Process bottleneck detection.
Identifies GenServer modules with high synchronous call fan-in: 5 or more
distinct caller modules make GenServer.call to the same target. These are
serialization points that can become throughput bottlenecks under load.
Low fan-in GenServers (1–4 callers) are normal centralized services and are not reported.
Requires the OTP extractor for sync_call and implements_behaviour facts.
Output relations
bottleneck_caller(caller_mod, target_mod)— caller of a high-fan-in GenServer.sync_call_fan_in(target_mod, count)— number of distinct callers (>= 5 only).
Finding severities
sync_call_fan_in—:warning. The headline finding: a single process serializing five or more caller modules is a throughput ceiling waiting for load.bottleneck_caller—:info. Supporting evidence: one row per caller of the bottleneck.