spring 集群环境中运行的Spring Scheduled Task

Spring Scheduled Task running in clustered environment

提问by user3131879

I am writing an application that has a cron job that executes every 60 seconds. The application is configured to scale when required onto multiple instances. I only want to execute the task on 1 instance every 60 seconds (On any node). Out of the box I can not find a solution to this and I am surprised it has not been asked multiple times before. I am using Spring 4.1.6.

我正在编写一个应用程序，它有一个每 60 秒执行一次的 cron 作业。应用程序配置为在需要时扩展到多个实例。我只想每 60 秒（在任何节点上）在 1 个实例上执行任务。开箱即用，我找不到解决方案，我很惊讶之前没有多次询问它。我正在使用 Spring 4.1.6。

    <task:scheduled-tasks>
        <task:scheduled ref="beanName" method="execute" cron="0/60 * * * * *"/>
    </task:scheduled-tasks>

采纳答案by manish

Batch and scheduled jobs are typically run on their own standalone servers, away from customer facing apps so it is not a common requirement to include a job in an application that is expected to run on a cluster. Additionally, jobs in clustered environments typically do not need to worry about other instances of the same job running in parallel so another reason why isolation of job instances is not a big requirement.

批处理和计划作业通常在它们自己的独立服务器上运行，远离面向客户的应用程序，因此通常不要求将作业包含在预期在集群上运行的应用程序中。此外，集群环境中的作业通常不需要担心并行运行的同一作业的其他实例，因此隔离作业实例的另一个原因不是很大的要求。

A simple solution would be to configure your jobs inside a Spring Profile. For example, if your current configuration is:

一个简单的解决方案是在 Spring Profile 中配置您的作业。例如，如果您当前的配置是：

<beans>
  <bean id="someBean" .../>

  <task:scheduled-tasks>
    <task:scheduled ref="someBean" method="execute" cron="0/60 * * * * *"/>
  </task:scheduled-tasks>
</beans>

change it to:

将其更改为：

<beans>
  <beans profile="scheduled">
    <bean id="someBean" .../>

    <task:scheduled-tasks>
      <task:scheduled ref="someBean" method="execute" cron="0/60 * * * * *"/>
    </task:scheduled-tasks>
  </beans>
</beans>

Then, launch your application on just one machine with the scheduledprofile activated (-Dspring.profiles.active=scheduled).

然后，仅在一台已scheduled激活配置文件的机器上启动您的应用程序( -Dspring.profiles.active=scheduled)。

If the primary server becomes unavailable for some reason, just launch another server with the profile enabled and things will continue to work just fine.

如果主服务器由于某种原因变得不可用，只需启动另一台启用了配置文件的服务器，事情就会继续正常工作。

---

---

Things change if you want automatic failover for the jobs as well. Then, you will need to keep the job running on all servers and check synchronization through a common resource such as a database table, a clustered cache, a JMX variable, etc.

如果您还希望作业自动进行故障转移，情况就会发生变化。然后，您需要保持作业在所有服务器上运行，并通过公共资源（例如数据库表、集群缓存、JMX 变量等）检查同步。

回答by Lukas

There is a ShedLockproject that serves exactly this purpose. You just annotate tasks which should be locked when executed

有一个ShedLock项目正是为了这个目的。您只需注释执行时应锁定的任务

@Scheduled( ... )
@SchedulerLock(name = "scheduledTaskName")
public void scheduledTask() {
   // do something
}

Configure Spring and a LockProvider

配置 Spring 和 LockProvider

@Configuration
@EnableScheduling
@EnableSchedulerLock(defaultLockAtMostFor = "30s")
class MySpringConfiguration {
    ...
    @Bean
    public LockProvider lockProvider(DataSource dataSource) {
       return new JdbcTemplateLockProvider(dataSource);
    }
    ...
}

回答by alexanoid

I think you have to use Quartz Clustering with JDBC-JobStorefor this purpose

我认为您必须为此目的使用Quartz Clustering 和 JDBC-JobStore

回答by mspapant

The is another simple and robust way to safe execute a job in a cluster. You can based on database and execute the task only if the node is the "leader" in the cluster.

这是在集群中安全执行作业的另一种简单而强大的方法。只有当节点是集群中的“领导者”时，才能基于数据库执行任务。

Also when a node is failed or shutdown in the cluster another node became the leader.

