Thread pool and task queue in Go language

Thread pool and task queue in Go language

With the continuous development of computer technology, multi-threaded programming has become a mainstream programming method. The thread pool and task queue are two very important concepts in multi-threaded programming. In the Go language, thread pools and task queues also play a very important role.

1. Thread pool

Thread pool is a kind of pre-created certain number of threads and stored in the pool. When a task needs to be executed, an idle thread is taken out from the thread pool. to perform tasks. This method can make full use of the CPU resources in the computer and avoid performance problems caused by frequent creation and destruction of threads.

In Go language, goroutine (coroutine) is used instead of thread. Goroutine is a lightweight thread in the Go language. Multiple goroutines can be created in a single thread. Each goroutine can execute tasks in parallel with very little consumption. The use of thread pools can further optimize the use of goroutines and avoid performance problems caused by creating and destroying goroutines too frequently.

The Go language also has a built-in thread pool implementation. Generally, the number of available goroutines is set by calling the runtime.GOMAXPROCS function in the standard library. For example, you can use the following code to set the number of available goroutines for the number of CPU cores:

import "runtime"

func main() {
    num := runtime.NumCPU() // 获取CPU核心数
    runtime.GOMAXPROCS(num) // 设置可用的goroutine数量
}

You can obtain the number of currently running goroutines through the runtime.NumGoroutine function. Please note here What is important is that setting the number of available goroutines is not as high as possible. It should be adjusted according to the actual situation to achieve the optimal effect.

2. Task Queue

The task queue is a queue used to store tasks to be executed. The application puts the tasks into the queue, and the threads in the thread pool will continue to flow from the task queue. Get the task and execute it. Task queues usually use a first-in-first-out (FIFO) method to execute tasks, which ensures that newly added tasks are always queued behind existing tasks and existing tasks are executed first.

In the Go language, you can use channel to implement task queues, and goroutines can communicate through channels. For example, you can use the following code to create a channel with a buffer:

taskChan := make(chan Task, 10) // 创建带有缓冲区的任务队列

Here, a task queue that can store 10 tasks is created through the make function. When the producer goroutine needs to put a task into the task queue, it can do so through taskChan. For example, you can use the following code to put a task into the task queue:

task := Task{...} // 创建一个任务
taskChan <- task  // 将任务放入任务队列

When the consumer goroutine needs to take out the task from the task queue and execute it, it can also operate through taskChan . For example, you can use the following code to take out a task from the task queue and execute it:

task := <-taskChan // 从任务队列中取出一个任务
task.Execute()     // 执行该任务

It should be noted that using channel to implement the task queue can also prevent excessive creation of goroutines and excessive Performance issues caused by destroying goroutine.

3. Combination of thread pool and task queue

In actual applications, thread pool and task queue are usually used at the same time. The thread pool can store a certain number of goroutines and process tasks in the task queue, thereby realizing concurrent execution of tasks and increasing the number of concurrent requests that the system can handle. For example, in a web service, each HTTP request can be put into the task queue as a task, and the goroutine in the thread pool will continuously take out tasks from the task queue and process them, thereby improving the concurrent processing capabilities of HTTP requests.

In the Go language, you can wait for all goroutine execution to complete by using sync.WaitGroup. For example, you can use the following code to wait for all goroutine executions to complete:

var wg sync.WaitGroup // 定义WaitGroup对象

// 添加goroutine到WaitGroup中
for i := 0; i < num; i++ {
    wg.Add(1)
    go func() {
        // 处理任务队列中的任务
        ...
        wg.Done()
    }()
}

// 等待所有goroutine执行完成
wg.Wait()

It should be noted that when using thread pools and task queues, the overall load of the system and the number of tasks in the queue should be fully considered. Number of tasks to avoid overall performance degradation of the system due to too many or too few tasks.

In short, in the Go language, using thread pools and task queues can process tasks more effectively, improve the concurrent processing capabilities of applications, and thus bring a better user experience to applications.

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