daguimu opened a new pull request, #10211:
URL: https://github.com/apache/rocketmq/pull/10211
## Problem
In `ConsumeQueue.correctMinOffset()`, the size check at line 616 only guards
against completely empty buffers (`result.getSize() == 0`). When a consume
queue mapped file contains a partially written record (1-19 bytes, less than
`CQ_STORE_UNIT_SIZE` = 20), the subsequent `buffer.getLong()` call throws
`BufferUnderflowException`.
This can happen when:
1. The last mapped file in a consume queue has a partially written record
due to async flush
2. CommitLog messages are lost during restart (async-flush + sync-master)
3. The broker does not truncate the incomplete record during recovery
## Root Cause
The check `result.getSize() == 0` does not cover the case where
`result.getSize()` is between 1 and 19 (less than one complete CQ unit of 20
bytes). A partial record cannot be meaningfully processed.
Note: PR #10109 previously added a guard for the last mapped file check
(lines 564-570), which resolved the main startup crash. This PR addresses the
remaining edge case in the binary search section where a partially written
record could still cause a `BufferUnderflowException`.
## Fix
Changed the size check from:
```java
if (result.getSize() == 0) {
```
to:
```java
if (result.getSize() < ConsumeQueue.CQ_STORE_UNIT_SIZE) {
```
This properly handles both empty buffers and incomplete records.
## Tests Added
No new tests needed — existing `ConsumeQueueTest` (13 tests covering
`correctMinOffset` with various offset scenarios) all pass. The fix is a
one-line defensive check improvement.
## Impact
- Prevents `BufferUnderflowException` on partially written consume queue
records
- No behavioral change for normal consume queues (all valid records are >=
20 bytes)
- Minimal, single-line change with no risk of side effects
Fixes #9728
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