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fix: add None check before stream synchronization#2810

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deng451e merged 4 commits intoLMCache:devfrom
hlin99:ww12_PR_fix_stream
Mar 19, 2026
Merged

fix: add None check before stream synchronization#2810
deng451e merged 4 commits intoLMCache:devfrom
hlin99:ww12_PR_fix_stream

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@hlin99 hlin99 commented Mar 18, 2026

Prevent AttributeError by ensuring the stream object is not None before calling stream.synchronize().

otherwise, crash will happen on non-cuda devices.

Prevent AttributeError by ensuring the stream object is not None before calling stream.synchronize().

Signed-off-by: Tony Lin <tony.lin@intel.com>
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Summary of Changes

Hello, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical bug that could lead to an AttributeError when running on environments without CUDA support. By introducing a conditional check, it ensures that stream synchronization is only attempted when a valid stream object is present, thereby enhancing the robustness and cross-device compatibility of the memory allocation and copying logic.

Highlights

  • Bug Fix: Implemented a None check for the stream object before attempting to call stream.synchronize() to prevent AttributeError.
  • Device Compatibility: Resolved a potential crash scenario that could occur on non-CUDA devices where the stream object might be None.
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Code Review

This pull request correctly addresses a potential AttributeError by adding a None check before calling stream.synchronize() in the allocate_and_copy_objects function. This change prevents a crash when running on non-CUDA devices where the CUDA stream object would be None. The fix is correct and well-targeted. I've added one suggestion to improve type hinting for maintainability.

Comment on lines +114 to +115
if stream is not None:
stream.synchronize()
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medium

This check correctly handles cases where stream can be None. To improve type safety and make this explicit for future developers, consider updating the function's type hint for the stream parameter from torch.cuda.Stream to Optional[torch.cuda.Stream].

For example:

def allocate_and_copy_objects(
    ...,
    stream: Optional[torch.cuda.Stream],
) -> ...:

@deng451e deng451e self-requested a review March 18, 2026 04:39
@deng451e deng451e enabled auto-merge (squash) March 18, 2026 04:41
@github-actions github-actions Bot added the full Run comprehensive tests on this PR label Mar 18, 2026
@deng451e deng451e merged commit 3f1c00f into LMCache:dev Mar 19, 2026
24 of 28 checks passed
hyunyul-XCENA pushed a commit to xcena-dev/LMCache that referenced this pull request Mar 20, 2026
Prevent AttributeError by ensuring the stream object is not None before calling stream.synchronize().

Signed-off-by: Tony Lin <tony.lin@intel.com>
realAaronWu pushed a commit to realAaronWu/LMCache that referenced this pull request Mar 20, 2026
Prevent AttributeError by ensuring the stream object is not None before calling stream.synchronize().

Signed-off-by: Tony Lin <tony.lin@intel.com>
Signed-off-by: Aaron Wu <aaron.wu@dell.com>
deng451e pushed a commit to deng451e/LMCache that referenced this pull request Mar 21, 2026
Prevent AttributeError by ensuring the stream object is not None before calling stream.synchronize().

Signed-off-by: Tony Lin <tony.lin@intel.com>
deng451e pushed a commit to deng451e/LMCache that referenced this pull request Mar 25, 2026
Prevent AttributeError by ensuring the stream object is not None before calling stream.synchronize().

Signed-off-by: Tony Lin <tony.lin@intel.com>
deng451e pushed a commit to deng451e/LMCache that referenced this pull request Mar 27, 2026
Prevent AttributeError by ensuring the stream object is not None before calling stream.synchronize().

Signed-off-by: Tony Lin <tony.lin@intel.com>
jooho-XCENA pushed a commit to xcena-dev/LMCache that referenced this pull request Apr 2, 2026
Prevent AttributeError by ensuring the stream object is not None before calling stream.synchronize().

Signed-off-by: Tony Lin <tony.lin@intel.com>
jooho-XCENA pushed a commit to xcena-dev/LMCache that referenced this pull request Apr 2, 2026
Prevent AttributeError by ensuring the stream object is not None before calling stream.synchronize().

Signed-off-by: Tony Lin <tony.lin@intel.com>
@hlin99 hlin99 deleted the ww12_PR_fix_stream branch April 25, 2026 05:30
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3 participants