- CRITICAL FIX: Python output buffering caused silent failure - Solution: python3 -u flag for unbuffered output - 70% CPU optimization: int(cpu_count() * 0.7) = 22-24 cores per server - Current state: 47 workers, load ~22 per server, 16.3 hour timeline - System operational since Dec 1 22:50:32 - Expected completion: Dec 2 15:15
5.1 KiB
5.1 KiB
V9 Advanced Parameter Sweep - 70% CPU Deployment (Dec 1, 2025)
CRITICAL FIX: Python Output Buffering
Problem Discovered
After restart to apply 70% CPU optimization, system entered "silent failure" mode:
- Coordinator process running but producing ZERO output
- Log files completely empty (only "nohup: ignoring input")
- Workers not starting (0 processes, load 0.27)
- System appeared dead but was actually working
Root Cause
Python's default behavior buffers stdout/stderr. When running:
nohup python3 script.py > log 2>&1 &
Output is buffered in memory and not written to log file until buffer fills, process terminates, or explicit flush occurs.
Solution Implemented
# BEFORE (broken - buffered output):
nohup python3 v9_advanced_coordinator.py > log 2>&1 &
# AFTER (working - unbuffered output):
nohup python3 -u v9_advanced_coordinator.py > log 2>&1 &
The -u flag:
- Forces unbuffered stdout/stderr
- Output appears immediately in logs
- Enables real-time monitoring
- Critical for debugging and verification
70% CPU Optimization
Code Changes
v9_advanced_worker.py (lines 180-189):
# 70% CPU allocation
total_cores = cpu_count()
num_cores = max(1, int(total_cores * 0.7)) # 22-24 cores on 32-core system
print(f"Using {num_cores} of {total_cores} CPU cores (70% utilization)")
# Parallel processing
args_list = [(df, config) for config in configs]
with Pool(processes=num_cores) as pool:
results = pool.map(backtest_config_wrapper, args_list)
Performance Metrics
Current State (Dec 1, 2025 22:50+):
- Worker1: 24 processes, load 22.38, 99.9% CPU per process
- Worker2: 23 processes, load 22.20, 99.9% CPU per process
- Total: 47 worker processes across cluster
- CPU Utilization: ~70% per server (target achieved ✓)
- Load Average: Stable at ~22 per server
Timeline:
- Started: Dec 1, 2025 at 22:50:32
- Total Configs: 1,693,000 parameter combinations
- Estimated Time: 16.3 hours
- Expected Completion: Dec 2, 2025 at 15:15
Calculation:
- Effective cores: 47 × (70/93) = 35.4 cores
- Time per config: ~1.6 seconds (from benchmarks)
- Total time: 1,693,000 × 1.6s ÷ 35.4 cores ÷ 3600 = 16.3 hours
Deployment Status
Coordinator:
cd /home/icke/traderv4/cluster
nohup python3 -u v9_advanced_coordinator.py > coordinator_70pct_unbuffered.log 2>&1 &
- Running since: Dec 1, 22:50:32
- Log file: coordinator_70pct_unbuffered.log
- Monitoring interval: 60 seconds
- Status: 2 running, 1,691 pending, 0 completed
Workers:
- Worker1 (10.10.254.106):
/home/comprehensive_sweep/v9_advanced_worker.py - Worker2 (10.20.254.100):
/home/backtest_dual/backtest/v9_advanced_worker.py - Both deployed with 70% CPU configuration
- Both actively processing chunks
Database:
- Location:
/home/icke/traderv4/cluster/exploration.db - Table:
v9_advanced_chunks - Total: 1,693 chunks
- Status: pending|1691, running|2, completed|0
Verification Commands
Check system status:
# Database status
cd /home/icke/traderv4/cluster
sqlite3 exploration.db "SELECT status, COUNT(*) FROM v9_advanced_chunks GROUP BY status;"
# Worker processes
ssh root@10.10.254.106 "ps aux | grep [p]ython3 | grep v9_advanced_worker | wc -l && uptime"
ssh root@10.10.254.106 "ssh root@10.20.254.100 'ps aux | grep [p]ython3 | grep v9_advanced_worker | wc -l && uptime'"
# Coordinator logs
tail -20 coordinator_70pct_unbuffered.log
# Results files
ls -1 distributed_results/*.csv 2>/dev/null | wc -l
Expected results:
- Worker1: 24 processes, load ~22
- Worker2: 23 processes, load ~22
- Database: 2 running, decreasing pending count
- Results: Gradually appearing CSV files
Lessons Learned
- Always use
python3 -ufor background processes that need logging - Python buffering can cause silent failures - process runs but produces no visible output
- Verify logging works before declaring system operational
- Load average ~= number of cores at target utilization (22 load ≈ 70% of 32 cores)
- Multiprocessing at 99.9% CPU per process indicates optimal parallelization
Success Criteria (All Met ✓)
- ✅ Coordinator running with proper logging
- ✅ 70% CPU utilization (47 processes, load ~22 per server)
- ✅ Workers processing at 99.9% CPU each
- ✅ Database tracking chunk status correctly
- ✅ System stable and sustained operation
- ✅ Real-time monitoring available
Files Modified
v9_advanced_worker.py- Changed toint(cpu_count() * 0.7)v9_advanced_coordinator.py- No code changes, deployment uses-uflag- Deployment commands now use
python3 -ufor unbuffered output
Monitoring
Real-time logs:
tail -f /home/icke/traderv4/cluster/coordinator_70pct_unbuffered.log
Status updates: Coordinator logs every 60 seconds showing:
- Iteration number and timestamp
- Completed/running/pending counts
- Chunk launch operations
Completion
When all 1,693 chunks complete (~16 hours):
- Verify:
completed|1693in database - Count results:
ls -1 distributed_results/*.csv | wc -l(should be 1693) - Archive:
tar -czf v9_advanced_results_$(date +%Y%m%d).tar.gz distributed_results/ - Stop coordinator:
pkill -f v9_advanced_coordinator