[Bugfix] V1 Memory Profiling: V0 Sampler Integration without Rejection Sampler (#13594)

Signed-off-by: Jennifer Zhao <7443418+JenZhao@users.noreply.github.com>
Co-authored-by: Roger Wang <ywang@roblox.com>

vllm/v1/worker/gpu_model_runner.py

@@ -31,6 +31,7 @@ from vllm.v1.engine.mm_input_cache import MMInputCacheClient
 from vllm.v1.kv_cache_interface import (FullAttentionSpec, KVCacheConfig,
                                         KVCacheSpec)
 from vllm.v1.outputs import LogprobsTensors, ModelRunnerOutput
+from vllm.v1.sample.metadata import SamplingMetadata
 from vllm.v1.sample.rejection_sampler import INVALID_TOKEN_ID
 from vllm.v1.spec_decode.ngram_proposer import NgramProposer
 from vllm.v1.utils import bind_kv_cache
@@ -1305,11 +1306,34 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             if get_pp_group().is_last_rank:
                 hidden_states = hidden_states[logit_indices]
                 logits = self.model.compute_logits(hidden_states, None)
-                # TODO(woosuk): Consider the memory usage of the sampler.
+                dummy_tensors = lambda v: torch.full(
+                    (num_reqs, ), v, device=self.device)
+                dummy_metadata = SamplingMetadata(
+                    temperature=dummy_tensors(0.5),
+                    all_greedy=False,
+                    all_random=False,
+                    spec_token_ids=None,
+                    top_p=dummy_tensors(0.9),
+                    top_k=dummy_tensors(logits.size(1) - 1),
+                    min_p=None,
+                    generators={},
+                    max_num_logprobs=None,
+                    no_penalties=True,
+                    prompt_token_ids=torch.ones_like(logits, dtype=torch.int64),
+                    frequency_penalties=dummy_tensors(0.1),
+                    presence_penalties=dummy_tensors(0.1),
+                    repetition_penalties=dummy_tensors(0.1),
+                    output_token_ids=[[] for _ in range(num_reqs)],
+                    min_tokens={},
+                    logit_bias=[None for _ in range(num_reqs)])
+                sampler_output = self.model.sample(
+                    logits=logits, sampling_metadata=dummy_metadata)
             else:
                 logits = None
+                sampler_output = None
+                dummy_metadata = None
             torch.cuda.synchronize()
-            del hidden_states, logits
+            del hidden_states, logits, sampler_output, dummy_metadata
             self.encoder_cache.clear()
         gc.collect()