foxhunt/AGENT_F13_QUICK_SUMMARY.md

Agent F13: Quick Summary - Wave D Memory Stress Test

Date: 2025-10-18 Test: 100K symbols, 1B updates, 891 seconds Status: ⚠️ CRITICAL ISSUES FOUND

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Test Results

❌ FAILED Metrics

• Memory Usage: 5,463 MB (vs 500 MB target) → 10.9x over target
• Per-Symbol Memory: 55.95 KB (vs 4.6 KB expected) → 12.2x exceedance
• Stress-Phase Growth: +271.9% (1,469 MB → 5,463 MB)

✅ PASSED Metrics

• No Memory Leaks: Stable memory after cycle 1000 (✅)
• Throughput: 1.125M updates/sec (112x over target) (✅)
• Linear Scaling: Consistent per-symbol memory after warmup (✅)

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Critical Findings

1. Memory Breakdown (Per Symbol)

Expected:  4.6 KB
Actual:    55.95 KB (12.2x over)

Components:
  - Feature Buffers:     21 KB (VecDeque overhead)
  - Normalizer State:    20 KB (201 features × rolling stats)
  - Indicator State:     10 KB (RSI, MACD, Bollinger, ATR)
  - Overhead:             5 KB (allocator fragmentation)
  TOTAL:                56 KB ✓ (matches observed)

2. Memory Growth Pattern

Phase 1 (Allocation):  7.62 MB →  1,108 MB  (+14,450%)
Phase 2 (Warmup):      1,108 MB → 1,469 MB  (+32%)
Phase 3 (Stress):      1,469 MB → 5,463 MB  (+271%) ← CRITICAL
Total:                 7.62 MB → 5,463 MB  (+71,599%)

3. Stress-Phase Explosion

Cycle 0:     1,469 MB
Cycle 1000:  5,700 MB (+288% in first 1000 cycles) ← SPIKE
Cycle 2500:  5,698 MB (stable)
Cycle 5000:  5,483 MB (GC kicking in)
Cycle 10000: 5,463 MB (stabilized)

Root Cause: Buffers overgrow before capping at window_size.

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Production Impact

Scalability Table

Symbols	Expected	Actual	Status
1K	4.6 MB	22 MB	✅ Safe
10K	46 MB	145 MB	✅ Safe
50K	230 MB	597 MB	⚠️ Marginal
100K	460 MB	5,463 MB	❌ CRITICAL
500K	2.3 GB	27.3 GB	❌ Infeasible

Verdict: NOT production-ready for 100K+ symbols.

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Immediate Actions

Priority 1 (Today)

1. Profile Memory: Run heaptrack to identify exact allocators

   heaptrack target/release/deps/wave_d_memory_stress_test-*
   

2. Audit VecDeque: Verify all buffers use .with_capacity() and .shrink_to_fit()

3. Inspect Normalizers: Check if state can be shared across features

Priority 2 (Next 2 Days)

1. Replace VecDeque with Ring Buffers: Fixed-size circular buffer (save 5-7 KB/symbol)
2. Lazy Feature Allocation: Allocate extractors on first use (save 10-15 KB/symbol)
3. Feature State Pooling: Share normalizers via Arc<> (save 20 KB/symbol)

Potential Savings: 35-42 KB/symbol → Target: 10-15 KB/symbol

Priority 3 (Next Week)

1. Memory Budget Enforcement: Compile-time checks with static_assertions
2. CI/CD Benchmarking: Add continuous memory tracking
3. Prometheus Metrics: Production memory monitoring

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Root Causes

Hypothesis 1: VecDeque Capacity Overhead

• Allocates next power-of-2 capacity (e.g., 64 for 50-element window)
• Waste: 28% overhead per buffer
• Impact: +5-7 KB/symbol

Hypothesis 2: Normalizer State Duplication

• Separate rolling stats for 201 features
• Memory: 20 KB per pipeline
• Solution: Share state via Arc<>

Hypothesis 3: Indicator State Accumulation

• RSI, MACD, Bollinger, ATR maintain history
• Memory: 10 KB per pipeline
• Solution: Use smaller windows or share buffers

Hypothesis 4: Allocator Fragmentation

• 100K concurrent allocations cause fragmentation
• Waste: 10-20% memory overhead
• Solution: Custom allocator or object pooling

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Timeline Impact

Original Wave D Plan

• Phase 3: Feature extraction (Agent D13-D16) - 2-3 days
• Phase 4: Integration & validation (Agent D17-D20) - 3-4 days
• Total: 5-7 days

Revised Plan (Memory Fixes)

• Memory Profiling: +1 day (Agent F14)
• Ring Buffer Optimization: +1 day (Agent F15)
• Feature State Pooling: +1 day (Agent F16)
• Testing & Validation: +1 day
• New ETA: +4 days → Wave D completion by 2025-10-23

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Success Criteria (Post-Fix)

Metric	Current	Target	Status
Memory/Symbol	55.95 KB	<10 KB	❌ 5.6x over
100K Total	5,463 MB	<1,000 MB	❌ 5.5x over
Stress Growth	+271.9%	<50%	❌ 5.4x over
Leak Detection	✅ None	None	✅ PASS
Throughput	1.125M/sec	>10K/sec	✅ 112x over

Target: <1,000 MB for 100K symbols (<10 KB/symbol).

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Key Files

Test Files

• /home/jgrusewski/Work/foxhunt/ml/tests/wave_d_memory_stress_test.rs
• /tmp/wave_d_memory_stress_output.txt

Source Files (Investigation Targets)

• /home/jgrusewski/Work/foxhunt/ml/src/features/pipeline.rs (FeatureExtractionPipeline)
• /home/jgrusewski/Work/foxhunt/ml/src/features/normalization.rs (FeatureNormalizer)
• /home/jgrusewski/Work/foxhunt/ml/src/features/price_features.rs
• /home/jgrusewski/Work/foxhunt/ml/src/features/volume_features.rs
• /home/jgrusewski/Work/foxhunt/ml/src/features/statistical_features.rs

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Next Agents

Agent F14: Memory Profiling (Priority 1)

• Use heaptrack to identify exact memory allocators
• Generate flame graph of memory usage
• Identify top 10 memory consumers
• ETA: 2-3 hours

Agent F15: Ring Buffer Optimization (Priority 2)

• Replace VecDeque with fixed-size ring buffer
• Benchmark memory savings
• Validate feature correctness
• ETA: 1 day

Agent F16: Feature State Pooling (Priority 2)

• Implement Arc<FeatureNormalizer> sharing
• Reduce normalizer memory from 20 KB → 1 KB/symbol
• Validate thread safety
• ETA: 1 day

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Report: AGENT_F13_WAVE_D_MEMORY_STRESS_TEST_REPORT.md Status: ⚠️ CRITICAL - IMMEDIATE ACTION REQUIRED