], encoder_prompt=None, encoder_prompt_token_ids=None, prompt_logprobs=None, outputs=[CompletionOutput(index=0, text='Cloud bathroom mirror is designed to bring a fresh perspective to bathroom essentials. Its fog', token_ids=(16440, 15197, 18327, 374, 6319, 311, 4546, 264, 7878, 13356, 311, 15197, 59886, 13, 11699, 31349), cumulative_logprob=None, logprobs=None, finish_reason=length, stop_reason=None)], finished=True, metrics=RequestMetrics(arrival_time=1723074368.5084124, last_token_time=1723074368.5084124, first_scheduled_time=1723074368.5245223, first_token_time=1723074368.5398314, time_in_queue=0.016109943389892578, finished_time=1723074368.6597202), lora_request=None)]

You can see the prompt is empty but the prompt token ids is not prompt='', prompt_token_ids=[128000]

Either way, I think we should return an empty response or otherwise follow what openai does for empty prompt. Crashing LLM or the server is not good behavior.

@youkaichao
Copy link
Member

Crashing LLM or the server is not good behavior

agree. we should never let user request crash the engine.

@shimizust
Copy link
Author

Good catch that this depends on the tokenizer. The models I tested do not have the bos token defined in the tokenizer_config.json.

@pseudotensor
Copy link

Same as this: #7632

@tjohnson31415
Copy link
Contributor

#7632 was closed after the fix in #7746. This issue can be closed too.

@mgoin
Copy link
Member

mgoin commented Oct 17, 2024

Thanks for ping, closing as resolved

@mgoin mgoin closed this as completed Oct 17, 2024
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
bug Something isn't working
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
5 participants
@pseudotensor @mgoin @tjohnson31415 @youkaichao @shimizust