Zap is not logging inside some loops

[jptosso]

hello, I have an implementations that creates a few thousands of logs in a second and Zap seems to print most of them but it misses some, without a pattern, the function is:

func (p *Parser) FromString(data string) error {
	scanner := bufio.NewScanner(strings.NewReader(data))
	var linebuffer = ""
	pattern := regexp.MustCompile(`\\(\s+)?$`)
        p.Waf.Logger.Debug("do some logging here")
	for scanner.Scan() {
		p.currentLine++
		line := scanner.Text()
		linebuffer += strings.TrimSpace(line)
		// Check if line ends with \
		match := pattern.MatchString(line)
                fmt.Println(line)
		p.Waf.Logger.Debug("Parsing partial line", zap.String("line", line),
			zap.Int("line_number", p.currentLine))
		if !match {
			err := p.evaluate(linebuffer)
			if err != nil {
				return err
			}
			linebuffer = ""
		} else {
			linebuffer = strings.TrimSuffix(linebuffer, "\\")
		}
	}
	return nil
}

No log inside that loop will be generated but every other log will be displayed, also the "do some logging here" debug log will be shown and the fmt.Println(line). There are a few exceptions, somehow it does show logs from inside the loop some times.

Here is my zap init code:

func (w *Waf) SetDebugLogPath(path string) error {
	cfg := zap.NewProductionConfig()
	if path == "" {
		cfg.OutputPaths = []string{}
	} else {
		cfg.OutputPaths = []string{"/dev/stdout"}
	}
	cfg.Level = *w.loggerAtomicLevel
	logger, err := cfg.Build()
	if err != nil {
		return err
	}
	w.Logger = logger
	return nil
}

I'm using version v1.19.1

What am I doing wrong :(

[prashantv]

When the default production config is used, zap does sampling by default. You can disable sampling by setting the sampling policy to nil,

	cfg := zap.NewProductionConfig()
	cfg.Sampling = nil // disable sampling