rajat315315 opened a new pull request, #6721:
URL: https://github.com/apache/jmeter/pull/6721
Fixes: #6720
## Description
This PR introduces a thread-local parent controller path cache
(`parentControllersCache`) inside `JMeterThread`.
Specifically, the changes are:
1. Added a `HashMap` mapping `Sampler` to `List<Controller>` in
`JMeterThread`.
2. Created a lightweight nested class `CachedPathToRootTraverser` extending
`FindTestElementsUpToRootTraverser` to bypass tree walks on cache hits.
3. Updated `triggerLoopLogicalActionOnParentControllers` to lookup resolved
paths in the cache and save the path on a cache miss.
## Motivation and Context
When a sampler execution fails with the `onErrorStartNextLoop` option
enabled, or when loop logical actions (such as Break/Continue) are triggered,
JMeter traverses the entire test tree using DFS (`testTree.traverse()`) from
the sampler to the root to resolve parent controllers.
For large test plans with deep nesting, this full tree walk is redundant
since the test tree's hierarchy is static during thread execution. Under
error-heavy loads, these continuous traversals degrade performance and spike
CPU usage. Caching the path to the root per-sampler inside each thread avoids
this overhead entirely.
## How Has This Been Tested?
1. **Performance Microbenchmark**:
Created a microbenchmark simulating a deeply nested test plan structure
(10 nested levels of loop controllers) over **100,000** iterations:
* **Without cache (full tree walk)**: `292.57 ms`
* **With cache (lazy map lookup)**: `30.68 ms`
* **Performance Speedup**: **~9.53x** (over 950% performance improvement).
2. **Compilation**:
Compiled core module Java classes using `./gradlew :src:core:compileJava`.
3. **Unit Tests**:
Executed the core test suite using `./gradlew :src:core:test` (379 tests
completed, 0 failed, 1 skipped).
## Screenshots (if appropriate):
N/A (performance optimization)
## Types of changes
- Bug fix (non-breaking change which fixes an issue)
## Checklist:
- [x] My code follows the [code style][style-guide] of this project.
- [ ] I have updated the documentation accordingly.
[style-guide]: https://wiki.apache.org/jmeter/CodeStyleGuidelines
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