fix(node): Rework node:child_process IPC (#24763)

Fixes https://github.com/denoland/deno/issues/24756. Fixes
https://github.com/denoland/deno/issues/24796.

This also gets vitest working when using
[`--pool=forks`](https://vitest.dev/guide/improving-performance#pool)
(which is the default as of vitest 2.0). Ref
https://github.com/denoland/deno/issues/23882.

---

This PR resolves a handful of issues with child_process IPC. In
particular:

- We didn't support sending typed array views over IPC
- Opening an IPC channel resulted in the event loop never exiting
- Sending a `null` over IPC would terminate the channel
- There was some UB in the read implementation (transmuting an `&[u8]`
to `&mut [u8]`)
- The `send` method wasn't returning anything, so there was no way to
signal backpressure (this also resulted in the benchmark
`child_process_ipc.mjs` being misleading, as it tried to respect
backpressure. That gave node much worse results at larger message sizes,
and gave us much worse results at smaller message sizes).
- We weren't setting up the `channel` property on the `process` global
(or on the `ChildProcess` object), and also didn't have a way to
ref/unref the channel
- Calling `kill` multiple times (or disconnecting the channel, then
calling kill) would throw an error
- Node couldn't spawn a deno subprocess and communicate with it over IPC

1 files changed, 2 insertions, 2 deletions

diff --git a/cli/args/mod.rs b/cli/args/mod.rs
index b288751a7..76644028c 100644
--- a/cli/args/mod.rs
+++ b/cli/args/mod.rs
@@ -1068,10 +1068,10 @@ impl CliOptions {
   }
 
   pub fn node_ipc_fd(&self) -> Option<i64> {
-    let maybe_node_channel_fd = std::env::var("DENO_CHANNEL_FD").ok();
+    let maybe_node_channel_fd = std::env::var("NODE_CHANNEL_FD").ok();
     if let Some(node_channel_fd) = maybe_node_channel_fd {
       // Remove so that child processes don't inherit this environment variable.
-      std::env::remove_var("DENO_CHANNEL_FD");
+      std::env::remove_var("NODE_CHANNEL_FD");
       node_channel_fd.parse::<i64>().ok()
     } else {
       None