NKESSLING@TERMINALSCREEN WORKOpen to work from Nov 2026RTM 22:24:53 · UTC 20:24

KILN ~/work/kiln MAINTAINED

KILN★ 2,207▲ 1.29 commits/day, 40 wkGO · 2023–26

A build cache that made CI six times faster

A content-addressed build cache daemon. A hit on one branch is a hit on every branch.

ROLE: Author
STACK: Go · gRPC · content addressing
YEARS: 2023–26

COMMIT RATE · 40 WEEKS · KILN

6.1xfaster CI, median

94%cache hit rate

41 TBserved last month

README.md · CASE STUDY

A content-addressed build cache daemon. A hit on one branch is a hit on every branch.

Our CI rebuilt the same objects on every branch because cache keys included the branch name. Cold pipelines took 18 minutes and engineers stopped waiting for them.

The fix

kiln keys every build step by a hash of its real inputs: source files, environment and toolchain version. Nothing else. A step that ran on main is a hit on every feature branch that did not change its inputs.

Running it

A small hot set lives in memory in front of disk, eviction runs by total size, and large objects stream in 4 MB chunks. One daemon serves 40 engineers across two companies.

Result

Median CI time fell from 18 m 04 s to 2 m 57 s, and egress dropped by 80%. The sizing guide in the repo covers teams from 10 to 100 engineers.

SCRN WORK · SCREENER6 OF 8 SHOWN

More projects.

Every project opens the same way: problem, fix, numbers.

ROLEKEY RESULT

TIDEA write-ahead log that survives the power cordtidewaterAuthor · maintainerRust2024–264,8121.92 GB/s append, one core KILNA build cache that made CI six times fasterkilnAuthorGo2023–262,2076.1x faster CI, median LOOMA Postgres job queue that stays fair under loadloom-queueAuthor · 3 contributorsTypeScript2024–251,39012k/s jobs on one node WRENRelease notes that write themselves from commitswrenAuthorTypeScript2025–261,04511 min saved per release PRSMRead traces in the terminal and diff two runsprism-traceAuthorRust2025961O(n log n) trace diff, was O(n²)FERNA small config language with typesfernAuthorZig2025–266120.4 ms compile a 2k-line config

ALL 8 PROJECTS ↗

NOTE WRITING · RESEARCH NOTES8 NOTES

Notes from the work.

Short write-ups of things that broke and how they got fixed. Plain language, real numbers.

Storage

18 SEPT 20267 min READ

You also have to fsync the directory

Why a new file is not durable until its directory is, and the crash test that proved it.

READ NOTE <GO>

30 AUG 2026Build systemsCache keys are inputs, not branch names9 min 12 JUL 2026DatabasesFair queues in Postgres, with SKIP LOCKED11 min 02 JUN 2026StorageGroup commit, drawn by hand6 min ALL NOTES ↗