Test on java read-write lock
package com.zang.concurrent.locks.rwlock;
import java.util.Random;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/**
* 读写锁测试
* 写锁可降级为读锁
* 读锁可重用
*
* @author Zhang Qiang
* @Date 2019/9/17 17:04
*/
public class ReadWriteLockUsage {
private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
private final Lock readLock = readWriteLock.readLock();
private final Lock writeLock = readWriteLock.writeLock();
private static StringBuilder argString = new StringBuilder();
public static void main(String[] args) {
ReadWriteLockUsage readWriteLockUsage = new ReadWriteLockUsage();
// 循环创建线程获取锁
for (int i = 0; i < 10; i++) {
long next = (long) (new Random().nextFloat() * 1000);
Thread writeThread = new Thread(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(next);
argString.delete(0,argString.length());
argString.append(next);
System.out.println(Thread.currentThread().getName() + " -> start" + ", next :" + next + ", argString:" + argString);
readWriteLockUsage.wreiter(argString.toString());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
writeThread.setName("T_"+i);
writeThread.start();
Thread readThread = new Thread(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(next);
readWriteLockUsage.reader(argString.toString());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
readThread.start();
}
}
/**
* 读锁
*
* @param argString
* @return
*/
public void wreiter(String argString){
if (writeLock.tryLock()){
try {
argString += "_" +ClassLoader.getSystemClassLoader().getParent().toString();
Thread.sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
writeLock.unlock();
System.out.println("writeLock 已释放");
}
} else {
System.out.println("未获取到写锁");
}
}
/**
* 写锁
*
* @param argString
* @return
*/
public void reader(String argString){
readLock.lock();
try {
System.out.println("readLock ============== atgString: " + argString);
} finally {
readLock.unlock();
}
}
}
Print information:
"D:\Program Files\Java\jdk1.8.0_202\bin\java.exe" "-javaagent:D:\Program Files\JetBrains\IntelliJ IDEA 2018.2.1\lib\idea_rt.jar=56588:D:\Program Files\JetBrains\IntelliJ IDEA 2018.2.1\bin" -Dfile.encoding=UTF-8 -classpath "D:\Program Files\Java\jdk1.8.0_202\jre\lib\charsets.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\deploy.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\access-bridge-64.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\cldrdata.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\dnsns.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\jaccess.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\jfxrt.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\localedata.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\nashorn.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\sunec.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\sunjce_provider.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\sunmscapi.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\sunpkcs11.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\ext\zipfs.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\javaws.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\jce.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\jfr.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\jfxswt.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\jsse.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\management-agent.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\plugin.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\resources.jar;D:\Program Files\Java\jdk1.8.0_202\jre\lib\rt.jar;D:\IdeaProject\github\nettyGui\target\classes;D:\Maven\Repository\io\netty\netty-all\5.0.0.Alpha2\netty-all-5.0.0.Alpha2.jar;D:\Maven\Repository\org\projectlombok\lombok\1.18.8\lombok-1.18.8.jar;D:\Maven\Repository\com\google\protobuf\protobuf-java\3.7.1\protobuf-java-3.7.1.jar;D:\Maven\Repository\redis\clients\jedis\2.9.0\jedis-2.9.0.jar;D:\Maven\Repository\org\apache\commons\commons-pool2\2.4.2\commons-pool2-2.4.2.jar;D:\Maven\Repository\commons-io\commons-io\2.4\commons-io-2.4.jar;D:\Maven\Repository\com\github\javafaker\javafaker\1.0.0\javafaker-1.0.0.jar;D:\Maven\Repository\org\apache\commons\commons-lang3\3.5\commons-lang3-3.5.jar;D:\Maven\Repository\org\yaml\snakeyaml\1.23\snakeyaml-1.23-android.jar;D:\Maven\Repository\com\github\mifmif\generex\1.0.2\generex-1.0.2.jar;D:\Maven\Repository\dk\brics\automaton\automaton\1.11-8\automaton-1.11-8.jar;D:\Maven\Repository\commons-configuration\commons-configuration\1.8\commons-configuration-1.8.jar;D:\Maven\Repository\commons-lang\commons-lang\2.6\commons-lang-2.6.jar;D:\Maven\Repository\commons-logging\commons-logging\1.1.1\commons-logging-1.1.1.jar;D:\Maven\Repository\org\quartz-scheduler\quartz\2.3.0\quartz-2.3.0.jar;D:\Maven\Repository\com\mchange\c3p0\0.9.5.2\c3p0-0.9.5.2.jar;D:\Maven\Repository\com\mchange\mchange-commons-java\0.2.11\mchange-commons-java-0.2.11.jar;D:\Maven\Repository\com\zaxxer\HikariCP-java6\2.3.13\HikariCP-java6-2.3.13.jar;D:\Maven\Repository\org\slf4j\slf4j-api\1.7.7\slf4j-api-1.7.7.jar;D:\Maven\Repository\org\slf4j\slf4j-nop\1.7.2\slf4j-nop-1.7.2.jar;D:\Maven\Repository\com\aliyun\aliyun-java-sdk-core\3.0.0\aliyun-java-sdk-core-3.0.0.jar;D:\Maven\Repository\com\aliyun\aliyun-java-sdk-dm\3.1.0\aliyun-java-sdk-dm-3.1.0.jar;D:\Maven\Repository\io\reactivex\rxjava\1.3.8\rxjava-1.3.8.jar" com.zang.concurrent.locks.rwlock.ReadWriteLockUsage T_9 -> Start, the Next: 18, argString: 18 readLock ============== atgString: not to get a write lock readLock ============== atgString : T_5 -> Start, the Next: 174, argString: 174 T_6 -> Start, the Next: 364, argString: 364 does not acquire a write lock writeLock released readLock ============== atgString: 174 T_8 -> Start, the Next: 529, argString: 529 T_3 -> Start, the Next: 622, argString: 622 does not acquire a write lock T_4 -> start, next: 637 , argString: 637 does not acquire a write lock T_7 -> start, next: 661, argString: 661 does not acquire a write lock readLock ============== atgString: 529 readLock ============== atgString: 622 ============== atgString readLock: 622 readLock ============== atgString: 637 writeLock released T_0 -> Start, the Next: 750, argString: 750 readLock ============== atgString: 750 does not acquire a write lock T_1 -> start, next: 773 , argString: 773 writeLock released readLock ============== atgString: 773 T_2 -> Start, the Next: 985, argString: 985 writeLock released readLock ============= atgString =: 985 Process Finished with Exit code 0