Cloudflare halves DNS build delay and cuts memory use by 85% with targeted builds

Details

Cloudflare Zone Builder now uses a targeted build planner and unified scheduler to halve DNS build completion delay and cut peak memory usage by 85%.
Peak memory dropped from 79 GiB to 12 GiB, and average working-set memory decreased from 49 GiB to 7 GiB (86% reduction).
Median build completion delay was halved from approximately 7.7 seconds to 3.3 seconds, while the p99 maximum spike dropped from 14.6 minutes to 1.21 minutes.
92.95% of builds avoided full zone rebuilds, with 86.81% classified as resources-only builds.
Targeted builds execute only the minimum necessary work by proving safety for specific DNS name or metadata changes, falling back to full builds when safety cannot be proven.
A unified scheduler merges events for the same zone before build start, using soft committing to prevent message loss during restarts.
Rollout validation used a mirror Zone Builder environment to compare targeted and full build outputs byte-for-byte on a 20% sample of zones.

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