Web Repository - Performance & Reliability Audit¶

Executive Summary¶

This audit assesses performance bottlenecks, reliability issues, error handling coverage, and crash prevention strategies in the Psyter Web Application.

Audit Date: November 2025
Severity: 🔴 Critical | 🟠 High | 🟡 Medium | 🟢 Low

Performance Analysis¶

1. N+1 Query Pattern (🟠 High)¶

Issue: Potential multiple API calls in loops

Recommendations (Do Now):
- Batch API requests
- Implement caching strategy
- Use async parallel requests where safe

2. Session State Performance (🟠 High)¶

Issues:
- In-memory session state (non-scalable)
- Large objects in session
- Session data not distributed

Recommendations (Do Next):
- Implement distributed cache (Redis)
- Reduce session payload
- Use claims-based auth

3. API Response Caching (🟡 Medium)¶

Missing:
- Catalog data caching
- User profile caching
- Static content caching

Recommendations (Do Next):

[OutputCache(Duration = 3600, VaryByParam = "none")]
public async Task<ActionResult> GetSpecialties()
{
    // Cache appropriately
}

4. Bundle Optimization (🟢 Low)¶

Current: Basic bundling configured

Improvements:
- Enable minification in production
- CDN for static assets
- Image optimization
- Lazy loading for non-critical resources

5. Database Queries (🟢 Low - API Layer)¶

Responsibility: Backend API handles queries

Recommendations:
- Audit API performance separately
- Monitor API response times
- Implement timeout handling

Reliability Issues¶

1. Error Handling Coverage (🔴 Critical)¶

Issues:
- Inconsistent try-catch blocks
- Generic exception handling
- Poor user feedback

Current Coverage: ~40%

Recommendations (Do Now):

// Global exception handler
public class GlobalExceptionFilter : IExceptionFilter
{
    public void OnException(ExceptionContext context)
    {
        _logger.LogError(context.Exception, "Unhandled exception");

        // User-friendly error
        context.Result = new ViewResult
        {
            ViewName = "Error",
            ViewData = new ViewDataDictionary(new ErrorViewModel())
        };
        context.ExceptionHandled = true;
    }
}

2. API Failure Handling (🟠 High)¶

Issues:
- No retry logic
- No circuit breaker
- Timeout handling unclear

Recommendations (Do Now):

// Implement Polly for resilience
services.AddHttpClient<IApiDataAccess, ApiDataAccess>()
    .AddTransientHttpErrorPolicy(p => 
        p.WaitAndRetryAsync(3, retryAttempt => 
            TimeSpan.FromSeconds(Math.Pow(2, retryAttempt))))
    .AddTransientHttpErrorPolicy(p =>
        p.CircuitBreakerAsync(5, TimeSpan.FromSeconds(30)));

3. Network Failure Scenarios (🟠 High)¶

Missing:
- Offline mode handling
- Connection loss recovery
- Graceful degradation

Recommendations (Do Next):
- Implement timeout configurations
- Add retry mechanisms
- User notifications for connectivity issues

4. Session Timeout Handling (🟡 Medium)¶

Issue: Hard-coded timeout (very short)

Recommendations (Do Now):
- Extend timeout appropriately
- Implement sliding expiration
- Add session expiry warning
- Auto-save drafts

5. Video Session Reliability (🟠 High)¶

Concerns:
- WebRTC connection failures
- Network quality degradation
- Reconnection logic

Recommendations (Do Next):
- Implement connection quality monitoring
- Auto-reconnect on disconnect
- Fallback to audio-only
- Connection test before session

Crash Prevention¶

1. Null Reference Exceptions (🟠 High)¶

Common Pattern:

var userInfo = (UserLoginInfo)Session[SessionVariables.UserLoginInfo];
var email = userInfo.Email; // NullReferenceException if session expired

Recommendations (Do Now):

// Use null-conditional operators
var email = Session[SessionVariables.UserLoginInfo] 
    as UserLoginInfo)?.Email ?? "unknown";

// Or check explicitly
var userInfo = Session[SessionVariables.UserLoginInfo] as UserLoginInfo;
if (userInfo == null)
{
    return RedirectToAction("Login");
}

2. Unhandled Exceptions (🔴 Critical)¶

Issue: No global exception handler visible

Recommendations (Do Now):
- Implement global exception filter
- Log all unhandled exceptions
- Graceful error pages
- Monitor exception rates

3. Memory Leaks (🟡 Medium)¶

Potential Issues:
- Large session objects
- Event handler subscriptions
- HttpClient disposal

Recommendations (Do Next):
- Profile memory usage
- Dispose resources properly
- Use using statements
- Monitor application pool recycling

4. Deadlocks (🟡 Medium)¶

Risk Areas:
- .Result on async operations
- Synchronous calls in async methods

Recommendations (Do Now):
- Always use await
- Never use .Result or .Wait()
- Use ConfigureAwait(false) where appropriate

Monitoring & Observability¶

1. Application Insights (🟢 Low)¶

Current: Configured
Usage: Basic telemetry

Improvements:
- Custom metrics
- Performance counters
- Dependency tracking
- User analytics

2. Logging (🟠 High)¶

Current: Minimal logging

Recommendations (Do Now):

// Structured logging
_logger.LogInformation("User {UserId} booked appointment {AppointmentId}", 
    userId, appointmentId);

_logger.LogWarning("API call to {Endpoint} failed after {Attempts} attempts",
    endpoint, attempts);

_logger.LogError(exception, "Critical error processing payment {PaymentId}",
    paymentId);

3. Health Checks (🟡 Medium)¶

Missing: No health endpoints

Recommendations (Do Next):

// Add health checks
services.AddHealthChecks()
    .AddCheck("api", () => CheckApiHealth())
    .AddCheck("session", () => CheckSessionState());

app.MapHealthChecks("/health");

Load Testing Recommendations¶

Performance Benchmarks¶

Target Metrics:
- Page load: Fast
- API response: Quick
- Video session latency: Low
- Concurrent users: 1,000+

Tools:
- JMeter
- k6
- Azure Load Testing
- Application Insights

Test Scenarios:
1. User registration/login
2. Appointment booking
3. Video session initiation
4. Concurrent API calls

Priority Action Plan¶

Do Now (Immediate Priority) 🔴¶

1. Implement global exception handler
2. Add null-checking to session access
3. Fix async/await patterns
4. Implement API retry logic
5. Add structured logging
6. Extend session timeout

Do Next (High Priority) 🟠¶

1. Implement caching strategy
2. Add health checks
3. Distributed session state
4. Video session reliability
5. Memory profiling
6. Load testing

Plan (Future Improvements) 🟡¶

1. Performance optimization
2. Comprehensive monitoring
3. Disaster recovery plan
4. Scalability improvements

Conclusion¶

Overall Reliability Score: 6/10

Critical Issues:
1. Inconsistent error handling
2. No retry/circuit breaker
3. Short session timeout
4. Lack of monitoring

Priority: Improve error handling and API resilience immediately.

Document Version: 1.0
Last Updated: November 2025
Next Review: Quarterly