stdout.write performance improvements

[ahaoboy]

Here is a simple example to fill the terminal and move a space:

When running with tjs, the terminal will flicker, but nodejs will run smoothly. It is not clear whether it is a platform problem of Windows, or the implementation of console.clear is different from deno/node.

let width = 0
let height = 0
if (typeof tjs !== 'undefined') {
  width = tjs.stdout.width
  height = tjs.stdout.height
} else {
  width = process.stdout.columns
  height = process.stdout.rows
}
let log;
if (typeof tjs !== 'undefined') {
  const encoder = new TextEncoder()
  log = s => tjs.stdout.write(encoder.encode(s))
} else {
  log = s => process.stdout.write(s)
}
let c = 0
const size = width * height

const sleep = n => new Promise(r => setTimeout(r, n));

(async function () {
  while (c < size) {
    console.clear()
    const s = new Array(size).fill('x')
    s[c] = ' '
    log(s.join(''))
    c++
    await sleep(16)
  }
})()

deno/console/clear

class CSI {
  static kClear = "\x1b[1;1H";
  static kClearScreenDown = "\x1b[0J";
}

clear = () => {
  this.indentLevel = 0;
  this.#printFunc(CSI.kClear, 1);
  this.#printFunc(CSI.kClearScreenDown, 1);
};

I tried running snake game with txiki, and it had no functional issues except for the terminal flickering.
https://github.com/ahaoboy/r-tui-txiki/blob/main/src/snake.tsx

[saghul]

On txiki you want to await the write call, can you try that?

[ahaoboy]

On txiki you want to await the write call, can you try that?

There is a 16ms interval between each output, perhaps due to the terminal support issue? So adding await does not seem to improve it

[saghul]

Interesting. I'll take a look!

[ahaoboy]

The problem can be improved by reducing the terminal size to some extent, I encountered a similar problem in rqjs, and realized it by refreshing the terminal every time, because it displayed a very large string without line breaks, and I'm not sure about txiki's logic yet.

pub fn print(s: String) {
print!("{s}");
let mut stdout = std::io::stdout();
stdout.flush().unwrap();
}

Interesting. I'll take a look!

This issue should not be a high priority, different platforms and terminal tools may also have an impact

[saghul]

Can you give #618 a try? It's not on par with Node, but I believe it has improved things quite a bit! The use of a different way to clear the screen was spot on!

[ahaoboy]

Can you give #618 a try? It's not on par with Node, but I believe it has improved things quite a bit! The use of a different way to clear the screen was spot on!

D:/a/txiki.js/txiki.js/src/vm.c:222:tjs__promise_rejection_tracker: Assertion `(JS_IsException(event)) == (0)' failed.

[saghul]

Oh so weird! I am not getting that on macOS! Looks like an unhandled rejection happened and creating the internal PromiseRejectionEvent failed, weird!

Do you have a full tracback by any chance?

[ahaoboy]

Do you have a full tracback by any chance?

Does tjs have an option to generate tracelog? There is no such problem on Ubuntu, and the tjs.exe also does not work on Windows.

[ahaoboy]

@saghul

This code throw Error on windows

      // Do blocking writes for TTYs:
      // https://github.com/nodejs/node/blob/014dad5953a632f44e668f9527f546c6e1bb8b86/lib/tty.js#L112
      if (!isStdin) {
        handle.setBlocking(true);
      }

[saghul]

Thanks, that helps! I force-pushed with a fix. Blocking writes are only a thing on Windows when using pipes, so added an extra check.

Can you test again please?

[ahaoboy]

Can you test again please?

Now it works!

[saghul]

Does it perform better?

[ahaoboy]

Does it perform better?

Unfortunately there doesn't seem to be

[saghul]

On macOS I can tell the difference, since resetting the terminal is more expensive than clearing it, so still worth doing.

I'll keep this open and continue digging as time allows!

[guest271314]

Depending on what code is use tjs can be faster or slower than node.

My tests don't involve a TTY.

Here's my results re "performance" of tjs, qjs, node, deno, bun, SpiderMonkey's js, and V8's d8 (using GNU Coreutils' head to read standard input to d8), fastest to slowest, reading and writing 1 MB (1048576) bytes of JSON

0 'nm_qjs' 0.10419999998807906
1 'nm_bun' 0.12319999998807907
2 'nm_deno' 0.156
3 'nm_tjs' 0.1829000000357628
4 'nm_nodejs' 0.2165
5 'nm_spidermonkey' 0.3570999999642372
6 'nm_d8' 0.4243000000119209