Thread safety in Java API development

Java API is one of the most widely used programming languages, which can help developers quickly build cross-platform applications. However, thread safety issues are one of the very common problems during Java API development. Thread safety means that when multiple threads access a shared resource at the same time, incorrect data concurrency problems will not occur.

In Java API development, there are many ways to achieve thread safety processing. We can ensure thread safety by locking shared resources, using synchronization methods, or using the volatile keyword. The specific implementation of these methods will be introduced below.

1. Locking shared resources

Locking shared resources is the most commonly used thread-safe processing method in Java API development. It mainly uses the synchronized keyword to ensure that only one thread can be accessed at the same time. A thread accesses a shared resource. There are two specific implementation methods:

(1) Lock the entire method

The implementation method of using the synchronized keyword to modify the entire method is very simple. You only need to add the synchronized keyword before the method signature. Can. As shown below:

public synchronized void method(){
// Code blocks that need to be synchronized
}

This method can ensure thread safety well, but it The disadvantage is that the efficiency is low. When multiple threads access it at the same time, only one thread can enter the method body, and other threads need to wait, thus reducing the concurrency performance of the program.

(2) Lock shared resources

In addition to locking the entire method, we can also achieve thread safety by locking shared resources. The specific implementation is to use the synchronized keyword in the code block that needs to be synchronized to lock the shared resource. As shown below:

public void method(){
synchronized (object){

// 需要同步的代码块

}
}

This method is relatively flexible, only When multiple threads need to access shared resources at the same time, synchronization is required, thereby improving the concurrency performance of the program.

2. Use synchronization method

The synchronization method is similar to locking the entire method. You only need to add the synchronized keyword before the method signature. As shown below:

public synchronized void method(){
// Code block that needs to be synchronized
}

The main advantage of the synchronized method is that it can synchronize locks and methods Bound together, this means that the synchronization lock is automatically released, thus avoiding deadlock problems. But its disadvantages are similar to locking the entire method, which is less efficient.

3. Use the volatile keyword

Using the volatile keyword can ensure the visibility of shared variables and ensure thread safety even when interacting between multiple threads. As shown below:

public volatile int number = 0;

When a variable is marked as volatile, each modification will be forced to be flushed to the main memory, and the latest will be re-obtained the next time it is accessed. value. Due to this mechanism, volatile can ensure visibility between multiple threads and optimize program performance.

4. Use thread pool

In Java API development, using thread pool is also a very common thread safety method. The thread pool can avoid the overhead of creating threads by creating threads in advance and then assign tasks to these threads, and can control the number of threads executing concurrently, thereby reducing the waste of resources. The thread pool can be created using the ThreadPoolExecutor class provided by the JDK, as shown below:

ThreadPoolExecutor executor = new ThreadPoolExecutor(5, 10, 5000, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>(100));

Among them, the parameters respectively represent the number of core thread pools, the maximum number of thread pools, allowed thread idle time, waiting queue and rejection policy. When using a thread pool, we can control how tasks are executed through task queues and rejection policies to ensure thread safety.

Summary

Thread safety processing in Java API development is a very important issue. Different application scenarios require different thread safety processing methods. This article introduces four commonly used methods, among which locking shared resources is the most commonly used method, but it will have a greater impact on program efficiency. Therefore, in practical applications, we should choose the most appropriate thread safety processing method according to specific scenarios.

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