shoney.arickathil
71d3985e81
- 9e durability/throughput/scale: the measurement backbone -- run the employee program, restart to prove persistence, benchmark read/write through compiled .wo, ~1M-row mixed load with throughput floor + p99 ceiling + flat RSS; the gate every optimization signs (before/after delta required, no measured delta = not accepted) - 9f io_uring group-commit: replace fsync-per-commit with batched io_uring durability overlapped on shard threads; same ack-after- durable contract, crash battery unchanged, automatic fsync fallback on kernels without it; deliberately LAST (needs 8's threads to overlap and 9e's baseline to beat) - wired the existing levers into the arc: iteration 8 (thread-per-core) = "optimize multithreading", 7b (mark-sweep) = "implement GC" -- each now gated by re-running 9e and recording the delta - explicit sequence recorded in 9e: 9b lands -> 9e baseline -> 7b re-bench -> 8 re-bench -> 9f re-bench - roadmap + board rows for 9e/9f; four forks each for the specs (load generator, absolute vs relative budgets, what "1M" means, durable vs RAM headline; ring model, liburing vs raw, batch boundary, fallback testing) Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
58 lines
2.4 KiB
Markdown
58 lines
2.4 KiB
Markdown
# Iteration 8 — shard-actor runtime
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> Format: `product/story-iteration-template`. Part of
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> [Story — one language, one runtime, one database, one binary](00-story.md).
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## Goals
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- The runtime scales past one core the doctrine way: pinned thread-per-core
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shards, each owning its own heap and event loop; cross-shard
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communication is a message send that **moves ownership** — shared mutable
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state never exists.
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- The language grows `spawn` and message send; garbage collection stays
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per-shard, so no global pause appears at any core count.
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## Acceptance Criteria
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- What to achieve?
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- **Given** a program spawning actors across shards,
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- **when** an owned object is sent to another shard,
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- **then** the sender can no longer touch it (compile-time move), the
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receiver owns it, and its eventual free routes back to its
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allocation-home arena.
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- What to achieve?
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- **Given** debug builds with shard-ownership asserts,
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- **when** the deterministic actor corpus runs under ASan and TSan,
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- **then** zero races, zero leaks, and identical output across runs.
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- What to achieve?
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- **Given** a `@gc` reference,
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- **when** code attempts to send it cross-shard,
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- **then** the compiler rejects it — aliased references cannot cross
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heap boundaries.
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## Out Of Scope
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- Fibers/green threads (recorded in the blue-green vision §3; extends this
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scheduler later).
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- Cross-shard transactions (the database iteration's 2PC concern, later).
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## Info
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- The C reference (`runtime/wo-rt.c`, phases A–F) is the substrate: epoll
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loops, eventfd mail, the machinery this iteration lifts into `wovm`.
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- The VM's object header has carried a shard id since iteration 2 — no
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relayout.
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- **Gated by the benchmark (2026-08-15):** this is the "optimize
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multithreading" lever of the performance arc — thread-per-core is a
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throughput/scale claim, so landing it means re-running iteration
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[9e](09e-durability-throughput-scale.md) at the connection/concurrency
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scale it unlocks and recording the before/after delta. It is also where
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the io_uring write path ([9f](09f-io-uring-commit.md)) gets a thread to
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overlap durability against.
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## Proposed Solution
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- Execute the existing plan: `docs/superpowers/plans/2026-08-01-shard-actor-vm-runtime.md`
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(pinned-worker scheduler, shard-stamped heaps, MPSC mailbox rings + mail
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eventfds, send-as-move with home-routed frees, gc pacing per tick,
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spawn/send surface, actor corpus).
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