debug radixcache stack_overflow

[luzengxiangcn]

Motivation

A bug happens in 3 hours whe running pressure test on a A800*4 with Qwen2-72B.
Error Trace ：

• Location:

/sglang/python/sglang/srt/mem_cache/radix_cache.py
-- class RadixCache
     -- def _collect_leaves
        -- def dfs_

• Error:
  Too many times recursion causes stack overflow.

Python Stack Overflow

Modifications

For radix cache, replace recursion with stask for dfs search.

Checklist

• Format your code according to the Contributor Guide.
• Add unit tests as outlined in the Contributor Guide.
• Update documentation as needed, including docstrings or example tutorials.

[luzengxiangcn]

Motivation

A bug happens in 3 hours whe running pressure test on a A800*4 with Qwen2-72B. Error Trace ：

• Location:

/sglang/python/sglang/srt/mem_cache/radix_cache.py
-- class RadixCache
     -- def _collect_leaves
        -- def dfs_

• Error:
  Too many times recursion causes stack overflow.

Python Stack Overflow

Modifications

For radix cache, replace recursion with stask for dfs search.

Checklist

• Format your code according to the Contributor Guide.
• Add unit tests as outlined in the Contributor Guide.
• Update documentation as needed, including docstrings or example tutorials.