perf: add aggregate report for 4.2.25 and 4.2.26 [ci skip]

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russell@unturf.com 2026-01-24 18:14:26 -05:00
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# UN Inception: Aggregated Performance Analysis
**Analysis Date:** 1769296457.6742005
**Reports Analyzed:** 4.2.25, 4.2.26
---
## Executive Summary
Analysis of 2 performance reports reveals **significant variance** in execution metrics across releases. Different languages rank as slowest/fastest in different runs, indicating **non-deterministic execution patterns** likely caused by:
1. **Orchestrator placement on CPU-bound pool** (not an SRE best practice)
2. **Resource contention** between the orchestrator & test jobs
3. **Undefined or exceeded concurrency limits**
4. **Non-deterministic scheduling** of the matrix jobs
---
## Key Findings
### 1. Extreme Metric Variance
| Release | Avg Duration | Slowest | Fastest | Change from Previous |
|---------|--------------|---------|---------|----------------------|
| 4.2.25 | 97s | fortran (151s) | bash (58s) | baseline |
| 4.2.26 | 78s | cpp (130s) | python (25s) | -19s (-19.6%) |
**Observation:** Average duration increased **0.0%** from 0s to 0s.
This **2-3x variance** is NOT normal for identical workloads. Indicates:
- Orchestrator fighting for CPU with test jobs
- Tests running in different order each time
- No consistent resource allocation
---
### 2. Unstable Language Rankings
The same language changes dramatically in rank between runs:
**FORTRAN:**
- 4.2.25: 151s
- 4.2.26: 59s
- **Range:** 59s → 151s (155.9% variance)
**FSHARP:**
- 4.2.25: 102s
- 4.2.26: 34s
- **Range:** 34s → 102s (200.0% variance)
**GO:**
- 4.2.25: 130s
- 4.2.26: 62s
- **Range:** 62s → 130s (109.7% variance)
**AWK:**
- 4.2.25: 140s
- 4.2.26: 78s
- **Range:** 78s → 140s (79.5% variance)
**JULIA:**
- 4.2.25: 113s
- 4.2.26: 52s
- **Range:** 52s → 113s (117.3% variance)
---
### 3. Execution Order Non-Determinism
**Fastest Languages by Run:**
4.2.25: bash, powershell, forth, r, prolog
4.2.26: python, fsharp, ocaml, haskell, julia
**Slowest Languages by Run:**
4.2.25: fortran, crystal, perl, awk, cpp
4.2.26: cpp, raku, cobol, javascript, ruby
**Conclusion:** No consistent "fast" or "slow" languages across runs. This proves:
- Execution order is random or system-dependent
- Resource availability varies dramatically
- Each run experiences different contention patterns
---
## The Orchestrator Problem: DevOps 101
### Why This Matters
Running the orchestrator on a **CPU-bound pool node** violates fundamental SRE principles:
```
❌ BAD: [ORCHESTRATOR] + [TEST JOB 1] + [TEST JOB 2] ... on same CPU pool
✅ GOOD: [ORCHESTRATOR] on dedicated node, [TESTS] on separate pool
```
**What happens:**
1. Orchestrator needs CPU to schedule/coordinate jobs
2. Test jobs need CPU to run
3. Both compete for limited CPU cycles
4. Context switching & cache thrashing = unpredictable timing
5. Matrix generation order becomes random as scheduler equilibrates
### Why It's Fun for Chaos Engineering
From a chaos testing perspective, this setup is **perfect**:
- Reproduces real-world resource contention
- Tests system behavior under adversarial conditions
- Reveals race conditions & timing bugs
- No two runs are identical (true chaos)
**But for production CI/CD?** It's a nightmare for:
- Performance benchmarking
- SLA guarantees
- Debug reproducibility
- Billing/cost predictability
---
## Concurrency Hypothesis
### Theory: Matrix Hydra Execution Limits
Given 42 languages with 15 tests each, if there were a **concurrency limit**, we'd expect:
**Observed avg duration:** 33-70s
**If truly serialized (1 job at a time):** ~500s minimum
**If unlimited parallel:** ~50-70s
This suggests jobs run in **parallel batches**, but the batch size varies:
#### Possible Concurrency Models:
1. **Kubernetes Executor (default 32-64 parallel):** Each release has different load
2. **GitLab runner queue saturation:** Some runs hit limits, others don't
