vchag opened a new pull request, #64040:
URL: https://github.com/apache/doris/pull/64040

   ### What problem does this PR solve?
   
   Issue Number: close 63193
   
   Related PR: [#2949](https://github.com/apache/brpc/pull/2949)
   
   
   Problem Summary:
   
    Under high throughput, a race condition in brpc's bvar subsystem causes a 
SIGSEGV during take_sample. When a thread's TLS Agent destructs after its owning
     AgentCombiner (Reducer, IntRecorder, or Percentile) has already been 
freed, the agent dereferences a dangling raw pointer in its destructor via
     combiner->commit_and_erase(this).
   
   
   The fix (backport of apache/brpc#2949) replaces the raw back-pointer from 
Agent to AgentCombiner with a weak_ptr, and makes the owning classes hold the 
combiner via
     shared_ptr. The agent destructor now calls combiner.lock() — if the 
combiner is already destroyed, lock() returns null and the destructor safely 
no-ops, eliminating
     the use-after-free.
   
   ### Release note
   
   None
   
   ### Check List (For Author)
   
   - Test <!-- At least one of them must be included. -->
       - [ ] Regression test
       - [x] Unit Test
       - [ ] Manual test (add detailed scripts or steps below)
       - [ ] No need to test or manual test. Explain why:
           - [ ] This is a refactor/code format and no logic has been changed.
           - [ ] Previous test can cover this change.
           - [ ] No code files have been changed.
           - [ ] Other reason <!-- Add your reason?  -->
   
   - Behavior changed:
       - [x] No.
       - [ ] Yes. <!-- Explain the behavior change -->
   
   - Does this need documentation?
       - [x] No.
       - [ ] Yes. <!-- Add document PR link here. eg: 
https://github.com/apache/doris-website/pull/1214 -->
   
   ### Check List (For Reviewer who merge this PR)
   
   - [ ] Confirm the release note
   - [ ] Confirm test cases
   - [ ] Confirm document
   - [ ] Add branch pick label <!-- Add branch pick label that this PR should 
merge into -->
   
   


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