Module runtime_util 

Tokio runtime builders (budgeted multi-thread workers for CDP + HTTP fan-out). Tokio runtime builders tuned for one-shot CLI with bounded parallelism.

Workload

Mista / I/O-bound (Chrome CDP + HTTP). Async coordinates wait; CPU work uses Rayon or spawn_blocking (see crate::concurrency).

Product latency model

Wall time is dominated by Chrome CDP / network I/O, not Rust CPU. Rules rules_rust_latencia_reduzir + rules_rust_paralelismo require:

• Bounded runtimes — worker count from crate::concurrency::browser_worker_threads (not unbounded num_cpus on a one-shot agent process; hard-capped at 8).
• No blocking work on async workers without spawn_blocking.
• No PGO/BOLT/isolcpus/mlockall as product defaults (daemon/HFT ops; product law is BORN→EXECUTE→FINALIZE→DIE).

Latency budgets (agent-facing, host-local, release build)

Path	P99 budget (order of magnitude)	Notes
Clap parse + doctor offline quick	≤ 50 ms	No Chrome; meta path
--help cold	≤ 80 ms	First process image load
JSON envelope encode (small)	≤ 100 µs	Criterion / unit
Chrome launch + first CDP	seconds	External; not Rust hot path

Budgets are ceilings for regression detection, not SLOs for trading. Re-measure with scripts/latency-baseline.sh after runtime changes.

Runtime flavours

Helper	Flavour	Use
block_on_browser_timeout	multi-thread, budgeted workers	CDP event fan-out
[block_on_io]	multi-thread, budgeted (I/O pipelines)	HTTP scrape / batch / crawl

Never create an unbounded new_multi_thread() without the concurrency budget.

Constants

BROWSER_THREAD_NAME

Thread name prefix for browser runtime workers (bac-browser-0, …).

IO_THREAD_NAME

Thread name prefix for I/O multi-thread runtimes.

Functions

block_on_io

Drive an async I/O future to completion on a budgeted multi-thread runtime.

build_browser_runtime

Build the multi-thread runtime used for Chrome CDP sessions.

build_io_runtime

Build a multi-thread runtime for HTTP / offline async fan-out.