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A high-throughput and memory-efficient inference and serving engine for LLMs

Mirrored from https://github.com/tduncan-lum/Nvidia-Optimization-Stack---VLLM.git

Synced Nov 5, 12:15 UTC

[BugFix][MRV2] Fix cuda event reuse race (#39115)

Signed-off-by: Nick Hill <nickhill123@gmail.com>

Nick Hill committed Apr 6, 2026 at 17:21 UTC 62095e82c1ef7ed91be5223d36c6109958e9aec6
2 files changed +2 -7
vllm/v1/worker/gpu/async_utils.py
+2 -4
@@ -17,7 +17,6 @@ class AsyncOutput(AsyncModelRunnerOutput):
17 num_sampled_tokens: torch.Tensor,
18 main_stream: torch.cuda.Stream,
19 copy_stream: torch.cuda.Stream,
20 - copy_event: torch.cuda.Event,
20 ):
21 # NOTE(woosuk): We must retain references to the GPU tensors,
22 # as the copy operations are performed on a different CUDA stream than
@@ -25,7 +24,7 @@ class AsyncOutput(AsyncModelRunnerOutput):
24 self.model_runner_output = model_runner_output
25 self.sampler_output = sampler_output
26 self.num_sampled_tokens = num_sampled_tokens
28 - self.copy_event = copy_event
27 + self.copy_event = torch.cuda.Event()
28
29 with stream(copy_stream, main_stream):
30 copy_stream.wait_stream(main_stream)
@@ -78,12 +77,11 @@ class AsyncPoolingOutput(AsyncModelRunnerOutput):
77 is_valid: torch.Tensor | None,
78 main_stream: torch.cuda.Stream,
79 copy_stream: torch.cuda.Stream,
81 - copy_event: torch.cuda.Event,
80 ):
81 self.model_runner_output = model_runner_output
82 self.pooler_output = pooler_output
83 self.is_valid = is_valid
86 - self.copy_event = copy_event
84 + self.copy_event = torch.cuda.Event()
85
86 with stream(copy_stream, main_stream):
87 copy_stream.wait_stream(main_stream)
vllm/v1/worker/gpu/model_runner.py
-3
@@ -130,7 +130,6 @@ class GPUModelRunner(LoRAModelRunnerMixin):
130
131 self.use_async_scheduling = self.scheduler_config.async_scheduling
132 self.output_copy_stream = torch.cuda.Stream(self.device)
133 - self.output_copy_event = torch.cuda.Event()
133
134 # Pipeline parallelism.
135 self.use_pp = self.parallel_config.pipeline_parallel_size > 1
@@ -1180,7 +1179,6 @@ class GPUModelRunner(LoRAModelRunnerMixin):
1179 num_sampled_tokens=num_sampled,
1180 main_stream=self.main_stream,
1181 copy_stream=self.output_copy_stream,
1183 - copy_event=self.output_copy_event,
1182 )
1183
1184 mm_inputs: tuple[list[torch.Tensor], torch.Tensor] | None = None
@@ -1270,7 +1268,6 @@ class GPUModelRunner(LoRAModelRunnerMixin):
1268 is_valid=is_valid,
1269 main_stream=self.main_stream,
1270 copy_stream=self.output_copy_stream,
1273 - copy_event=self.output_copy_event,
1271 )
1272
1273 self.postprocess_pool(input_batch)