Skip to main content

Overview

Workers​

Workers is a lightweight Go library for executing multiple tasks concurrently, with support for either a dynamic or fixed-limit number of workers.

Basic Usage Example​

Code​

package main

import (
  "context"
  "fmt"
  "log"
  "sync"

  "github.com/ygrebnov/workers"
)

// fibonacci calculates Fibonacci numbers.
func fibonacci(n int) int {
  if n <= 1 {
    return n
  }
  return fibonacci(n-1) + fibonacci(n-2)
}

func main() {
  // Create a new controller with a dynamic number of workers.
  // Type parameter is used to specify the type of task result.
  w := workers.New[string](context.Background(), &workers.Config{StartImmediately: true})

  wg := sync.WaitGroup{}

  // Receive and print results or handle errors in a separate goroutine.
  go func() {
    for range 10 {
      select {
      case result := <-w.GetResults():
        fmt.Println(result)
      case err := <-w.GetErrors():
        fmt.Println("error executing task:", err)
      }

      wg.Done()
    }
  }()

  for i := 20; i >= 11; i-- {
    wg.Add(1)

    // Add ten tasks calculating the Fibonacci number for a given index.
    // A task is a function that takes a context and returns a string.
    err := w.AddTask(func(ctx context.Context) string {
      return fmt.Sprintf("Calculated Fibonacci for: %d, result: %d.", i, fibonacci(i))
    })
    if err != nil {
      log.Fatalf("failed to add task: %v", err)
    }
  }

  wg.Wait() // Wait for all tasks to finish.

  // Close channels.
  close(w.GetResults())
  close(w.GetErrors())
}

In this example, Fibonacci numbers are calculated concurrently for integers from 20 down to 11. The fibonacci() function implements a basic recursive algorithm.

Explanation​

  • A workers controller is created with workers.New().

    • It is configured via workers.Config to start executing tasks immediately upon being added (see Configuration for details on configuration options).
    • The generic type parameter (string) specifies the type of the task’s result.

  • Tasks are submitted through the AddTask() method, which accepts a function matching the signature func(context.Context) string. (See Tasks for more details on supported function signatures.)

  • Task results and errors are delivered via channels:

    • GetResults() returns the results channel.
    • GetErrors() returns the errors channel.
    • Results and errors are processed using a select loop.
    • After processing, both channels are explicitly closed (see Results for more details on task execution results).

Example Output​

Calculated Fibonacci for: 20, result: 6765.
Calculated Fibonacci for: 18, result: 2584.
Calculated Fibonacci for: 19, result: 4181.
Calculated Fibonacci for: 17, result: 1597.
Calculated Fibonacci for: 16, result: 987.
Calculated Fibonacci for: 15, result: 610.
Calculated Fibonacci for: 14, result: 377.
Calculated Fibonacci for: 12, result: 144.
Calculated Fibonacci for: 13, result: 233.
Calculated Fibonacci for: 11, result: 89.

Additional Resources​