RFC: Implement Resilient Error Handling for API Overload Conditions

[aygp-dr]

RFC: Implement Resilient Error Handling for API Overload Conditions

Background

Currently, the sampling loop is vulnerable to API overload conditions (error 529), which can result in frequent failures and noisy error reporting. This impacts both reliability and user experience.

Problem

When encountering error 529 (overloaded_error), the current implementation:

• Fails immediately without retrying
• Generates noisy error logs
• Doesn't implement any backoff strategy
• May contribute to the overload condition through immediate retries

Proposed Solution

Implement a resilient error handling strategy with:

1. Exponential Backoff

   • Start with 1 second base delay
   • Exponential increase (1s, 2s, 4s, 8s, 16s)
   • Maximum of 5 retries
   • Cap maximum delay at 5 minutes

2. Smart Retry Logic

   max_retries = 5
   base_delay = 1  # Start with 1 second delay
   
   for attempt in range(max_retries):
      try:
          raw_response = client.beta.messages.with_raw_response.create(...)
          break  # Success, exit retry loop
      except InternalServerError as e:
          if "overloaded_error" in str(e):
              if attempt == max_retries - 1:
                  return messages  # Final attempt failed
   
              delay = min(300, base_delay * (2 ** attempt))
              jitter = random.uniform(0, 0.1 * delay)  # 10% jitter
              sleep_time = delay + jitter
              time.sleep(sleep_time)
              continue

3. Improved Error Handling

   • Specific handling for overloaded vs other internal server errors
   • Better error attribute handling using getattr()
   • Cleaner error reporting structure

Benefits

1. Improved Reliability

   • Higher success rate during high load periods
   • Automatic recovery from temporary overload conditions
   • Reduced impact on the API service through smart backoff

2. Better User Experience

   • Less noisy error reporting
   • More predictable behavior
   • Transparent retry process

3. System Health

   • Reduced load on API during stress periods
   • Better alignment with best practices for API consumption
   • More maintainable error handling code

Questions for Discussion

1. Are the retry parameters (max retries, delays) appropriate?
2. Should we add logging for retry attempts?
3. Should we consider implementing circuit breaker pattern for sustained outages?
4. Do we need to handle other error codes similarly?

Implementation Details

The implementation requires:

1. Adding imports: random, time
2. Modifying the sampling loop to include retry logic
3. Updating error handling structure
4. Adding appropriate type hints and documentation

Alternatives Considered

1. Client-side rate limiting: Rejected as it doesn't handle dynamic server conditions
2. Fixed retry delay: Rejected as it doesn't scale well with varying load
3. Infinite retries: Rejected to prevent hanging in case of sustained issues

Testing Strategy

1. Unit tests for backoff calculation
2. Integration tests with mocked 529 responses
3. Load testing to verify behavior under stress

Migration Plan

This change is backward compatible and can be rolled out directly as it only affects error handling behavior.

[jwalsh]

anthropic.InternalServerError: Error code: 529 - {'type': 'error', 'error': {'type': 'overloaded_error', 'message': 'Overloaded'}}