3. **Node CPU throttling:** Kubernetes QoS class limits being applied
4. **No explicit limit, but OS scheduler bottleneck:** ~64 thread context limit
### Evidence from Timing Patterns
If concurrency was fixed at N parallel jobs:
- `Total time = ceiling(42 / N) * (average job time)`
- For 4.2.0 (33s avg): ~42 concurrent or very efficient scheduling
- For 4.2.3 (63s avg): ~20 concurrent (slower overall, more contention)
- For 4.2.4 (70s avg): ~18 concurrent (even more contention)
**Implication:** Concurrency limit is either:
- **Dynamic** (based on available resources)
- **Not enforced** (unlimited, but OS scheduler creates natural limit)
- **Degrading** (orchestrator consuming more CPU over versions)
---
## Detailed Language Analysis
### Most Variable Languages
FORTRAN: 59s → 151s (+155.9%)
FSHARP: 34s → 102s (+200.0%)
GO: 62s → 130s (+109.7%)
AWK: 78s → 140s (+79.5%)
JULIA: 52s → 113s (+117.3%)
DART: 52s → 111s (+113.5%)
CRYSTAL: 89s → 145s (+62.9%)
ZIG: 55s → 108s (+96.4%)
HASKELL: 51s → 103s (+102.0%)
KOTLIN: 59s → 110s (+86.4%)
These languages are most affected by resource contention. Likely reasons:
- **Dynamic languages** (Python, Ruby, JavaScript): Startup time varies with GC/JIT
- **Compiled languages with heavy linking** (C++, Rust): Linker contention
- **Language VMs** (Java, Elixir): VM startup sensitive to system load
---
## Recommendations
### For Production CI/CD
1. **Separate orchestrator from compute pool**
- Dedicated small node for GitLab runner/orchestrator
- Dedicated larger pool for test jobs
- Isolate using Kubernetes node affinity or taints
2. **Set explicit concurrency limits**
```yaml
# GitLab .gitlab-ci.yml
trigger-test-matrix:
parallel: 32 # Fixed concurrency
max_parallel_builds: 32
```
3. **Monitor resource usage**
- CPU utilization on runner nodes
- Memory pressure & swap activity
- Context switch rates
4. **Implement backpressure**
- Queue jobs when pool is full
- Implement exponential backoff for retries
- Monitor orchestrator health separately
### For Chaos Engineering
This setup is **excellent** for:
- Testing flaky test detection systems
- Validating retry logic
- Measuring performance under contention
- Finding race conditions in test infrastructure
Keep it as-is for stress testing, but in separate test environment.
---
## Raw Data: Language Variance Table
| Language | Min (s) | Max (s) | Avg (s) | Range (s) | Variance % |
|----------|---------|---------|---------|-----------|------------|
| PYTHON | 25 | 76 | 50.5 | 51 | 204.0% |
| FSHARP | 34 | 102 | 68.0 | 68 | 200.0% |
| FORTRAN | 59 | 151 | 105.0 | 92 | 155.9% |
| JULIA | 52 | 113 | 82.5 | 61 | 117.3% |
| DART | 52 | 111 | 81.5 | 59 | 113.5% |
| GO | 62 | 130 | 96.0 | 68 | 109.7% |
| OCAML | 49 | 99 | 74.0 | 50 | 102.0% |
| HASKELL | 51 | 103 | 77.0 | 52 | 102.0% |
| ZIG | 55 | 108 | 81.5 | 53 | 96.4% |
| NIM | 53 | 100 | 76.5 | 47 | 88.7% |
| KOTLIN | 59 | 110 | 84.5 | 51 | 86.4% |
| D | 58 | 107 | 82.5 | 49 | 84.5% |
| V | 54 | 97 | 75.5 | 43 | 79.6% |
| AWK | 78 | 140 | 109.0 | 62 | 79.5% |
| BASH | 58 | 101 | 79.5 | 43 | 74.1% |
| OBJC | 54 | 93 | 73.5 | 39 | 72.2% |
| CRYSTAL | 89 | 145 | 117.0 | 56 | 62.9% |
| RUST | 63 | 99 | 81.0 | 36 | 57.1% |
| JAVASCRIPT | 74 | 114 | 94.0 | 40 | 54.1% |
| PHP | 73 | 107 | 90.0 | 34 | 46.6% |
---
## Visualizations
### Duration Degradation Trend
![Duration Trend](aggregated-duration-trend.png)
**Shows:** Average test duration increasing 2.1x from 4.2.0 → 4.2.4
### Language Variance Heatmap
![Language Variance](aggregated-language-variance.png)
**Shows:** Top 15 most unstable languages, with Elixir, TCL, and C showing >300% variance
### Ranking Instability
![Ranking Changes](aggregated-ranking-changes.png)
**Shows:** The same languages moving dramatically in performance rankings across releases
---
## Conclusion
The variance in performance metrics across these three releases is **not random noise**—it's a symptom of **architectural misplacement**.
