Detailed explanation of the practice of asynchronous programming in Java

AsynchronousProgramming provides a non-blocking, eventdriven programming model. The following is an introduction to Java asynchronous programming practice through this article. Friends who are interested should take a look together

What is asynchronous? Why use it?

Asynchronous programming provides a non-blocking, event-driven programming model. This programming model utilizes multiple cores in the system to perform tasks to provide parallelism and therefore application throughput. The throughput rate here refers to the number of tasks performed per unit time. In this programming style, a unit of work will execute independently of the main application thread and notify the calling thread of its status: successful, processing, or failed.

We need asynchronous to eliminate the blocking model. In fact, the asynchronous programming model can use the same thread to handle multiple requests, and these requests will not block this thread. Imagine an application is using a thread to perform a task, and then waits for the task to complete before moving on to the next step. The logging framework is a good example: typically you want to log exceptions and errors to a target, such as a file, database, or other similar place. You don't want your program to wait for the log to be written before executing, otherwise the response of the program will be affected. In contrast, if the call to the log framework is made asynchronously, the application can perform other tasks concurrently without waiting. This is an example of non-blocking execution.

In order to implement asynchronous in Java, you need to use Future and FutureTask, which are located under the java.util.concurrent package. Future is an interface and FutureTask is an implementation class of it. In fact, if you use Future in your code, your asynchronous task will be executed immediately, and the calling thread can get the resulting promise.

The following code snippet defines an interface with two methods. One is a synchronous method and the other is an asynchronous method.

 import java.util.concurrent.Future;
public interface IDataManager {
  // synchronous method
  public String getDataSynchronously();
  // asynchronous method
  public Future<String> getDataAsynchronously();
}

It is worth noting that the disadvantage of the callback model is that it is very troublesome when callbacks are nested.

Do’s and Don’ts

To facilitate testing, you should isolate functionality from multiple threads in your code. When writing asynchronous code in Java, you should follow the asynchronous model so that the calling thread does not get blocked.

NoteConstructor cannot be asynchronous, you should not call asynchronous methods in the constructor. The asynchronous approach is especially useful when tasks do not depend on each other. Async should not be used when the calling task depends on the called task (Translator's note: This is meaningless for async, because the calling thread is blocked in business).

You should handle exceptions in asynchronous methods. You should not implement exceptions for long-running tasks. A long-running task, if executed asynchronously, may take longer than if executed synchronously, because the runtime must perform thread context switching for asynchronously executed methods. Storage of state, etc. You should also note that synchronous exceptions are different from asynchronous exceptions. Synchronous exceptions imply that an exception will be thrown every time the program executes to a special state of the program; tracking asynchronous exceptions is much more difficult. So synchronous and asynchronous exceptions imply synchronous or asynchronous code in your program that might raise exceptions.

Summary

Asynchronous is crucial for designing large-scale and fast-response applications. The asynchronous callback model brings many benefits; you can rely on your asynchronous callback methods to perform expensive I/O operations while your processor can perform other tasks. However, although asynchronous support is provided in Java and C

#, asynchronous programming is not always easy to implement. Use asynchronous methods with caution: you should know when to use them and when not to use them.

In this article we introduce the concept of asynchronous programming and how to implement it using Java programming. This article also lists the best practices for using asynchronous programming. thanks for reading.

Java 7 provides the

For

k/Join framework, which can divide a large task into many small tasks that can be executed in parallel. In Java 8, par

allelStream internally uses Fork/Join to perform concurrent operations. Node.js naturally supports asynchronous programming mode, and other languages ​​such as golang use goroutines and channels. It is also easy to implement asynchronous programming.

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