Batch Processing Strategy & API Selection

Core

Design efficient batch processing strategies · Difficulty 3/5

batchcostapilatency

The Message Batches API allows sending multiple requests as a batch for asynchronous processing at a 50% cost discount, but requires careful workflow matching.

Key Characteristics

50% cost savings compared to synchronous API calls

Up to 24 hours processing time (no guaranteed latency SLA)

Asynchronous: fire-and-forget model with polling for results

**custom_id** field for correlating requests with responses

No multi-turn tool calling: Cannot execute tools mid-request and return results

Workflow Matching

Workflow	API	Rationale

|----------|-----|----------|

Pre-merge checks	Synchronous	Blocking, needs immediate results
Nightly test generation	Batch	Tolerates 24h latency, saves 50%
Weekly security audits	Batch	Scheduled, non-blocking
Overnight reports	Batch	Latency-tolerant background processing

SLA Calculation

When batch results feed into a workflow with SLA requirements, calculate submission frequency accounting for the 24-hour processing window. For example, to guarantee a 30-hour SLA, submit batches in 4-hour windows (30 - 24 = 6 hours buffer, submit every 4 hours for safety).

Anti-Pattern: Premature Optimization

Don't switch everything to batch for cost savings. The cost of delayed pre-merge reviews (blocked developers) exceeds the 50% batch savings.

Key Takeaways

✓Batch API saves 50% but has up to 24-hour processing with no latency SLA
✓Cannot support multi-turn tool-calling workflows due to async nature
✓Match workflow latency requirements to the appropriate API -- not everything should be batched
✓Use custom_id to correlate requests with responses and handle partial failures

Glossary Terms

Message Batches API

An asynchronous Claude API for processing multiple requests in a batch with 50% cost savings versus synchronous requests. Processing takes up to 24 hours with no guaranteed latency SLA. Does not support iterative tool use, streaming, or prompt caching. Best for scheduled, non-blocking analysis.

custom_id

A field in the Message Batches API request body that lets you correlate each batch request with its response. Must be unique within a batch. Essential for matching asynchronous results back to originating requests when processing thousands of items.

Related Concepts

Batch Cost Optimization Strategies

50% batch savings are reduced by resubmission costs -- maximize first-pass success

Batch Failure Handling & Constraints

Resubmit only failed documents identified by custom_id, not the entire batch

Test Yourself1 of 3

The code review component works iteratively: Claude analyzes a changed file, then may request related files (imports, base classes, tests) via tool calling to understand context before providing final feedback. You're evaluating batch processing to reduce API costs. What is the primary technical constraint when considering batch processing for this workflow?