Distributed System Fallacies Trap

Code that works locally will fail in production because the network is not a function call. Before writing any code that crosses a network boundary, ask: what happens when this call is slow, fails, or returns stale data?

The Eight Fallacies

Every network call violates at least one of these. Your code must not depend on any.

#	False assumption	Reality	What breaks
1	Network is reliable	Packets drop, connections reset, services crash	Unhandled errors, partial state
2	Latency is zero	Each call adds 1-500ms; tails spike 10x	Sequential chains become seconds long
3	Bandwidth is infinite	Full object graphs saturate links at scale	Large payloads slow everything
4	Network is secure	Internal traffic can be sniffed, spoofed, replayed	Data leaks between services
5	Topology is static	Services move, scale, failover, redeploy	Hardcoded addresses break
6	One administrator	Network/cloud/security teams all have control	Can't unilaterally change config
7	Transport cost is zero	Ser/deser costs CPU at scale	JSON/protobuf encoding overhead
8	Network is homogeneous	Cross-region != same-rack; WiFi != fiber	Latency varies wildly by path

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Distributed System Fallacies Trap

The Eight Fallacies