8282c38fe0
Fixes #26179. The original error reported in that issue is fixed on canary, but in local testing on my windows machine, `next build` would just hang forever. After some digging, what happens is that at some point in next build, readFile promises (from `fs/promises` ) just never resolve, and so next hangs. It turns out the issue is saturating tokio's blocking task thread pool. We previously limited the number of blocking threads to 32, and at some point those threads are all in use and there's no thread available for the file reads. What's taking up all of those threads? The answer turns out to be `tokio::process`. On windows, child process stdio uses the blocking threadpool: https://github.com/tokio-rs/tokio/pull/4824. When you poll the child's stdio on windows, it spawns a blocking task per poll, and calls `std::io::Read::read` in the blocking context. That call can block until data is available. Putting it all together, what happens is that Next.js spawns `2 * the number of CPU cores` deno child subprocesses to do work. We implement `child_process` with `tokio::process`. When the child processes' stdio get polled, blocking tasks get spawned, and those blocking tasks might block until data is available. So if you have 16 cores (as I do), there are going to be potentially >32 blocking task threadpool threads taken just by the child processes. That leaves no room for other tasks to make progress --- To fix this, for now, increase the size of the blocking threadpool on windows. 4 * the number of CPU cores should be enough to leave room for other tasks to make progress. Longer term, this can be fixed more properly when we handroll our own subprocess code (needed for detached processes and additional pipes on windows). |
||
|---|---|---|
| .. | ||
| examples/extension | ||
| js | ||
| ops | ||
| permissions | ||
| Cargo.toml | ||
| clippy.toml | ||
| code_cache.rs | ||
| errors.rs | ||
| fmt_errors.rs | ||
| fs_util.rs | ||
| inspector_server.rs | ||
| js.rs | ||
| lib.rs | ||
| permissions.rs | ||
| README.md | ||
| shared.rs | ||
| snapshot.rs | ||
| tokio_util.rs | ||
| web_worker.rs | ||
| worker.rs | ||
| worker_bootstrap.rs | ||
deno_runtime crate
This is a slim version of the Deno CLI which removes typescript integration and various tooling (like lint and doc). Basically only JavaScript execution with Deno's operating system bindings (ops).
Stability
This crate is built using battle-tested modules that were originally in the
deno crate, however the API of this crate is subject to rapid and breaking
changes.
MainWorker
The main API of this crate is MainWorker. MainWorker is a structure
encapsulating deno_core::JsRuntime with a set of ops used to implement Deno
namespace.
When creating a MainWorker implementors must call MainWorker::bootstrap to
prepare JS runtime for use.
MainWorker is highly configurable and allows to customize many of the
runtime's properties:
- module loading implementation
- error formatting
- support for source maps
- support for V8 inspector and Chrome Devtools debugger
- HTTP client user agent, CA certificate
- random number generator seed
Worker Web API
deno_runtime comes with support for Worker Web API. The Worker API is
implemented using WebWorker structure.
When creating a new instance of MainWorker implementors must provide a
callback function that is used when creating a new instance of Worker.
All WebWorker instances are descendents of MainWorker which is responsible
for setting up communication with child worker. Each WebWorker spawns a new OS
thread that is dedicated solely to that worker.