[V1] V1 Enablement Oracle

[robertgshaw2-redhat]

SUMMARY:

• adds oracle for V1 feature enablement
• removes usage of envs.VLLM_USE_V1 from code base (now only used in tests + in oracle)
• enables V1 by default

BEHAVIOR

# * If VLLM_USE_V1 is unset, we enable V1 for "supported features"
#   and fall back to V0 for experimental or unsupported features.
# * If VLLM_USE_V1=1, we enable V1 for supported + experimental
#   features and raise error for unsupported features.
# * If VLLM_USE_V1=0, we disable V1.

UX:

• if the user specifies .from_vllm_config, we can autodetect the engine and it works nicely

from vllm.engine.async_llm_engine import AsyncLLMEngine
args = AsyncEngineArgs(...)

# sets VLLM_USE_V1 to 0 or 1 if unset by the user
config = args.create_engine_config() 

# autoselects V1 engine if VLLM_USE_V1 is 1
async_llm_engine = AsyncLLMEngine.from_vllm_config(config, ...)

• if the user uses AsyncLLMEngine.__init__() this will not work

from vllm.engine.async_llm_engine import AsyncLLMEngine
args = AsyncEngineArgs(...)

# sets VLLM_USE_V1 to 0 or 1 if unset by the user
config = args.create_engine_config()

# this uses the V0 constructor, raises ValueError
async_llm_engine = AsyncLLMEngine(config, ...)

# >> raise ValueError(
# >>                "Using V1 LLMEngine, but envs.VLLM_USE_V1=True. "
# >>                "This should not happen. As a workaround, try using "
# >>                "LLMEngine.from_vllm_config(...) or explicitly set "
# >>                "VLLM_USE_V1=0 or 1 and report this issue on Github.")

TODOs:

• get CI green

[github-actions]

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[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @robertgshaw2-redhat.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

stale

[simon-mo]

from rob

openai tool use --> looks like a numerics issue. We are comparing against a golden string
I will post a PR in the AM to update the golden string
extended models --> this fails on main

[DarkLight1337]

Nice work!