Kotlin协程runBlocking并发launch，Semaphore同步1个launch任务运行

傷城~ 2023-10-14 22:24 6阅读 0赞

## Kotlin协程runBlocking并发launch，Semaphore同步1个launch任务运行 ##

##  ##

<dependency>
                <groupId>org.jetbrains.kotlinx</groupId>
                <artifactId>kotlinx-coroutines-core</artifactId>
                <version>1.7.3</version>
                <type>pom</type>
            </dependency>

import kotlinx.coroutines.Dispatchers
    import kotlinx.coroutines.launch
    import kotlinx.coroutines.runBlocking
    import kotlinx.coroutines.sync.Semaphore
    import java.util.Collections
    
    var seq = 0
    const val times = 5
    
    fun main(args: Array<String>) {
        val size = 5 //初始容量
        var ml: MutableList<Int> = ArrayList(size)
    
        var data = Collections.synchronizedList(ml)
        val semaphore = Semaphore(1) //只有1个任务在并发环境中得到授权许可投入运行。
    
        runBlocking {
            launch(Dispatchers.IO) {
                repeat(Int.MAX_VALUE) {
                    semaphore.acquire()
    
                    myTask("A", data)
    
                    semaphore.release()
                }
            }
    
            launch(Dispatchers.IO) {
                repeat(Int.MAX_VALUE) {
                    semaphore.acquire()
    
                    myTask("B", data)
    
                    semaphore.release()
                }
            }
    
            launch(Dispatchers.IO) {
                repeat(Int.MAX_VALUE) {
                    semaphore.acquire()
    
                    myTask("C", data)
    
                    semaphore.release()
                }
            }
        }
    }
    
    //我们希望这块代码在并发环境中不受干扰的完整跑完。
    //且每轮都完整、顺序依次输出 0,1,2,3,4
    fun myTask(id: String, data: MutableList<Int>) {
        repeat(times) {
            data.add(seq++)
        }
        println("$id $data")
    
        data.clear()
        seq = 0
    }

![2ec54a16de944ff7b5ced4d7611e9760.png][]

需要注意，由于Kotlin与Java语言特性的细微差异，虽然同为Semaphore，上述代码如果引入的是 java.util.concurrent.Semaphore ，功能也能正常完成，但运行出来的结果会有小差异。Java版Semaphore会使某条线程较长时间独占CPU轮片，然后再让渡出去CPU，输出的表现就是A或B或C一大片一大片输出后才会换别的任务切入；而Kotlin版Semaphore相对更均匀的切换线程任务轮片，使得A、B、C每个任务如上图那样依次轮番运行。

[新Java线程Semaphore：并行环境下访问竞争资源控制\_zhangphil的博客-CSDN博客新Java线程Semaphore：并行环境下访问竞争资源控制Semaphore是从Java 1.5引入的Java线程新内容。Semaphore实现在线程的竞争资源访问环境下，对资源的访问控制。只有申请（acquire）得到Semaphore的许可证的线程任务可以访问竞争资源。例如： private void test() \{ // 虽然有很多线程想访问某些资源，但...![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/83410270][Java_Semaphore_zhangphil_-CSDN_Java_Semaphore_Semaphore_Java 1.5_Java_Semaphore_acquire_Semaphore_ private void test_ _ _ _..._favicon32.ico_https_blog.csdn.net_zhangphil_article_details_83410270][Java线程同步可重入锁ReentrantLock与Condition\_zhangphil的博客-CSDN博客import java.util.LinkedList;import java.util.Queue;import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.ReentrantLock;public class Main \{ private Queue...![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/92814997][Java_ReentrantLock_Condition_zhangphil_-CSDN_import java.util.LinkedList_import java.util.Queue_import java.util.concurrent.locks.Condition_import java.util.concurrent.locks.ReentrantLock_public class Main _ private Queue..._favicon32.ico_https_blog.csdn.net_zhangphil_article_details_92814997]

[Java线程同步锁ReentrantLock和Condition中断等待程序前提条件满足\_zhangphil的博客-CSDN博客import java.util.concurrent.TimeUnit;import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.ReentrantLock;/\*\* \* ReentrantLock的lock和unlock必须成对使用且把需要同步的代码块包裹起来。 \* lock-unlo...![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/92826986][Java_ReentrantLock_Condition_zhangphil_-CSDN_import java.util.concurrent.TimeUnit_import java.util.concurrent.locks.Condition_import java.util.concurrent.locks.ReentrantLock_ _ ReentrantLock_lock_unlock_ _ lock-unlo..._favicon32.ico_https_blog.csdn.net_zhangphil_article_details_92826986]

[Java线程同步与阻塞ReentrantLock - Condition替换wait - notify\_reentrantlock和wait notify\_zhangphil的博客-CSDN博客import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.ReentrantLock;public class Main \{ private ReentrantLock lock = new ReentrantLock(false); private Condition con...\_reentrantlock和wait notify![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/96360104][Java_ReentrantLock - Condition_wait - notify_reentrantlock_wait notify_zhangphil_-CSDN_import java.util.concurrent.locks.Condition_import java.util.concurrent.locks.ReentrantLock_public class Main _ private ReentrantLock lock _ new ReentrantLock_false_ private Condition con..._reentrantlock_wait notify_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_96360104]

[2ec54a16de944ff7b5ced4d7611e9760.png]: https://img-blog.csdnimg.cn/2ec54a16de944ff7b5ced4d7611e9760.png
[favicon32.ico]: https://g.csdnimg.cn/static/logo/favicon32.ico
[Java_Semaphore_zhangphil_-CSDN_Java_Semaphore_Semaphore_Java 1.5_Java_Semaphore_acquire_Semaphore_ private void test_ _ _ _..._favicon32.ico_https_blog.csdn.net_zhangphil_article_details_83410270]: https://blog.csdn.net/zhangphil/article/details/83410270
[Java_ReentrantLock_Condition_zhangphil_-CSDN_import java.util.LinkedList_import java.util.Queue_import java.util.concurrent.locks.Condition_import java.util.concurrent.locks.ReentrantLock_public class Main _ private Queue..._favicon32.ico_https_blog.csdn.net_zhangphil_article_details_92814997]: https://blog.csdn.net/zhangphil/article/details/92814997
[Java_ReentrantLock_Condition_zhangphil_-CSDN_import java.util.concurrent.TimeUnit_import java.util.concurrent.locks.Condition_import java.util.concurrent.locks.ReentrantLock_ _ ReentrantLock_lock_unlock_ _ lock-unlo..._favicon32.ico_https_blog.csdn.net_zhangphil_article_details_92826986]: https://blog.csdn.net/zhangphil/article/details/92826986
[Java_ReentrantLock - Condition_wait - notify_reentrantlock_wait notify_zhangphil_-CSDN_import java.util.concurrent.locks.Condition_import java.util.concurrent.locks.ReentrantLock_public class Main _ private ReentrantLock lock _ new ReentrantLock_false_ private Condition con..._reentrantlock_wait notify_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_96360104]: https://blog.csdn.net/zhangphil/article/details/96360104