代码示例3.2

1.当读操作远远高于写操作时使用读写锁让读读可以并发来提高性能

from

3.提供一个数据容器类内部分别使用读锁保护数据的read()方法写锁保护数据的write()方法

二、读读不互斥

lombok.extern.slf4j.Slf4j;import

java.util.concurrent.locks.ReentrantReadWriteLock;Slf4j

public

ReentrantReadWriteLock();private

ReentrantReadWriteLock.ReadLock

readLock

reentrantReadWriteLock.readLock();private

ReentrantReadWriteLock.WriteLock

writeLock

reentrantReadWriteLock.writeLock();public

Object

read(){log.debug(获取读锁);readLock.lock();try

{log.debug(读取);try

{Thread.sleep(1000);}catch(Exception

data;}finally

{log.debug(释放读锁);readLock.unlock();}}public

void

write(){log.debug(获取写锁);writeLock.lock();try{log.debug(写入);}finally

{log.debug(释放写锁);writeLock.unlock();}}public

static

Thread(()-{readWriteLockLearning.read();},

t1).start();new

Thread(()-{readWriteLockLearning.read();},

t2).start();}

lombok.extern.slf4j.Slf4j;import

java.util.concurrent.locks.ReentrantReadWriteLock;Slf4j

public

ReentrantReadWriteLock();private

ReentrantReadWriteLock.ReadLock

readLock

reentrantReadWriteLock.readLock();private

ReentrantReadWriteLock.WriteLock

writeLock

reentrantReadWriteLock.writeLock();public

Object

read(){log.debug(获取读锁);readLock.lock();try

data;}finally

{log.debug(释放读锁);readLock.unlock();}}public

void

write(){log.debug(获取写锁);writeLock.lock();try{log.debug(写入);try

{Thread.sleep(1000);}catch(Exception

e){e.printStackTrace();}}finally

{log.debug(释放写锁);writeLock.unlock();}}public

static

Thread(()-{readWriteLockLearning.read();},

t1).start();try

Thread(()-{readWriteLockLearning.write();},

t2).start();}

lombok.extern.slf4j.Slf4j;import

java.util.concurrent.locks.ReentrantReadWriteLock;Slf4j

public

ReentrantReadWriteLock();private

ReentrantReadWriteLock.ReadLock

readLock

reentrantReadWriteLock.readLock();private

ReentrantReadWriteLock.WriteLock

writeLock

reentrantReadWriteLock.writeLock();public

Object

read(){log.debug(获取读锁);readLock.lock();try

data;}finally

{log.debug(释放读锁);readLock.unlock();}}public

void

write(){log.debug(获取写锁);writeLock.lock();try{log.debug(写入);try

{Thread.sleep(1000);}catch(Exception

e){e.printStackTrace();}}finally

{log.debug(释放写锁);writeLock.unlock();}}public

static

Thread(()-{readWriteLockLearning.write();},

t1).start();try

Thread(()-{readWriteLockLearning.write();},

t2).start();}

1.读锁不支持条件变量2.不支持重入时升级持有读锁的情况下去获取写锁会导致获取写锁永久等待

5.2.1

lombok.extern.slf4j.Slf4j;import

java.util.concurrent.locks.ReentrantReadWriteLock;Slf4j

public

ReentrantReadWriteLock();private

ReentrantReadWriteLock.ReadLock

readLock

reentrantReadWriteLock.readLock();private

ReentrantReadWriteLock.WriteLock

writeLock

reentrantReadWriteLock.writeLock();public

void

readWrite(){log.debug(获取读锁);readLock.lock();try

{try{log.debug(获取写锁);writeLock.lock();}finally

{log.debug(释放写锁);writeLock.unlock();}}finally

{log.debug(释放读锁);readLock.unlock();}}public

static

ReadWriteLockLearning2();readWriteLockLearning.readWrite();}

5.2.2