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PROBLEM: Consumer throughput only 36.80 msgs/sec vs producer 50.21 msgs/sec. Test shows messages consumed at 73% of production rate. ROOT CAUSE: FetchMultipleBatches was hardcoded to fetch only: - 10 records per batch (5.1 KB per batch with 512-byte messages) - 10 batches max per fetch (~51 KB total per fetch) But clients request 10 MB per fetch! - Utilization: 0.5% of requested capacity - Massive inefficiency causing slow consumer throughput Analysis: - Client requests: 10 MB per fetch (FetchSize: 10e6) - Server returns: ~51 KB per fetch (200x less!) - Batches: 10 records each (way too small) - Result: Consumer falls behind producer by 26% FIX: Calculate optimal batch size based on maxBytes: - recordsPerBatch = (maxBytes - overhead) / estimatedMsgSize - Start with 9.8MB / 1024 bytes = ~9,600 records per fetch - Min 100 records, max 10,000 records per batch - Scale max batches based on available space - Adaptive sizing for remaining bytes EXPECTED IMPACT: - Consumer throughput: 36.80 → ~48+ msgs/sec (match producer) - Fetch efficiency: 0.5% → ~98% of maxBytes - Message loss: 45% → near 0% This is critical for matching Kafka semantics where clients specify fetch sizes and the broker should honor them.