reentrantreadwritelock

current包下ReentrantReadWriteLock的使用

由 与世无争的帅哥 提交于 2020-04-12 14:02:47
ReentrantReadWriteLock中可以生产读锁和写锁。 读锁和读锁不互斥，写锁和任何读锁或者写锁都互斥。 demo：读锁和读锁不互斥 public static void main(String[] args) { ReentrantReadWriteLock reentrantReadWriteLock = new ReentrantReadWriteLock(); final ReentrantReadWriteLock.ReadLock readLock = reentrantReadWriteLock.readLock(); final ReentrantReadWriteLock.WriteLock writeLock = reentrantReadWriteLock.writeLock(); for (int i = 0; i < 5; i++) { new Thread(new Runnable() { public void run() { try { readLock.lock(); System.out.println(Thread.currentThread().getName() + " 开始读取数据"); TimeUnit.SECONDS.sleep(5); System.out.println(Thread.currentThread()

Java ReentrantReadWriteLocks - how to safely acquire write lock?

由 。_饼干妹妹 提交于 2019-12-27 18:23:01
问题 I am using in my code at the moment a ReentrantReadWriteLock to synchronize access over a tree-like structure. This structure is large, and read by many threads at once with occasional modifications to small parts of it - so it seems to fit the read-write idiom well. I understand that with this particular class, one cannot elevate a read lock to a write lock, so as per the Javadocs one must release the read lock before obtaining the write lock. I've used this pattern successfully in non

Java ReentrantReadWriteLocks - how to safely acquire write lock?

由 做~自己de王妃 提交于 2019-12-27 18:22:20
问题 I am using in my code at the moment a ReentrantReadWriteLock to synchronize access over a tree-like structure. This structure is large, and read by many threads at once with occasional modifications to small parts of it - so it seems to fit the read-write idiom well. I understand that with this particular class, one cannot elevate a read lock to a write lock, so as per the Javadocs one must release the read lock before obtaining the write lock. I've used this pattern successfully in non

How to wait for data with ReentrantReadWriteLock?

由 醉酒当歌 提交于 2019-12-24 11:00:56
问题 It is said, that ReentrantReadWriteLock is intended for one writer and multiple readers. Nevertheless, readers should wait until some data is present in the buffer. So, what to lock? I created concurrency objects like follows: private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock(); protected final Lock readLock = rwl.readLock(); protected final Lock writeLock = rwl.writeLock(); protected final Condition hasData = writeLock.newCondition(); now in write method I do: writeLock

Are read and write locks in ReentrantReadWriteLock somehow related?

由 不羁的心 提交于 2019-12-22 06:27:21
问题 Please explain me more the contract. I can't figure out if two locks contained in ReentrantReadWriteLock somehow related? Or these are just a bundle of two normal locks? 回答1: If threads are waiting Read Lock it is shared but when thread wants to acquire write lock only that thread is allowed the access same as mutual exclusion. So either one of operation is allowed . if lock is held by readers and thread request write lock no more readers are allowed to acquire read lock until thread which

Java : ReentrantReadWriteLock with priority

由 一世执手 提交于 2019-12-19 02:54:28
问题 The following is the typical reader and writer pattern (a lot of reads and few writes) private ReadWriteLock lock = new ReentrantReadWriteLock(); private int value; public void writeValue(int newValue){ lock.writeLock().lock(); try{ this.value = newValue; } finally{ lock.writeLock().unlock(); } } public int readValue(){ lock.readLock().lock(); try{ return value; } finally{ lock.writeLock().unlock(); } } I am wondering that is it possible to have priority to writer and reader ? For example,

ReentrantReadWriteLock: what's the difference between ReadLock and WriteLock?

由 元气小坏坏 提交于 2019-12-17 08:22:21
问题 What I know is: ReadLock and WriteLock affect each other somehow WriteLock is just like synchronized ReadLock seems cannot work alone 回答1: readLock.lock(); This means that if any other thread is writing (i.e. holds a write lock) then stop here until no other thread is writing. Once the lock is granted no other thread will be allowed to write (i.e. take a write lock) until the lock is released. writeLock.lock(); This means that if any other thread is reading or writing , stop here and wait

ReentrantReadWriteLock: what's the difference between ReadLock and WriteLock?

由 浪子不回头ぞ 提交于 2019-12-17 08:22:04
问题 What I know is: ReadLock and WriteLock affect each other somehow WriteLock is just like synchronized ReadLock seems cannot work alone 回答1: readLock.lock(); This means that if any other thread is writing (i.e. holds a write lock) then stop here until no other thread is writing. Once the lock is granted no other thread will be allowed to write (i.e. take a write lock) until the lock is released. writeLock.lock(); This means that if any other thread is reading or writing , stop here and wait

Resource manager with ReentrantLocks

由 依然范特西╮ 提交于 2019-12-10 17:46:21
问题 I am trying to implement a resource handler class that assigns the resources (strings, stored in an array) to multiple clients that can try to acquire the lock on a set of resources and unlock them by an ID given by the lock method. I'm trying to use fair ReentrantReadWriteLock-s, one for each resource. I only see the log of the client. There are several problems, sometimes a thread won't stop requesting and acquiring resources, sometimes deadlock happens, and sometimes the releaseLock fails.

scala collections circular buffer

由 我只是一个虾纸丫 提交于 2019-12-09 11:42:47
问题 Just messing about here, with circular buffers. Is this a sensible implementation or is there a faster/more reliable way to skin this cat? class CircularBuffer[T](size: Int)(implicit mf: Manifest[T]) { private val arr = new scala.collection.mutable.ArrayBuffer[T]() private var cursor = 0 val monitor = new ReentrantReadWriteLock() def push(value: T) { monitor.writeLock().lock() try { arr(cursor) = value cursor += 1 cursor %= size } finally { monitor.writeLock().unlock() } } def getAll: Array[T
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