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[BUGFIX] fix value oom in radix tree#17400

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ispobock merged 1 commit intomainfrom
yizhang/fix_radix_cache_oom
Jan 21, 2026
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[BUGFIX] fix value oom in radix tree#17400
ispobock merged 1 commit intomainfrom
yizhang/fix_radix_cache_oom

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@yizhang2077 yizhang2077 commented Jan 20, 2026

Motivation

fix missing part in #17191

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  4. After green CI and required approvals, ask Merge Oncalls to merge.

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gemini-code-assist Bot commented Jan 20, 2026

Summary of Changes

Hello @yizhang2077, 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 potential Out-Of-Memory (OOM) issue within the radix tree cache by modifying how values are assigned to tree nodes. The core change involves introducing explicit cloning for host_value and value objects when they are stored in new or updated tree nodes. This ensures that each node holds an independent copy of its associated data, preventing unintended shared references that could lead to memory leaks or incorrect state, thereby completing a previous fix.

Highlights

  • Memory Management: Introduced cloning for host_value when creating new nodes in _insert_helper_host to prevent shared references and potential Out-Of-Memory (OOM) issues.
  • Radix Tree Value Handling: Ensured value is cloned when assigned to new TreeNode instances or updated in shared-prefix nodes within the insert method, guaranteeing independent copies.
  • Mamba Radix Cache Consistency: Applied similar cloning logic for value in mamba_radix_cache.py during node insertion to maintain consistent memory management across different radix tree implementations.

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@xiezhq-hermann xiezhq-hermann self-assigned this Jan 20, 2026
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gemini-code-assist Bot reviewed Jan 20, 2026
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Code Review

The pull request introduces .clone() calls when assigning value and host_value to TreeNode properties. This is a crucial change that addresses potential data corruption and out-of-memory (OOM) issues by ensuring that new nodes receive independent copies of tensor data rather than shared references. This prevents unintended modifications to node data when the original tensors or their slices are altered elsewhere in the program. The consistent application of .clone() across different insertion points in both hiradix_cache.py and mamba_radix_cache.py indicates a thorough fix for aliasing problems with mutable tensor values.

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ispobock commented Jan 20, 2026

/tag-and-rerun-ci

@ispobock ispobock merged commit 1b97fa7 into main Jan 21, 2026
196 of 221 checks passed
@ispobock ispobock deleted the yizhang/fix_radix_cache_oom branch January 21, 2026 09:13
gmixiaojin pushed a commit to gmixiaojin/sglang that referenced this pull request Jan 21, 2026
@yizhang2077 @gmixiaojin
[BUGFIX] fix value oom in radix tree (sgl-project#17400)
fd8a385
@ispobock ispobock mentioned this pull request Mar 8, 2026
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@ispobock ispobock ispobock approved these changes

@merrymercy merrymercy Awaiting requested review from merrymercy merrymercy is a code owner

@Ying1123 Ying1123 Awaiting requested review from Ying1123 Ying1123 is a code owner

@hnyls2002 hnyls2002 Awaiting requested review from hnyls2002 hnyls2002 is a code owner

@xiezhq-hermann xiezhq-hermann Awaiting requested review from xiezhq-hermann xiezhq-hermann is a code owner

@hanming-lu hanming-lu Awaiting requested review from hanming-lu hanming-lu is a code owner

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