Bar dupes when adding new bar

So, for some reason my bar is duplicating. It always happens during the same situation. My assumption is that it is a race condition. But adding locks around all calls that touch the bar didn't help.

So, am I fundamentally missunderstanding something or could it be a bug?

I can try to make a minimally reproducable example and test in on different terminals and distros if you want.

This case happened on Windows 11, Powershell Core, Wezterm.

https://github.com/vbauerster/mpb/assets/19377618/467d1369-cbdb-4c2e-bb6f-9aac252b92d0

    progressBars := mpb.New()
LOOP:
    for {
        select {
        case response, open := <-responses:
            if !open && response == nil && extract != nil {
                // Close extract and let it finish tasks, as its buffered.
                close(extract)
                extract = nil
                continue LOOP
            }

            bar := progressBars.AddBar(100,
                mpb.PrependDecorators(
                    decor.Name(
                        "Downloading: "+filepath.Base(response.Request.URL().String()),
                        decor.WC{C: decor.DindentRight | decor.DextraSpace},
                    ),
                    decor.OnComplete(decor.AverageETA(decor.ET_STYLE_GO), "done"),
                ),
                mpb.AppendDecorators(decor.Percentage()),
            )
            go func() {
                ticker := time.NewTicker(200 * time.Millisecond)
                defer ticker.Stop()
                for {
                    select {
                    case <-ticker.C:
                        bar.SetCurrent(int64(response.Progress() * 100))
                    case <-response.Done:

                        if err := response.Err(); err != nil {
                            bar.Abort(true)
                            errChan <- fmt.Errorf("error during download: %w", err)
                        } else {
                            bar.SetCurrent(100)
                        }

                        extract <- response.Request.Context().Value("item").(Downloadable)
                        return
                    }
                }
            }()
        case err := <-errChan:
            return err
        case downloadedFile, open := <-extract:
            if !open {
                break LOOP
            }

            bar := progressBars.AddBar(100,
                mpb.PrependDecorators(
                    decor.Name(
                        "Extracting: "+filepath.Base(downloadedFile.URL),
                        decor.WC{C: decor.DindentRight | decor.DextraSpace},
                    ),
                    decor.OnComplete(decor.AverageETA(decor.ET_STYLE_GO), "done"),
                ),
                mpb.AppendDecorators(decor.Percentage()),
            )
            for i := 0; i < 10; i++ {
                time.Sleep(200 * time.Millisecond)
                bar.IncrBy(10)
            }

            if err := scoop.extract(app, resolvedApp, cacheDir, versionDir, downloadedFile, arch); err != nil {
                return fmt.Errorf("error extracting file: %w", err)
            }
        }
    }

    progressBars.Shutdown()

vbauerster / mpb

Bar dupes when adding new bar #139