Java8-Lock-No.01

本文介绍了一个简单的Java程序,该程序利用ReentrantLock来确保多个线程同时进行安全的计数操作。通过固定线程池和ReentrantLock的结合使用,演示了如何在并发环境下正确地增加共享变量。

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import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.locks.ReentrantLock;
import java.util.stream.IntStream;

public class Lock1 {

    private static final int NUM_INCREMENTS = 10000;

    private static ReentrantLock lock = new ReentrantLock();

    private static int count = 0;

    private static void increment() {
        lock.lock();
        try {
            count++;
        } finally {
            lock.unlock();
        }
    }

    public static void main(String[] args) {
        testLock();
    }

    private static void testLock() {
        count = 0;

        ExecutorService executor = Executors.newFixedThreadPool(2);

        IntStream.range(0, NUM_INCREMENTS)
                 .forEach(i -> executor.submit(Lock1::increment));

        ConcurrentUtils.stop(executor);

        System.out.println(count);
    }

}
WARNING! You are using an unsupported Java runtime. * Please use Java(TM) 21 to run Neo4j. * Please see https://neo4j.com/docs/ for Neo4j installation instructions. 2025-03-19 03:12:04.510+0000 INFO Logging config in use: File 'D:\neo4j community\neo4j-community-2025.02.0-windows\neo4j-community-2025.02.0\conf\user-logs.xml' 2025-03-19 03:12:04.526+0000 INFO Starting... 2025-03-19 03:12:06.349+0000 INFO This instance is ServerId{f31b9cbe} (f31b9cbe-9c30-40d8-9dd1-a8c08979c293) 2025-03-19 03:12:08.179+0000 INFO ======== Neo4j 2025.02.0 ======== 2025-03-19 03:12:19.405+0000 ERROR Failed to start Neo4j on localhost:7474. java.lang.RuntimeException: Error starting Neo4j database server at D:\neo4j community\neo4j-community-2025.02.0-windows\neo4j-community-2025.02.0\data\databases at org.neo4j.graphdb.facade.DatabaseManagementServiceFactory.startDatabaseServer(DatabaseManagementServiceFactory.java:293) ~[neo4j-2025.02.0.jar:2025.02.0] at org.neo4j.graphdb.facade.DatabaseManagementServiceFactory.build(DatabaseManagementServiceFactory.java:228) ~[neo4j-2025.02.0.jar:2025.02.0] at org.neo4j.server.CommunityBootstrapper.createNeo(CommunityBootstrapper.java:38) ~[neo4j-2025.02.0.jar:2025.02.0] at org.neo4j.server.NeoBootstrapper.start(NeoBootstrapper.java:190) [neo4j-2025.02.0.jar:2025.02.0] at org.neo4j.server.NeoBootstrapper.start(NeoBootstrapper.java:100) [neo4j-2025.02.0.jar:2025.02.0] at org.neo4j.server.Neo4jCommunity.main(Neo4jCommunity.java:30) [neo4j-2025.02.0.jar:2025.02.0] Caused by: org.neo4j.kernel.lifecycle.LifecycleException: Component 'org.neo4j.kernel.internal.locker.LockerLifecycleAdapter@7fae4d4a' was successfully initialized, but failed to start. Please see the attached cause exception "Lock file has been locked by another process: D:\neo4j community\neo4j-community-2025.02.0-windows\neo4j-community-2025.02.0\data\databases\store_lock. Please ensure no other process is using this database, and that the d
最新发布
03-20
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