goroutines

Resources

Resource	Notes
Goroutines & Closures	Important caveat on shadowing variable in loops included
Using uiprogress	Notes I wrote about trying threadsafe progress bar package

Using Goroutines with CLI Tools

Running cli tools via goroutines can allow speeding up slow actions like code generation. I prefer to run these type of actions with a buffered channel to allow throttling the requests to avoid my laptop from catching on fire. 🔥

Here's an example using Pterm output for reporting progress (no progress bar)¹.

Playground - Go

Invoking CLI With Buffered Channels

package main

import (
    "sync"

    "github.com/bitfield/script"
    "github.com/pterm/pterm"
)

func main() {
    pterm.DisableColor()
    concurrentLimit := 4
    type runMe struct {
        title   string
        command string
    }
    runCommands := []runMe{
        {title: "commandtitle", command: "echo 'foo'"},
    }
    var wg sync.WaitGroup
    buffChan := make(chan struct{}, concurrentLimit)
    wg.Add(len(runCommands))
    pterm.Info.Printfln("running cli [%d]", len(runCommands))
    for _, r := range runCommands {
        r := r
        go func(r runMe) {
            buffChan <- struct{}{}
            defer wg.Done()
            if _, err := script.Exec(r.command).Stdout(); err != nil {
                pterm.Error.Printfln("[%s] unable to run: %s, err: %s", r.title, r.command, err)
            } else {
                pterm.Success.Printfln("[%s]", r.title)
            }
            <-buffChan
        }(r)
    }
    wg.Wait()
}

---

1. Since things are running concurrently a single bar isn't quite accurate. There are libraries out there that report correctly with goroutines, but pterm as of 2023-03 isn't one of them yet. It's being worked on. ↩