distributed systems
18 minDistributed Systems Advanced: Rebalancing, Sagas, Consensus, and Trace Context
Design around Kafka group churn, payment idempotency, coordination limits, sagas, CQRS, and context propagation across async boundaries.
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distributed systems
9 minDistributed Systems Foundations: Consistency, Retries, and Delivery Semantics
Separate consistency guarantees from delivery guarantees and design for the partial failures that make retries necessary.
distributed systems
15 minConsensus and Observability Advanced: Quorums, Split Brain, and Trace Context
Reason about leader election across partitions and preserve causal context across Kafka, thread pools, and service boundaries.
Q&A
Q&AWhat does vector-clock incomparability represent?
Concurrent histories under the vector clock identity and propagation model.
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If neither vector is component-wise less than the other, neither history contains all represented knowledge of the other. This does not establish physical-time order or choose a globally agreed winner.
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Q&AWhere must a fencing token be enforced?
At the destination, atomically with the protected effect.
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The destination rejects generations older than its highest accepted token. A lease does not stop a paused worker, and a fence cannot reject an expired generation it has not yet learned is superseded.
distributed systems
8 minCausal order: what a logical clock can and cannot tell you
Distinguish event causality from wall-clock order with Lamport and vector clocks.
distributed systems
6 minFencing tokens: reject workers whose lease has expired
Protect a shared resource from stale owners instead of assuming expired leases stop processes.
distributed systems
5 minEvent-Time Windows: Watermarks, Late Data, and Correctable Results
Design a minute-level dashboard that tolerates delayed events without treating a watermark as proof that every event arrived.