LinkedBlockingQueue | 易学教程

Using ` LinkedBlockingQueue` may cause null pointer exception

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问题 I am learning java concurrent programming recently. I know that the final keyword can guarantee a safe publication. However, when I read the LinkedBlockingQueue source code, I found that the head and last field did not use the final keyword. I found that the enqueue method is called in the put method, and the enqueue method directly assigns the value to last.next . At this time, last may be a null because last is not declared with final . Is my understanding correct? Although lock can

Runnable locked (park) using ExecutorService and BlockingQueue

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问题 Note: I understand the rules site, but I can't to put all code (complex/large code). I wish I was more specific, but I don't know what part to extract and show. Before you close this question: Obviously, I am willing to refine my question if someone tells me where to look (technical detail). I made a video in order to show my issue. Even to formulate the question, I made a diagram to show the situation. My program has a JTree , showing the relations between Worker . I have a diagram

并发队列ConcurrentLinkedQueue和阻塞队列LinkedBlockingQueue用法

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在Java多线程应用中，队列的使用率很高，多数生产消费模型的首选数据结构就是队列。Java提供的线程安全的Queue可以分为阻塞队列和非阻塞队列，其中阻塞队列的典型例子是BlockingQueue，非阻塞队列的典型例子是ConcurrentLinkedQueue，在实际应用中要根据实际需要选用阻塞队列或者非阻塞队列。注：什么叫线程安全？这个首先要明确。线程安全就是说多线程访问同一代码，不会产生不确定的结果。 LinkedBlockingQueue 由于LinkedBlockingQueue实现是线程安全的，实现了先进先出等特性，是作为生产者消费者的首选，LinkedBlockingQueue 可以指定容量，也可以不指定，不指定的话，默认最大是Integer.MAX_VALUE，其中主要用到put和take方法，put方法在队列满的时候会阻塞直到有队列成员被消费，take方法在队列空的时候会阻塞，直到有队列成员被放进来。 package cn.thread; import java.util.concurrent.BlockingQueue; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent

JDK容器学习之Queue：LinkedBlockingQueue

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基于链表阻塞队列LinkedBlockingQueue 基于链表的无边界阻塞队列，常用与线程池创建中作为任务缓冲队列使用 I. 底层数据结构先看一下内部定义，与 ArrayBlockingQueue 做一下对比，顺带看下这两者的区别及不同的应用场景 /** 队列的容量, or Integer.MAX_VALUE if none */ private final int capacity; /** 队列中实际的个数 */ private final AtomicInteger count = new AtomicInteger(); /** * 队列头，但其中没有有效数据，它的下一个才保存实际的数据 * Head of linked list. * Invariant: head.item == null */ transient Node<E> head; /** * 队列尾，其内包含有效的数据 * Invariant: last.next == null */ private transient Node<E> last; /** 出队的锁, etc */ private final ReentrantLock takeLock = new ReentrantLock(); /** Wait queue for waiting takes */ private final