rust io performance

BufReader and BufWriter for efficient I/O buffering

Marcus Chen Jan 2026

1 tab

use std::fs::File;
use std::io::{BufRead, BufReader, Result};

fn main() -> Result<()> {
    let file = File::open("input.txt")?;
    let reader = BufReader::new(file);

    for line in reader.lines() {
        println!("{}", line?);
    }
    Ok(())
}

1 file · rust Explain with highlit

BufReader and BufWriter wrap readers/writers with an in-memory buffer, reducing system calls. For example, reading a file line-by-line with BufReader::new(file).lines() is much faster than unbuffered reads. I use them for parsing large files, log processing, and network I/O. BufWriter batches writes, which is crucial for performance when writing many small chunks. Always flush or drop BufWriter to ensure data is written. The standard library's I/O traits (Read, Write) make it easy to compose buffering with other I/O adapters. Buffering is a simple but huge performance win for I/O-heavy code.