BitoAgent commented on PR #31095:
URL: https://github.com/apache/doris/pull/31095#issuecomment-1954926731
## PR Run Status
- **AI Based Review:** Successful
- **Static Analysis:** Failure - Failed to execute static code analysis
using FBinfer.
## PR Analysis
- **Main theme:** Implementing thread-safety in routine load job operations
to avoid editLog out of order issues.
- **PR summary:** This PR addresses a critical bug where concurrent updates
to routine load jobs could lead to a NullPointerException due to out-of-order
editLog entries. By introducing locks around job state changes, the PR aims to
ensure atomicity in job metadata recording and editLog persistence, thus
preventing the crash.
- **Type of PR:** Bug fix
- **Score:** 85
- **Relevant tests added:** No
- **Estimated effort to review:** 3
The changes are straightforward with the introduction of locking mechanisms
around critical sections. However, the impact of these changes on performance
and potential deadlock scenarios needs careful consideration.
## PR Feedback
- **General suggestions:** The approach taken to address the concurrency
issue by adding locks around state-changing operations is sound. However, it's
crucial to consider the performance implications of introducing locks,
especially in high-throughput environments. Additionally, the PR lacks tests
that specifically cover the scenarios of concurrent job updates, which are
essential to ensure the robustness of the fix. It would be beneficial to
include performance benchmarks and tests that simulate concurrent updates to
validate the solution comprehensively.
## Code feedback
## file:
fe/fe-core/src/main/java/org/apache/doris/load/routineload/RoutineLoadManager.java
- **Suggestions:**
1. Consider using more granular locks or lock-free mechanisms to mitigate
potential performance bottlenecks. [important] **Relevant line**:In
fe/fe-core/src/main/java/org/apache/doris/load/routineload/RoutineLoadManager.java
at line 317
```
+ readLock();
```
2. Add specific unit tests to simulate concurrent job updates and ensure
that the locking mechanism effectively prevents out-of-order editLogs.
[important] **Relevant line**:In
fe/fe-core/src/main/java/org/apache/doris/load/routineload/RoutineLoadManager.java
at line 317
```
+ readLock();
```
3. Ensure that all paths that acquire locks are paired with a finally block
to guarantee the release of the lock, preventing potential deadlocks.
[important] **Relevant line**:In
fe/fe-core/src/main/java/org/apache/doris/load/routineload/RoutineLoadManager.java
at line 317
```
+ readLock();
```
4. Evaluate the necessity of read-write locks versus mutual exclusion locks
based on the actual read/write ratio to optimize concurrency control. [medium]
**Relevant line**:In
fe/fe-core/src/main/java/org/apache/doris/load/routineload/RoutineLoadManager.java
at line 317
```
+ readLock();
```
5. Review and possibly increase the test coverage for the
RoutineLoadManager class to include scenarios that were not previously
considered, such as concurrent access and potential race conditions.
[important] **Relevant line**:In
fe/fe-core/src/main/java/org/apache/doris/load/routineload/RoutineLoadManager.java
at line 317
```
+ readLock();
```
6. Consider the impact of locking on the overall system performance,
especially if the routine load job operations are frequent and concurrent.
Profiling and load testing should be conducted to assess the impact. [medium]
**Relevant line**:In
fe/fe-core/src/main/java/org/apache/doris/load/routineload/RoutineLoadManager.java
at line 317
```
+ readLock();
```
7. Investigate alternative concurrency control mechanisms that could offer
better performance or simplicity, such as optimistic concurrency controls or
using concurrent data structures. [medium] **Relevant line**:In
fe/fe-core/src/main/java/org/apache/doris/load/routineload/RoutineLoadManager.java
at line 317
```
+ readLock();
```
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