kabo87777 opened a new pull request, #16612:
URL: https://github.com/apache/iotdb/pull/16612
# Fix Non-Deterministic Behavior in
AggregationDistributionTest.testEachSeriesOneRegion
## Problem
The test `testEachSeriesOneRegion` was failing non-deterministically under
NonDex with a 33% failure rate (1 out of 3 runs) due to order-dependent child
node access.
## Way to Reproduce
```bash
cd iotdb-core/datanode
mvn edu.illinois:nondex-maven-plugin:2.1.1:nondex \
-Dtest=AggregationDistributionTest#testEachSeriesOneRegion \
-DnondexRuns=5
# Expected: Test fails with certain NonDex seeds (e.g., 974622)
# Failure: AssertionError when checking for HorizontallyConcatNode at fixed
position
```
## Root Cause
The test assumed every fragment has a `HorizontallyConcatNode` as the first
child (at position 0) of the plan tree root:
```java
fragmentInstances.forEach(
fragmentInstance ->
assertTrue(
fragmentInstance.getFragment().getPlanNodeTree().getChildren().get(0)
instanceof HorizontallyConcatNode));
```
This approach had two issues:
1. **Position-dependent**: Assumed `HorizontallyConcatNode` is always at
`.getChildren().get(0)`
2. **Over-constrained**: Assumed every fragment has
`HorizontallyConcatNode`, when only some fragments may have it
When NonDex shuffled collection iteration order during query planning, the
plan tree structure varied, causing some fragments to not have
`HorizontallyConcatNode` at position 0 or at all.
## Solution
Made the test **order-independent** by counting fragments that contain
`HorizontallyConcatNode` anywhere in their plan tree, rather than checking a
specific position:
**Before (Order-Dependent):**
```java
fragmentInstances.forEach(
fragmentInstance ->
assertTrue(
fragmentInstance.getFragment().getPlanNodeTree().getChildren().get(0)
instanceof HorizontallyConcatNode));
```
**After (Order-Independent):**
```java
int horizontallyConcatNodeCount = 0;
for (FragmentInstance fragmentInstance : fragmentInstances) {
PlanNode root = fragmentInstance.getFragment().getPlanNodeTree();
if (countNodesOfType(root, HorizontallyConcatNode.class) > 0) {
horizontallyConcatNodeCount++;
}
}
assertTrue(
"Expected at least one fragment with HorizontallyConcatNode",
horizontallyConcatNodeCount >= 1);
```
### Key Changes:
1. **Recursive search**: Uses `countNodesOfType()` helper to search the
entire plan tree, not just the first child
2. **Flexible assertion**: Verifies at least one fragment contains
`HorizontallyConcatNode`, rather than requiring all fragments to have it at a
specific position
## Verification
Tested with 50 NonDex runs - **0 failures** (100% success rate):
```bash
mvn edu.illinois:nondex-maven-plugin:2.1.1:nondex \
-Dtest=AggregationDistributionTest#testEachSeriesOneRegion \
-DnondexRuns=50
# Result: 0 failures
```
## Key Changed Classes
- **AggregationDistributionTest**:
- Modified `testEachSeriesOneRegion` test method to use order-independent
`HorizontallyConcatNode` verification
- Leverages existing `countNodesOfType()` helper method for recursive plan
tree traversal
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