The orchestrator running on the CPU-bound pool creates **cascading effects**:
1. Reduced CPU available for jobs → slower execution
2. Random scheduling order → different languages hit different contention levels
3. Each run has unique timing → metrics become meaningless for benchmarking
**For SRE/DevOps:** This is textbook example of why infrastructure placement matters.
**For Chaos Engineering:** This is gold—true adversarial execution.
The solution is simple: **separate the orchestrator from the compute pool**.
---
## Reproducibility & Methodology
### Pipeline Overview
This aggregated report is generated from individual performance reports collected during CI/CD runs. The pipeline combines data analysis, statistical variance calculation, and visualization rendering.
**Architecture:**
```
Individual Reports → Aggregation Script → Chart Generation (via UN) → Final Report
(perf.json) (Python) (matplotlib) (Markdown)
```
### Data Sources
**Input Files:**
- `reports/4.2.25/perf.json` - 681 tests, generated 2026-01-24T21:04:06Z
- `reports/4.2.26/perf.json` - 661 tests, generated 2026-01-24T21:08:03Z
Each `perf.json` contains:
- Pipeline metadata (tag, timestamp, pipeline IDs)
- Summary statistics (avg, min, max durations)
- Per-language results (42 languages × ~15 tests each)
- Queue times & execution durations
**Data Collection:**
1. GitLab CI triggers test matrix (42 languages in parallel)
2. Each language job reports timing via GitLab API
3. `scripts/generate-perf-report.sh` queries API & generates `perf.json`
4. Report committed to `reports/{TAG}/` directory
### Analysis Pipeline
**Step 1: Variance Analysis** (`scripts/aggregate-performance-reports.py`)
```python
# Load all reports
for version_dir in Path('reports').iterdir():
reports[version] = json.loads((version_dir / 'perf.json').read_text())
# Extract language timings
for version, perf_data in reports.items():
for lang_entry in perf_data['languages']:
language_timings[version][lang_entry['language']] = lang_entry['duration_seconds']
# Calculate variance per language
for lang in all_languages:
durations = [language_timings[v][lang] for v in versions if lang in language_timings[v]]
percent_variance = ((max(durations) - min(durations)) / min(durations) * 100)
```
**Step 2: Chart Generation** (`scripts/generate-aggregated-charts.py`)
Charts are generated using **matplotlib inside UN sandbox** (not local environment):
```bash
# Copy reports with version-tagged names
cp reports/4.2.0/perf.json perf-4.2.0.json
cp reports/4.2.3/perf.json perf-4.2.3.json
cp reports/4.2.4/perf.json perf-4.2.4.json
# Execute chart generation via UN (includes matplotlib)
build/un -a \
-f perf-4.2.0.json \
-f perf-4.2.3.json \
-f perf-4.2.4.json \
scripts/generate-aggregated-charts.py
# Artifacts returned: *.png files
```
**Why UN for Charts?**
- Matplotlib not installed locally (by design)
- UN sandbox provides pre-configured Python environment with matplotlib
- Ensures reproducibility across different machines
- Same approach used in GitLab CI/CD pipeline
**Step 3: Report Generation**
```bash
# Generate markdown report (no matplotlib needed locally)
python3 scripts/aggregate-performance-reports.py reports AGGREGATED-PERFORMANCE.md
```
### Reproducing This Report
**Prerequisites:**
- Git repository checked out
- `build/un` binary (UN Inception CLI client)
- Python 3.x (for report generation, not charts)
- Access to `reports/` directory with historical data
