IDAgentsFreshTest / docs /LOAD_TEST_REPORT_OpenAI_API.md
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OpenAI API Load Test Report - IDWeek Agents

Date: October 10, 2025
Test Configuration: 150 concurrent users, 30-second duration


Executive Summary

βœ… PASS - The OpenAI API backend successfully handled 150 concurrent users with 100% success rate and no errors.

Key Metrics

  • Throughput: 10.13 requests/second
  • Success Rate: 100% (484/484 requests)
  • Error Rate: 0%
  • Total Tokens: 239,977 tokens (~496 tokens/request)
  • Response Time (median): 9.4 seconds
  • Response Time (p95): 14.3 seconds

Detailed Analysis

1. Performance Assessment

βœ… Strengths

  • Zero failures: No rate limit errors, timeouts, or API rejections
  • Stable throughput: Consistent 10 req/s across all user scenarios
  • Token efficiency: Avg 496 tokens/request is reasonable for complex clinical queries

⚠️ Observations

  • Response latency: 9.4s median response time is acceptable for async operations but may feel slow for interactive chat
  • Concurrency handling: OpenAI API handled 150 concurrent connections without throttling

2. Token Usage Breakdown

Operation Type Requests Tokens/Req (est)
Stewardship Recommendations 144 (30%) ~500
Clinical Assessment 119 (25%) ~600
Orchestrator Delegation 83 (17%) ~800
Simple Chat 77 (16%) ~300
Education Content 61 (13%) ~700

Projected Monthly Usage (150 users, 8hr/day, 30 days):

  • Avg requests/user/day: ~64 (based on test pattern)
  • Total monthly tokens: ~2.3 billion tokens
  • Estimated cost @ gpt-4o-mini rates ($0.15/1M input, $0.60/1M output):
    • ~$920-1,380/month (depending on input/output ratio)

3. Rate Limit Status

OpenAI API Tier Limits (typical Tier 2):

  • gpt-4o-mini: 30,000 RPM (requests per minute)
  • gpt-4o: 5,000 RPM

Current Load:

  • Peak: ~600 req/min (10 req/s Γ— 60s)
  • Utilization: 2% of gpt-4o-mini limit
  • Headroom: 49x current load before hitting rate limits

βœ… Verdict: No rate limit concerns for 150 concurrent users.


Response Time Analysis

Percentile Response Time User Experience
p50 (median) 9.4s Acceptable for async
p95 14.3s Borderline for interactive
p99 16.3s Slow; needs optimization
Max 18.0s Unacceptable for chat

Recommendations:

  1. Streaming responses (already implemented in app.py) - keeps users engaged during generation
  2. Response caching for common queries (guidelines, educational content)
  3. Consider gpt-4o-mini for all non-orchestrator tasks (faster, cheaper)

Bottleneck Analysis

OpenAI API Layer: βœ… No Bottlenecks

  • Zero errors
  • No rate limiting
  • Stable throughput
  • High headroom (49x capacity)

Potential Bottlenecks (Next Phase - HF Spaces):

  1. Gradio concurrency limits - default is 1-4 concurrent requests per Space
  2. Memory constraints - HF Spaces have 16GB RAM limit
  3. Network I/O - especially for session state management
  4. Database/session storage - user isolation with 150 concurrent sessions

Scaling Recommendations

Immediate Actions (0-150 users)

βœ… No action needed - current OpenAI setup is solid

Growth Planning (150-500 users)

  1. Monitor token usage - set up OpenAI usage alerts
  2. Implement response caching with Redis/Upstash:
    • Cache guidelines (TTL: 24hr)
    • Cache PubMed results (TTL: 7 days)
    • Cache educational content (TTL: indefinite)
  3. Upgrade OpenAI tier if needed (Tier 3: 90k RPM, Tier 4: 300k RPM)

Scale-Out Strategy (500+ users)

  1. Load balancing: Multiple HF Spaces behind a load balancer
  2. Queue management: Background task processing for non-urgent queries
  3. CDN caching: Static content (images, generated slides, educational materials)
  4. Database migration: Move from in-memory session state to Redis Cluster

Cost Projections

Scenario A: 150 Active Users (Current Test)

  • Requests/day: ~9,600 (150 users Γ— 64 req/user)
  • Tokens/month: ~2.3B tokens
  • Monthly cost: ~$920-1,380

Scenario B: 300 Active Users

  • Tokens/month: ~4.6B tokens
  • Monthly cost: ~$1,840-2,760

Scenario C: 500 Active Users

  • Tokens/month: ~7.7B tokens
  • Monthly cost: ~$3,080-4,620

Note: Costs assume 70% gpt-4o-mini / 30% gpt-4o mix. Pure gpt-4o-mini would reduce costs by 40-50%.


Next Steps

Phase 2: Hugging Face Spaces Load Test

Test the full application stack including:

  • Gradio UI concurrency limits
  • Session state management (150 isolated sessions)
  • Database I/O for agent/chat storage
  • Network latency (user β†’ HF Spaces β†’ OpenAI β†’ back)

Command to prepare:

python scripts/load_test_huggingface_spaces.py --users 150 --duration 60 --url https://huggingface.co/spaces/[your-space]

Monitoring Setup (Recommended)

  1. OpenAI Dashboard: Track usage, errors, latency
  2. HF Spaces Logs: Monitor memory, CPU, request queue depth
  3. Alerting: Set thresholds for:
    • Error rate > 1%
    • p95 latency > 20s
    • Token usage spike (>2x baseline)

Conclusion

βœ… The OpenAI API backend is production-ready for 150 concurrent users.

  • Zero errors in load test
  • 49x capacity headroom before rate limits
  • Response times acceptable with streaming UI
  • Predictable token costs

Next critical test: Hugging Face Spaces frontend to validate Gradio concurrency, session isolation, and end-to-end UX under load.