Thread Safe Design

The logger is designed for concurrent use and can be safely shared across goroutines.

After initialization, the global slog logger can be used from HTTP handlers, background workers, scheduled jobs, and other concurrent parts of the application without additional synchronization.

Example usage:

package main

import (
	"log/slog"
	"sync"

	"github.com/netlifeguru/logger"
)

func main() {
	closer, err := logger.Init(logger.Config{
		TerminalOutput: true,
	})

	if err != nil {
		slog.Error(err.Error())
	}

	defer closer.Close()

	var wg sync.WaitGroup

	for i := 0; i < 5; i++ {
		wg.Add(1)

		go func(workerID int) {
			defer wg.Done()

			slog.Info("worker completed",
				slog.Int("worker_id", workerID),
			)
		}(i)
	}

	wg.Wait()
}

Example terminal output:

2026-05-11 12:54:39 [INFO] worker completed worker_id=0
2026-05-11 12:54:39 [INFO] worker completed worker_id=4
2026-05-11 12:54:39 [INFO] worker completed worker_id=2
2026-05-11 12:54:39 [INFO] worker completed worker_id=1
2026-05-11 12:54:39 [INFO] worker completed worker_id=3

Example file output:

{
  "time": "2026-05-11T12:54:39.74895+02:00",
  "level": "INFO",
  "msg": "worker completed",
  "worker_id": 0
}
{
  "time": "2026-05-11T12:54:39.748946+02:00",
  "level": "INFO",
  "msg": "worker completed",
  "worker_id": 4
}
{
  "time": "2026-05-11T12:54:39.748947+02:00",
  "level": "INFO",
  "msg": "worker completed",
  "worker_id": 2
}
{
  "time": "2026-05-11T12:54:39.749042+02:00",
  "level": "INFO",
  "msg": "worker completed",
  "worker_id": 1
}
{
  "time": "2026-05-11T12:54:39.748997+02:00",
  "level": "INFO",
  "msg": "worker completed",
  "worker_id": 3
}

Thread-safe logging is important for:

HTTP servers
background workers
concurrent jobs
message consumers
high-load applications

The logger handles concurrent writes internally, so application code does not need to wrap logging calls with mutexes.