The technical principles and back moves of JSR 166 in the Java class library

The JSR 166 is an important standard for the Java platform and mainly focuses on the field of concurrent programming.This standard defines a concurrent framework for simplifying multi -threaded programming, and provides various concurrent tools and data structures to support efficient and secure concurrency operations. The technical principles of JSR 166 include the following aspects: 1. Concurrent tool class: JSR 166 provides a series of concurrent tools, such as Semaphore, Countdownlatch, CyclicBarrier, etc.These tools to achieve synchronization and mutual exclusion by using the underlying AQS (ABSTRACTQUEDSYNCHRONIZER) mechanism. 2. Thread pool: JSR 166 introduced the Executor framework, providing support for the thread pool.By using a thread pool, the frequent creation and destruction of threads can be avoided, and the performance and resource utilization rate of programs can be improved. 3. Atomic variables: JSR 166 provides a set of atomic variables, such as Atomicinteger, Atomiclong, etc.These classes use hardware -level atomic operations to ensure that the reading and writing operation of variables is atoms, which avoids inconsistent data during multi -threaded concurrent operations. 4. Parallel data structure: JSR 166 introduces some concurrent data structures, such as ConcurrenThashmap, ConcurrentLinkedQueue, etc.These data structures use lock separation technology and lock -free algorithm to achieve high and compact read and write operations. 5. Fork/Join framework: JSR 166 introduces the FORK/JOIN framework to solve a specific type of parallel computing problem.This framework divides the problem into smaller sub -tasks, and then performs these sub -tasks concurrently, and the results are merged to achieve efficient parallel computing. The technical principles of JSR 166 make developers more conveniently write high -efficiency and thread -safe complication procedures.The following is a simple Java code example, demonstrating how to use the concurrent tool class provided by JSR 166: import java.util.concurrent.Semaphore; public class ConcurrentExample { public static void main(String[] args) { Semaphore semaphore = New Semaphore (3); // Create a semaphore, the initial permit is 3 for (int i = 0; i < 10; i++) { new worker (i, semaphore) .start (); // Create 10 work threads and start } } static class Worker extends Thread { private int id; private Semaphore semaphore; public Worker(int id, Semaphore semaphore) { this.id = id; this.semaphore = semaphore; } public void run() { try { semaphore.acquire (); // Get a license System.out.println ("worker" + ID + "is working"); Thread.sleep(1000); semaphore.release (); // Release a license System.out.println ("worker" + ID + "work complete"); } catch (InterruptedException e) { e.printStackTrace(); } } } } In this example, a semaphore object was created, and the initial permit was 3.Then create 10 work threads and get a license in each thread, execute work, and then release the license.Because the initial permit of the signal is 3, at the same time, only 3 threads can be obtained and the work can be obtained.Other threads need to wait for the previous thread to release the license to obtain the license and perform the work.By using the semaphore, we can limit the number of threads executed in concurrently, control the load and resource utilization of the system.