使用Redis实现延时任务(一)

前提

最近在生产环境刚好遇到了延时任务的场景,调研了一下目前主流的方案,分析了一下优劣并且敲定了最终的方案。这篇文章记录了调研的过程,以及初步方案的实现。

候选方案对比

下面是想到的几种实现延时任务的方案,总结了一下相应的优势和劣势。

方案 优势 劣势 选用场景
JDK内置的延迟队列DelayQueue 实现简单 数据内存态,不可靠 一致性相对低的场景
调度框架和MySQL进行短间隔轮询 实现简单,可靠性高 存在明显的性能瓶颈 数据量较少实时性相对低的场景
RabbitMQDLXTTL,一般称为死信队列方案 异步交互可以削峰 延时的时间长度不可控,如果数据需要持久化则性能会降低 -
调度框架和Redis进行短间隔轮询 数据持久化,高性能 实现难度大 常见于支付结果回调方案
时间轮 实时性高 实现难度大,内存消耗大 实时性高的场景

如果应用的数据量不高,实时性要求比较低,选用调度框架和MySQL进行短间隔轮询这个方案是最优的方案。但是笔者遇到的场景数据量相对比较大,实时性并不高,采用扫库的方案一定会对MySQL实例造成比较大的压力。记得很早之前,看过一个PPT叫《盒子科技聚合支付系统演进》,其中里面有一张图片给予笔者一点启发:

r-d-t-1st-1

里面刚好用到了调度框架和Redis进行短间隔轮询实现延时任务的方案,不过为了分摊应用的压力,图中的方案还做了分片处理。鉴于笔者当前业务紧迫,所以在第一期的方案暂时不考虑分片,只做了一个简化版的实现。

由于PPT中没有任何的代码或者框架贴出,有些需要解决的技术点需要自行思考,下面会重现一次整个方案实现的详细过程。

场景设计

实际的生产场景是笔者负责的某个系统需要对接一个外部的资金方,每一笔资金下单后需要延时30分钟推送对应的附件。这里简化为一个订单信息数据延迟处理的场景,就是每一笔下单记录一条订单消息(暂时叫做OrderMessage),订单消息需要延迟5到15秒后进行异步处理。

r-d-t-1st-2

否决的候选方案实现思路

下面介绍一下其它四个不选用的候选方案,结合一些伪代码和流程分析一下实现过程。

JDK内置延迟队列

DelayQueue是一个阻塞队列的实现,它的队列元素必须是Delayed的子类,这里做个简单的例子:

public class DelayQueueMain {

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

public static void main(String[] args) throws Exception {
DelayQueue<OrderMessage> queue = new DelayQueue<>();
// 默认延迟5秒
OrderMessage message = new OrderMessage("ORDER_ID_10086");
queue.add(message);
// 延迟6秒
message = new OrderMessage("ORDER_ID_10087", 6);
queue.add(message);
// 延迟10秒
message = new OrderMessage("ORDER_ID_10088", 10);
queue.add(message);
ExecutorService executorService = Executors.newSingleThreadExecutor(r -> {
Thread thread = new Thread(r);
thread.setName("DelayWorker");
thread.setDaemon(true);
return thread;
});
LOGGER.info("开始执行调度线程...");
executorService.execute(() -> {
while (true) {
try {
OrderMessage task = queue.take();
LOGGER.info("延迟处理订单消息,{}", task.getDescription());
} catch (Exception e) {
LOGGER.error(e.getMessage(), e);
}
}
});
Thread.sleep(Integer.MAX_VALUE);
}

private static class OrderMessage implements Delayed {

private static final DateTimeFormatter F = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

/**
* 默认延迟5000毫秒
*/
private static final long DELAY_MS = 1000L * 5;

/**
* 订单ID
*/
private final String orderId;

/**
* 创建时间戳
*/
private final long timestamp;

/**
* 过期时间
*/
private final long expire;

