Getting Output from Deno.run Hangs If stdin is Not Closed

[ebebbington]

I have checked with all other Deno.run issues and whilst some are similar, they dont have the same issue

Description
I am creating a subprocess, and wanting to write to it and get output. Rise and repeat this X times

Code I Am Using

const p = Deno.run({
  cmd: ["/Applications/Google Chrome.app/Contents/MacOS/Google Chrome", "--headless", "--crash-dump-dir=/tmp", "--virtual-time-budget=1000", "--repl", "https://chromestatus.com"],
  stdin: "piped",
  stdout: "piped",
  stderr: "piped"
})
await Deno.writeAll(p.stdin, new TextEncoder().encode(`window.location.href`))
for await (let line of readLines(p.stdout)) { // Hangs here
  console.log(line)
}

I can stop it from hanging by doing p.stdin.close() before the for await, but then i can't write anymore

What I Want To Be Able To Do

const p = Deno.run({
  cmd: ["/Applications/Google Chrome.app/Contents/MacOS/Google Chrome", "--headless", "--crash-dump-dir=/tmp", "--virtual-time-budget=1000", "--repl", "https://chromestatus.com"],
  stdin: "piped",
  stdout: "piped",
  stderr: "piped"
})
let lines = []
await Deno.writeAll(p.stdin, new TextEncoder().encode(`window.location.href`))
for await (let line of readLines(p.stdout)) { // Hangs here
  lines.push(line)
}
await Deno.writeAll(p.stdin, new TextEncoder().encode(`window.location.href`))
for await (let line of readLines(p.stdout)) { // Hangs here
  lines.push(line)
}
console.log(lines) // [">>> { result: ... }", ">>>", "", ">>> { result: ... }", ">>>", ""]
await p.output()
await p.stderrOutputt()
await p.stdin.close()
await p.close()

[ebebbington]

Same result with the following example:

$ cat ask.sh
read -p "name" input
echo $input

$ cat a.ts
const p = Deno.run({
  cmd: ["bash", "ask.sh"],
  stdin: "piped",
  stdout: "piped",
  stderr: "piped"
})
await Deno.writeAll(p.stdin, new TextEncoder().encode(`window.location.href`))
for await (let line of readLines(p.stdout)) {
  console.log(line)
}

It hangs, but if you add p.stdin.close() before the for await line, it works

[ebebbington]

This only seems to be a problem when the sub process is directly asking for input

[ebebbington]

Tried it in Rust too (hoping to use Rust for this instead due to this issue) but i came across the same problem, though unsure if this is due to my inexperience with Rust (very very new to it)

[wouterdebruijn]

Any updates on this? If there is a workaround available, can it be noted here? I'm running into the same issue.

[Cre3per]

Translated to Deno.Command and writing a line feed to stdin, working fine

const p = (new Deno.Command("bash", {
  args: ["./cli/tests/testdata/ask.sh"],
  stdin: "piped",
  stdout: "piped",
})).spawn();

const writer = p.stdin.getWriter();
await writer.write(new TextEncoder().encode(`window.location.href\n`));

const reader = p.stdout.getReader();
console.log(
  " read",
  `"${new TextDecoder().decode((await reader.read()).value)}"`,
);

# ask.sh
read -p "name" input
echo $input

[bartlomieju]

Deno.run() is now deprecated and Deno.Command is the recommended way of spawning subprocesses. I'm gonna close this issue.