Each limitations partial held its whole text on one line (map-and-set.mdx
was a single 1,080-character line), so any two edits to the same partial
conflicted. The partials now put one sentence per line, with a bullet's
continuation lines indented two spaces. Markdown joins the lines, so the
rendered pages are unchanged.
scripts/limitations-partials.mjs reads a labeled bullet's indented
continuation lines as part of the bullet when it splits and joins the page,
and AGENTS.md states the convention.
markAsUncloneable(value) marks a plain object, a record, an error or a
class instance (scr_json.c); structuredClone and postMessage then throw
DataCloneError "Cannot clone object of unsupported type." for it, also
where it is nested. As in Node, the mark has no effect on primitives,
arrays, typed arrays and ArrayBuffers. Marked values are retained until
the thread exits; with nothing marked, the clone paths add one branch.
worker[Symbol.asyncDispose]() terminates the worker and resolves with
undefined after its 'exit' event, so `await using` disposes a Worker at
the end of its block. The Worker handle's symbol_get op answers the
well-known symbol: the symbol unit registers Symbol.asyncDispose with the
dyn core when the program names it, and scr_dyn_is_async_dispose_symbol
tells the worker unit, so worker programs that never name the symbol do
not link the symbol unit.
static-support.json adds rows for markAsUncloneable, isInternalThread
(already lowered as false and declared) and worker[Symbol.asyncDispose]().
Corpus 5990-5991 match Node v24.22.0; corpus-costs.json records their
costs.
new MessageChannel() from node:worker_threads makes two entangled
MessagePorts. They share the handle model of parentPort: postMessage
with the existing message clone, 'message' and 'close' events,
on/once, start, close, ref, unref and hasRef. A port's 'close' reaches
the other port after its queued messages. receiveMessageOnPort(port)
answers the next queued message as { message }, or undefined.
A channel is a thread-neutral record (scr_mailbox.c): each end has its
queue and the inbox of the thread that owns its port. A port listed in a
transfer list, given as postMessage's array or { transfer }, or as the
Worker constructor's transferList, travels with the message, and the
decoding thread adopts it. The sending port becomes unusable. A port in a
message without that listing throws DataCloneError, and so does a port
listing itself.
Port events follow Node's loop phases. Each port's queued messages
arrive as one batch, ports in creation order, before setImmediate
callbacks, with nextTicks and microtasks after each message (a new loop
hook keeps the pass going until the batch is delivered). A port's own
'close' runs in the following close phase, the latest close() first. The
other port's 'close' arrives on a later poll, in the order the notices
were sent, and only while the loop keeps running.
Atomics operations on 8-, 16- and 32-bit integer arrays are sequentially
consistent atomic instructions on the element, and no longer take the
process-wide shared-memory lock. Other reads and writes of shared storage
are relaxed atomic accesses: element reads and writes access the element,
and copies, fills, conversions, searches and sorts read shared bytes into
a private copy and write back only the range they change, so concurrent
accesses to the same bytes are free of data races. Non-shared storage
keeps its plain memory accesses. Atomics.wait and Atomics.notify queue
waiters in buckets chosen by location, each with its own lock and
condition variable, so waiting threads no longer serialize other Atomics.
Atomics.store answers +0 for a value that truncates to -0, as Node does.
The shared storage runtime test also runs under ThreadSanitizer.
docs/content/docs/limitations.mdx now holds the frontmatter, the
headings, the anchor spans and one <include> line per partial. The text
moves unchanged to docs/content/limitations/: one file per labeled
bullet (<section>/<label>.mdx) and one per section's other text
(<section>.mdx). Edits to different bullets no longer touch adjacent
lines of one file.
remarkDocsConventions splices the included partials into the page and
joins the lists that consecutive bullet partials contribute, so the page,
its Markdown twin and the search index render as before. The route tests
read the page with its partials inlined. A page that includes partials
takes its last-modified date, used by the sitemap, from the newest commit
to the page or any of its partials.
docs/scripts/limitations-partials.mjs joins the partials back into one
file, splits a single-file page, and merges a branch's edits to the
single-file page into the partials.
Chris Tate