同样，当集群中的一个节点出现故障或关闭时，另一个节点将成为领导者。

All you have is to create a "leader election" mechanism and every time to check if your are the leader:

你所要做的就是创建一个“leader选举”机制，每次检查你是否是leader：

@Scheduled(cron = "*/30 * * * * *")
public void executeFailedEmailTasks() {
    if (checkIfLeader()) {
        final List<EmailTask> list = emailTaskService.getFailedEmailTasks();
        for (EmailTask emailTask : list) {
            dispatchService.sendEmail(emailTask);
        }
    }
}

Follow those steps:

请按照以下步骤操作：

1.Define the object and table that holds one entry per node in the cluster:

1.定义集群中每个节点保存一个条目的对象和表：

@Entity(name = "SYS_NODE")
public class SystemNode {

/** The id. */
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

/** The name. */
@Column(name = "TIMESTAMP")
private String timestamp;

/** The ip. */
@Column(name = "IP")
private String ip;

/** The last ping. */
@Column(name = "LAST_PING")
private Date lastPing;

/** The last ping. */
@Column(name = "CREATED_AT")
private Date createdAt = new Date();

/** The last ping. */
@Column(name = "IS_LEADER")
private Boolean isLeader = Boolean.FALSE;

public Long getId() {
    return id;
}

public void setId(final Long id) {
    this.id = id;
}

public String getTimestamp() {
    return timestamp;
}

public void setTimestamp(final String timestamp) {
    this.timestamp = timestamp;
}

public String getIp() {
    return ip;
}

public void setIp(final String ip) {
    this.ip = ip;
}

public Date getLastPing() {
    return lastPing;
}

public void setLastPing(final Date lastPing) {
    this.lastPing = lastPing;
}

public Date getCreatedAt() {
    return createdAt;
}

public void setCreatedAt(final Date createdAt) {
    this.createdAt = createdAt;
}

public Boolean getIsLeader() {
    return isLeader;
}

public void setIsLeader(final Boolean isLeader) {
    this.isLeader = isLeader;
}

@Override
public String toString() {
    return "SystemNode{" +
            "id=" + id +
            ", timestamp='" + timestamp + '\'' +
            ", ip='" + ip + '\'' +
            ", lastPing=" + lastPing +
            ", createdAt=" + createdAt +
            ", isLeader=" + isLeader +
            '}';
}

}

}

2.Create the service that a) insert the node in database , b) check for leader

2.创建服务a）在数据库中插入节点，b）检查leader

@Service
@Transactional
public class SystemNodeServiceImpl implements SystemNodeService,    ApplicationListener {

/** The logger. */
private static final Logger LOGGER = Logger.getLogger(SystemNodeService.class);

/** The constant NO_ALIVE_NODES. */
private static final String NO_ALIVE_NODES = "Not alive nodes found in list {0}";

/** The ip. */
private String ip;

/** The system service. */
private SystemService systemService;

/** The system node repository. */
private SystemNodeRepository systemNodeRepository;

@Autowired
public void setSystemService(final SystemService systemService) {
    this.systemService = systemService;
}

@Autowired
public void setSystemNodeRepository(final SystemNodeRepository systemNodeRepository) {
    this.systemNodeRepository = systemNodeRepository;
}

@Override
public void pingNode() {
    final SystemNode node = systemNodeRepository.findByIp(ip);
    if (node == null) {
        createNode();
    } else {
        updateNode(node);
    }
}

@Override
public void checkLeaderShip() {
    final List<SystemNode> allList = systemNodeRepository.findAll();
    final List<SystemNode> aliveList = filterAliveNodes(allList);

    SystemNode leader = findLeader(allList);
    if (leader != null && aliveList.contains(leader)) {
        setLeaderFlag(allList, Boolean.FALSE);
        leader.setIsLeader(Boolean.TRUE);
        systemNodeRepository.save(allList);
    } else {
        final SystemNode node = findMinNode(aliveList);

        setLeaderFlag(allList, Boolean.FALSE);
        node.setIsLeader(Boolean.TRUE);
        systemNodeRepository.save(allList);
    }
}

/**
 * Returns the leaded
 * @param list
 *          the list
 * @return  the leader
 */
private SystemNode findLeader(final List<SystemNode> list) {
    for (SystemNode systemNode : list) {
        if (systemNode.getIsLeader()) {
            return systemNode;
        }
    }
    return null;
}

@Override
public boolean isLeader() {
    final SystemNode node = systemNodeRepository.findByIp(ip);
    return node != null && node.getIsLeader();
}

@Override
public void onApplicationEvent(final ApplicationEvent applicationEvent) {
    try {
        ip = InetAddress.getLocalHost().getHostAddress();
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
    if (applicationEvent instanceof ContextRefreshedEvent) {
        pingNode();
    }
}

/**
 * Creates the node
 */
private void createNode() {
    final SystemNode node = new SystemNode();
    node.setIp(ip);
    node.setTimestamp(String.valueOf(System.currentTimeMillis()));
    node.setCreatedAt(new Date());
    node.setLastPing(new Date());
    node.setIsLeader(CollectionUtils.isEmpty(systemNodeRepository.findAll()));
    systemNodeRepository.save(node);
}

/**
 * Updates the node
 */
private void updateNode(final SystemNode node) {
    node.setLastPing(new Date());
    systemNodeRepository.save(node);
}

