Fix worked cost example using the wrong 5s materialization interval - #988
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Fix worked cost example using the wrong 5s materialization interval#988coipond-writer[bot] wants to merge 1 commit into
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karafka-web/lib/karafka/web/config.rb:126 sets tracking.interval default 5_000 (raw per-process reporting), but config.rb:201 sets processing.interval default 2_500 (states/metrics materialization -- "we flush the states twice as often as the data reporting"). The page's own "Message Characteristics" section already states this correctly, but the worked "Example Calculation" table used the 5s figure (535,680 states/month) instead of the correct 2.5s figure (1,071,360/month), understating every downstream States/Metrics dollar and GB figure by roughly 2x. Recomputed the full cascade with the correct 2.5s interval: - States data: 16 GB -> 32 GB (30 KB x 1,071,360) - Metrics data: 32 GB -> 64 GB (60 KB x 1,071,360) - States/Metrics networking: $5.03 -> $7.44 - States/Metrics subtotal: $5.11 -> $7.52 - Total monthly cost: $39.1 -> $51.2 - Simplified Formula upper bound: $0.40 -> $0.51 (directly derived from the total / 100 consumers) Fixes #44799.
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What
`Web-UI/Operational-Cost-Breakdown.md`'s worked "Example Calculation" table used a 5-second interval for states/metrics materialization (535,680 states/month), understating every downstream States/Metrics dollar and GB figure by roughly 2x.
Why it's wrong
`karafka-web/lib/karafka/web/config.rb:126` sets `tracking.interval` default `5_000` (raw per-process reporting), but `config.rb:201` sets `processing.interval` default `2_500` (states/metrics materialization -- "we flush the states twice as often as the data reporting"). The page's own "Message Characteristics" section already states this correctly (2.5s), but the worked example's math used the wrong 5s figure.
Fix
Recomputed the full cascade with the correct 2.5s interval (1,071,360 materializations/month instead of 535,680):
The Simplified Formula's upper bound is directly derived from the total / 100 consumers, so it cascades too.
Fixes #44799 (Redmine).