yujun777 opened a new pull request, #64958:
URL: https://github.com/apache/doris/pull/64958
## Problem
Fixes DORIS-26669.
ALTER MTMV REFRESH ON COMMIT calls `alterJob()` which does `dropJob()` +
`createJob()`, creating a new MTMVJob instance with a new
ReentrantReadWriteLock. If the CREATE MTMV immediate build task is still
running under the old job's writeLock, the new on-commit task can acquire the
new job's writeLock concurrently, causing two refresh tasks to operate on the
same MTMV simultaneously.
This race triggers "partition not found" when the on-commit task reads
partition metadata via
`UpdateMvByPartitionCommand.constructTableWithPredicates()`, while the
immediate build task is in the middle of replacing partitions.
## Root Cause
- `alterJob()` drops the old job and creates a new one
- The new job has a brand new `ReentrantReadWriteLock` instance
- `MTMVTask.runTask()` acquires the writeLock from `getJobOrJobException()`
- After drop+create, `getJobOrJobException()` returns the new job with a
different lock
- Two tasks can hold two different locks → no mutual exclusion
## Fix
In `alterJob()`, acquire the existing job's writeLock before drop+create,
ensuring all running tasks complete before the job is rebuilt. This serializes
the alter with any in-flight tasks using the same lock instance.
## Change
Single file:
`fe/fe-core/src/main/java/org/apache/doris/mtmv/MTMVJobManager.java`
```java
public void alterJob(MTMV mtmv, boolean isReplay) {
MTMVJob oldJob = getJobByMTMV(mtmv);
if (!isReplay && oldJob != null) {
oldJob.writeLock(); // block until running tasks complete
}
try {
dropJob(mtmv, isReplay);
createJob(mtmv, isReplay);
} finally {
if (!isReplay && oldJob != null) {
oldJob.writeUnlock();
}
}
}
```
- No deadlock risk: lock ordering is always PER-JOB → GLOBAL, no reverse path
- Replay path (`isReplay=true`) unchanged
- Null-safe on `oldJob`
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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