/**
 * Returns the alive nodes.
 *
 * @param list
 *         the list
 * @return the alive nodes
 */
private List<SystemNode> filterAliveNodes(final List<SystemNode> list) {
    int timeout = systemService.getSetting(SettingEnum.SYSTEM_CONFIGURATION_SYSTEM_NODE_ALIVE_TIMEOUT, Integer.class);
    final List<SystemNode> finalList = new LinkedList<>();
    for (SystemNode systemNode : list) {
        if (!DateUtils.hasExpired(systemNode.getLastPing(), timeout)) {
            finalList.add(systemNode);
        }
    }
    if (CollectionUtils.isEmpty(finalList)) {
        LOGGER.warn(MessageFormat.format(NO_ALIVE_NODES, list));
        throw new RuntimeException(MessageFormat.format(NO_ALIVE_NODES, list));
    }
    return finalList;
}

/**
 * Finds the min name node.
 *
 * @param list
 *         the list
 * @return the min node
 */
private SystemNode findMinNode(final List<SystemNode> list) {
    SystemNode min = list.get(0);
    for (SystemNode systemNode : list) {
        if (systemNode.getTimestamp().compareTo(min.getTimestamp()) < -1) {
            min = systemNode;
        }
    }
    return min;
}

/**
 * Sets the leader flag.
 *
 * @param list
 *         the list
 * @param value
 *         the value
 */
private void setLeaderFlag(final List<SystemNode> list, final Boolean value) {
    for (SystemNode systemNode : list) {
        systemNode.setIsLeader(value);
    }
}

}

}

3.ping the database to send that your are alive

3.ping数据库发送你还活着

@Override
@Scheduled(cron = "0 0/5 * * * ?")
public void executeSystemNodePing() {
    systemNodeService.pingNode();
}

@Override
@Scheduled(cron = "0 0/10 * * * ?")
public void executeLeaderResolution() {
    systemNodeService.checkLeaderShip();
}

4.you are ready! Just check if you are the leader before execute the task:

4.你准备好了！在执行任务之前检查你是否是领导者：

@Override
@Scheduled(cron = "*/30 * * * * *")
public void executeFailedEmailTasks() {
    if (checkIfLeader()) {
        final List<EmailTask> list = emailTaskService.getFailedEmailTasks();
        for (EmailTask emailTask : list) {
            dispatchService.sendEmail(emailTask);
        }
    }
}

回答by Will Hughes

dlockis designed to run tasks only once by using database indexes and constraints. You can simply do something like below.

dlock旨在通过使用数据库索引和约束仅运行一次任务。您可以简单地执行以下操作。

@Scheduled(cron = "30 30 3 * * *")
@TryLock(name = "executeMyTask", owner = SERVER_NAME, lockFor = THREE_MINUTES)
public void execute() {

}

See the articleabout using it.

请参阅有关使用它的文章。

回答by RenRen

I'm using a database table to do the locking.Only one task at a time can do a insert to the table. The other one will get a DuplicateKeyException. The insert and delete logic is handeld by an aspectaround the @Scheduled annotation. I'm using Spring Boot 2.0

我正在使用数据库表来进行锁定。一次只有一项任务可以对表执行插入操作。另一个将得到 DuplicateKeyException。插入和删除逻辑由@Scheduled 注释周围的方面处理。我正在使用 Spring Boot 2.0

@Component
@Aspect
public class SchedulerLock {

    private static final Logger LOGGER = LoggerFactory.getLogger(SchedulerLock.class);

    @Autowired
    private JdbcTemplate jdbcTemplate;  

    @Around("execution(@org.springframework.scheduling.annotation.Scheduled * *(..))")
    public Object lockTask(ProceedingJoinPoint joinPoint) throws Throwable {

        String jobSignature = joinPoint.getSignature().toString();
        try {
            jdbcTemplate.update("INSERT INTO scheduler_lock (signature, date) VALUES (?, ?)", new Object[] {jobSignature, new Date()});

            Object proceed = joinPoint.proceed();

            jdbcTemplate.update("DELETE FROM scheduler_lock WHERE lock_signature = ?", new Object[] {jobSignature});
            return proceed;

        }catch (DuplicateKeyException e) {
            LOGGER.warn("Job is currently locked: "+jobSignature);
            return null;
        }
    }
}

@Component
public class EveryTenSecondJob {

    @Scheduled(cron = "0/10 * * * * *")
    public void taskExecution() {
        System.out.println("Hello World");
    }
}

CREATE TABLE scheduler_lock(
    signature varchar(255) NOT NULL,
    date datetime DEFAULT NULL,
    PRIMARY KEY(signature)
);

回答by Gustav Karlsson

You could use an embeddable scheduler like db-schedulerto accomplish this. It has persistent executions and uses a simple optimistic locking mechanism to guarantee execution by a single node.

您可以使用像db-scheduler这样的可嵌入调度程序来完成此操作。它具有持久执行并使用简单的乐观锁定机制来保证由单个节点执行。

Example code for how the use-case can be achieved:

如何实现用例的示例代码：

   RecurringTask<Void> recurring1 = Tasks.recurring("my-task-name", FixedDelay.of(Duration.ofSeconds(60)))
    .execute((taskInstance, executionContext) -> {
        System.out.println("Executing " + taskInstance.getTaskAndInstance());
    });

   final Scheduler scheduler = Scheduler
          .create(dataSource)
          .startTasks(recurring1)
          .build();

   scheduler.start();