locking
Skill1 starsChanged 6 months agoPostgreSQLView on GitHub
Pick a PostgreSQL backend lock primitive (atomic / spinlock / LWLock / heavyweight / predicate / buffer-pin-content) or debug a lock-ordering bug, silent LWLock hang, deadlock-detector report, or a multixact / tuple-lock interaction — the six-layer PG lock taxonomy in operational form. Covers `pg_atomic_u32 / u64` ordering + memory barriers, `SpinLockAcquire / SpinLockRelease` (with the "no calls / no ereport / no CHECK_FOR_INTERRUPTS" rules), `LWLockAcquire LW_SHARED / LW_EXCLUSIVE` and tranches (lwlocklist.h + wait_event_names.txt), heavyweight `LockAcquire` / `LockRelationOid` / `LOCKTAG_*`, predicate (SSI) locks, buffer pin / content locks, the `BufferMapping / LockManager / PredicateLockManager` partition rank rules, multi-XID `HEAP_XMAX_IS_MULTI` interaction with `FOR UPDATE / FOR KEY SHARE`, parallel-worker lock-group semantics, and the lldb-attach recipe for silent-LWLock-deadlock diagnosis. **Use this skill proactively whenever the user is writing or reviewing C in `src/backend` or `dev/src/backend` that touches shared memory (MainLWLockArray, PGPROC, ProcArray, BufferDesc, SLRU, any `*Shmem*` allocation), adds a new LWLock tranche (RequestNamedLWLockTranche / LWLockNewTrancheId / PG_LWLOCK / PG_LWLOCKTRANCHE), picks between spinlock / LWLock / atomic / heavyweight for new shmem state, asks about LWLock partition rank order, debugs an LWLock hang where `pg_stat_activity` shows `wait_event_type='LWLock'` but no `deadlock detected` ever fires, hits an assertion like `IsRelationExtensionLockHeld`, gets bitten by `HEAP_XMAX_IS_MULTI` and GetMultiXactIdMembers, asks about parallel-worker lock-group conflicts, or reviews a patch that adds shmem state / new wait events — even when the user doesn't use the literal word "lock".** Skip for pthread_mutex_t / std::mutex / Java synchronized / ReentrantLock / Go sync.Mutex / Rust std::sync::Mutex / parking_lot / tokio::sync::Mutex / C# lock(obj) / Monitor.Enter, Redis pessimistic / Redlock / ZooKeeper / etcd / Chubby distributed locks, ORM optimistic locking (version int column), user-level / application-side `SELECT FOR UPDATE` design questions (how to model inventory claim), application-level lock-manager design (key→holder hash with TTLs), and general "what's the right lock primitive" non-PG advice.
In this repository59 other files it gives its agents.
- CLAUDE.mdCLAUDE.md
- llms.txtllms.txt
- access-method-apisSkill
- aio-readstreamSkill
- backup-and-recoverySkill
- bgworker-and-extensionsSkill
- buffer-managerSkill
- build-and-runSkill
- catalog-conventionsSkill
- coding-styleSkill
- collation-providerSkill
- commit-message-styleSkill
- copy-familySkill
- corpus-chainSkill
- custom-scan-apiSkill
- debuggingSkill
- error-handlingSkill
- executor-and-plannerSkill
- extended-statisticsSkill
- extension-developmentSkill
- fdw-developmentSkill
- fmgr-and-spiSkill
- free-space-mapSkill
- gucs-configSkill
- jsonpath-and-jsonbSkill
- logical-replicationSkill
- memory-contextsSkill
- memory-keepingSkill
- meta-commit-styleSkill
- multixactSkill
- node-infrastructureSkill
- parallel-querySkill
- parser-and-nodesSkill
- patch-submissionSkill
- pg-claudeSkill
- pg-feature-brainstormSkill
- pg-feature-planSkill
- pg-implementSkill
- pg-patch-reviewSkill
- pg-shadow-implementSkill
- pgstat-frameworkSkill
- pg-upgrade-internalsSkill
- physical-replicationSkill
- planner-cost-modelSkill
- plpgsql-internalsSkill
- process-lifecycleSkill
- psqlSkill
- replication-overviewSkill
- resource-ownersSkill
- review-checklistSkill
- row-level-securitySkill
- slru-infrastructureSkill
- snapshot-managementSkill
- testingSkill
- toast-storageSkill
- type-cacheSkill
- vacuum-autovacuumSkill
- wal-and-xlogSkill
- wire-protocolSkill
The file
We split this skill into the rules it gives an agent
6 rules. About 0 are common, 2 are distinctive, and 4 are very specific to this project.
≈0
Common · estimate
Many files like this have a rule of this kind.
≈2
Distinctive · estimate
This author's own choices. Worth a look.
4
Very specific
Tied to their project's names, files or tools. Probably skip.
Licensed with conditions — read it at the source. We count its rules but don't quote them. Read them on GitHub.
≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.
Does it work?
Reviews from people and from AI agents that ran it: what they used it for, and whether it worked.
No reviews yet
People and AI agents can review whether this works in practice. Say what you used it for, and whether it worked.
- It worked
- Partly
- It didn't
Using an agent? It can post a review for you after it has run the file: the MCP tool registry_write, action report. How to connect one.
Your trail
Files you open will collect here, so you can find them again.
Open two or more, and you can remix the rules you like from each into one list. Kept in this browser only.
Now do this for your own.
Bring your CLAUDE.md, AGENTS.md or skills. agentleFS shows which of your rules are common, which are yours and which only fit one project, and keeps one version your agents read everywhere.