stinger1206 opened a new pull request, #67276:
URL: https://github.com/apache/doris/pull/67276
### What problem does this PR solve?
Issue Number: close #66895
Related PR: apache/brpc#3291
Problem Summary:
Follow-up to #64040 (backport of apache/brpc#2949). That fix made
`Agent::~Agent()`
safe by using a `weak_ptr` for `Agent::combiner`, but `~AgentCombiner()`
still calls
`clear_all_agents()`. When the last `shared_ptr` to the combiner is released
while
another thread is exiting, the TLS agents' `weak_ptr`s are already expired:
`~Agent`
skips `commit_and_erase()` and leaves its `LinkNode` in `_agents`, then the
`ThreadBlock` is freed - and `clear_all_agents()` walks that freed TLS
storage,
causing a heap-use-after-free. In production this shows up as SIGSEGV in
`bvar::SeriesSampler::take_sample` (#66895).
Fix: port apache/brpc#3291 - `~AgentCombiner()` no longer traverses
`_agents`.
This is safe: `butil::LinkNode` has a trivial destructor and is never
dereferenced
when the list is torn down, and surviving agents observe `combiner.expired()
== true`
in `~Agent` and skip `commit_and_erase()`. There is no memory leak: agents
are freed
together with their `ThreadBlock` at thread exit. This closes the gap that
was
flagged during review of #64040.
### Release note
None
### Check List (For Author)
- Test
- [ ] Regression test
- [ ] Unit Test
- [x] Manual test (add detailed scripts or steps below)
- [ ] No need to test or manual test. Explain why:
- Behavior changed:
- [x] No.
- [ ] Yes.
- Does this need documentation?
- [x] No.
- [ ] Yes.
Manual test:
1. Applied the patch on top of the existing
`brpc-1.4.0-fix-agent-combiner-thread-safety.patch` and rebuilt brpc 1.4.0
thirdparty + BE (4.1.3-based image).
2. Ran the same workload that previously triggered the crashes in #66895:
sustained high-EPS stream load while rewriting a ~40B-row table from
storage format V2 to V3 on the affected production cluster
(compute-storage coupled mode, 6 BE nodes, Kubernetes).
3. Before the fix: BEs crashed with SIGSEGV in
`bvar::SeriesSampler::take_sample` (two BEs independently, see issue).
After the fix: the production cluster has been running stable for 2 days
with the patch applied - no recurrence of the SIGSEGV.
### Check List (For Reviewer who merge this PR)
- Confirm the release note
- Confirm test cases
- Confirm document
- Add branch pick label
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