Create benchmarks to measure overhead of this against `println!`

[killercup]

This crate does some stuff on top of just writing to some output. We should write some benchmarks to figure out the performance cost of that.

• Write bechmark to measure time to print n lines of example text (output.print("lorem ipsum") vs println!("lorem ipsum"))
  • to stdout using the "human" target
  • to stdout using the "human" target's test helper
  • to a file using the "json target
  • print to stdout using println!
  • print to stdout using writeln! on a locked stdout
  • print to stdout using writeln! on a buffered stdout

[flappyBug]

I'm trying to handle this issue but have encountered some problems.

1. How to target to stdout with "human" target's test helper?
2. println!'s output will captured by bencher and can't pass --nocapture like in cargo test command so it's not a fair comparison.

[killercup]

Hey! Sorry it took me a while to get around to answering this. You're asking some good (and tough!) questions, let me try to answer them and describe what I'd do :)

To make this as realistic as possible, I'd try to benchmark not functions running the code described above, but execute compiled programs. This will of course include the overhead of executing a process, but since it's a mostly constant overhead, we can measure it and, assuming our benchmark programs run long enough, we will still get valuable data. Additionally, we can easily capture the output.

So, wriring a benchmark might look like this:

• create a temp dir
• add a cargo.toml file with the required dependencies, and package name "bench"
• add a main.rs file with the code to benchmark
• run cargo build --release
• then, in each bench iteration run a subcommand like your/temp/dir/target/release/bench and wait for it to finish (but don't capture the output)
  • to test colored output, you might need to set some environment variables (see termcolor crate)

Hope this helps! I've just written this on my way to office, so I probably forgot some things. Please comment here if you have any questions!