**Command:**
```bash
make perf-aggregate-report
```
**Or manually:**
```bash
# Step 1: Generate charts
cp reports/4.2.0/perf.json perf-4.2.0.json
cp reports/4.2.3/perf.json perf-4.2.3.json
cp reports/4.2.4/perf.json perf-4.2.4.json
build/un -a -f perf-4.2.0.json -f perf-4.2.3.json -f perf-4.2.4.json scripts/generate-aggregated-charts.py
rm -f perf-*.json
mv *.png reports/
# Step 2: Generate markdown report
python3 scripts/aggregate-performance-reports.py reports AGGREGATED-PERFORMANCE.md
```
### Stepping Back in Time
To regenerate this report with historical data:
1. **Checkout the specific commit:**
```bash
git checkout <commit-sha>
```
2. **Verify reports exist:**
```bash
ls -la reports/4.2.0/perf.json
ls -la reports/4.2.3/perf.json
ls -la reports/4.2.4/perf.json
```
3. **Run analysis:**
```bash
make perf-aggregate-report
```
### CI/CD Integration
This report auto-generates on release tags via GitLab CI:
```yaml
perf-aggregate-report:
stage: report
needs: [perf-report]
script:
- echo "Generating aggregated analysis..."
- cp reports/4.2.0/perf.json perf-4.2.0.json
- cp reports/4.2.3/perf.json perf-4.2.3.json
- cp reports/4.2.4/perf.json perf-4.2.4.json
- build/un -a -f perf-4.2.0.json -f perf-4.2.3.json -f perf-4.2.4.json scripts/generate-aggregated-charts.py
- python3 scripts/aggregate-performance-reports.py reports AGGREGATED-PERFORMANCE.md
- git add reports/ AGGREGATED-PERFORMANCE.md
- git commit -m "perf: Update aggregated performance analysis [ci skip]"
- git push origin main
rules:
- if: '$CI_COMMIT_TAG =~ /^\d+\.\d+\.\d+$/'
```
**When new release tagged:** Pipeline automatically updates aggregated report with new data point.
### Statistical Methods
**Variance Calculation:**
- Per-language min/max/avg across all releases
- Percent variance: `((max - min) / min) * 100`
- Languages with <2 data points excluded
**Ranking Analysis:**
- Languages sorted by duration per release
- Top 10 slowest tracked across releases
- Ranking position changes indicate non-determinism
**Concurrency Estimation:**
- Average duration vs theoretical serialized time
- Estimated parallel capacity: `ceiling(42 langs / avg_duration) * per_job_time`
- Variance suggests dynamic (not fixed) concurrency
### Tools & Dependencies
**Local Environment:**
- Python 3.x (standard library only)
- `build/un` - UN Inception CLI
- Git (for version control)
- Bash (for scripting)
**UN Sandbox Environment:**
- Python 3.x with matplotlib, numpy
- Pre-configured visualization environment
- Isolated execution (no local dependencies)
**GitLab CI:**
- GitLab Runner with `build` tag
- Environment variables: `UNSANDBOX_PUBLIC_KEY`, `UNSANDBOX_SECRET_KEY`
- Deploy key for auto-commit
### Data Integrity
**Validation:**
- JSON schema validation on input files
- Version tag format validation (`X.Y.Z`)
- Minimum 2 releases required for variance analysis
**Timestamps:**
- All reports include generation timestamp
- Commit history provides audit trail
- CI pipeline IDs link back to source runs
### Contact & Questions
For questions about this methodology or to report issues:
- Repository: `git.unturf.com/engineering/unturf/un-inception`
- Methodology issues: Open issue with `[methodology]` tag
- Data integrity concerns: Check commit history & CI pipeline logs
---
**Generated by UN Inception Performance Analysis Pipeline**
**Analysis Date:** 2026-01-24T18:14:22.062723
**Report Version:** 1.0.0