/**
* 描述
*/
private final String description;

public OrderMessage(String orderId, long expireSeconds) {
this.orderId = orderId;
this.timestamp = System.currentTimeMillis();
this.expire = this.timestamp + expireSeconds * 1000L;
this.description = String.format("订单[%s]-创建时间为:%s,超时时间为:%s", orderId,
LocalDateTime.ofInstant(Instant.ofEpochMilli(timestamp), ZoneId.systemDefault()).format(F),
LocalDateTime.ofInstant(Instant.ofEpochMilli(expire), ZoneId.systemDefault()).format(F));
}

public OrderMessage(String orderId) {
this.orderId = orderId;
this.timestamp = System.currentTimeMillis();
this.expire = this.timestamp + DELAY_MS;
this.description = String.format("订单[%s]-创建时间为:%s,超时时间为:%s", orderId,
LocalDateTime.ofInstant(Instant.ofEpochMilli(timestamp), ZoneId.systemDefault()).format(F),
LocalDateTime.ofInstant(Instant.ofEpochMilli(expire), ZoneId.systemDefault()).format(F));
}

public String getOrderId() {
return orderId;
}

public long getTimestamp() {
return timestamp;
}

public long getExpire() {
return expire;
}

public String getDescription() {
return description;
}

@Override
public long getDelay(TimeUnit unit) {
return unit.convert(this.expire - System.currentTimeMillis(), TimeUnit.MILLISECONDS);
}

@Override
public int compareTo(Delayed o) {
return (int) (this.getDelay(TimeUnit.MILLISECONDS) - o.getDelay(TimeUnit.MILLISECONDS));
}
}
}

注意一下,OrderMessage实现Delayed接口,关键是需要实现Delayed#getDelay()Delayed#compareTo()。运行一下main()方法:

10:16:08.240 [main] INFO club.throwable.delay.DelayQueueMain - 开始执行调度线程...
10:16:13.224 [DelayWorker] INFO club.throwable.delay.DelayQueueMain - 延迟处理订单消息,订单[ORDER_ID_10086]-创建时间为:2019-08-20 10:16:08,超时时间为:2019-08-20 10:16:13
10:16:14.237 [DelayWorker] INFO club.throwable.delay.DelayQueueMain - 延迟处理订单消息,订单[ORDER_ID_10087]-创建时间为:2019-08-20 10:16:08,超时时间为:2019-08-20 10:16:14
10:16:18.237 [DelayWorker] INFO club.throwable.delay.DelayQueueMain - 延迟处理订单消息,订单[ORDER_ID_10088]-创建时间为:2019-08-20 10:16:08,超时时间为:2019-08-20 10:16:18

调度框架 + MySQL

使用调度框架对MySQL表进行短间隔轮询是实现难度比较低的方案,通常服务刚上线,表数据不多并且实时性不高的情况下应该首选这个方案。不过要注意以下几点:

  • 注意轮询间隔不能太短,否则会对MySQL实例产生影响。
  • 注意每次查询的数量,结果集数量太多有可能会导致调度阻塞和占用应用大量内存,从而影响时效性。
  • 注意要设计状态值和最大重试次数,这样才能尽量避免大量数据积压和重复查询的问题。
  • 最好通过时间列做索引,查询指定时间范围内的数据。

引入QuartzMySQL的Java驱动包和spring-boot-starter-jdbc(这里只是为了方便用相对轻量级的框架实现,生产中可以按场景按需选择其他更合理的框架):

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.48</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
<version>2.1.7.RELEASE</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.quartz-scheduler</groupId>
<artifactId>quartz</artifactId>
<version>2.3.1</version>
<scope>test</scope>
</dependency>

假设表设计如下:

CREATE DATABASE `delayTask` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci;

USE `delayTask`;

CREATE TABLE `t_order_message`
(
id BIGINT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
order_id VARCHAR(50) NOT NULL COMMENT '订单ID',
create_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建日期时间',
edit_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '修改日期时间',
retry_times TINYINT NOT NULL DEFAULT 0 COMMENT '重试次数',
order_status TINYINT NOT NULL DEFAULT 0 COMMENT '订单状态',
INDEX idx_order_id (order_id),
INDEX idx_create_time (create_time)
) COMMENT '订单信息表';

# 写入两条测试数据
INSERT INTO t_order_message(order_id) VALUES ('10086'),('10087');

编写代码:

// 常量
public class OrderConstants {

public static final int MAX_RETRY_TIMES = 5;

public static final int PENDING = 0;

public static final int SUCCESS = 1;

public static final int FAIL = -1;

public static final int LIMIT = 10;
}

// 实体
@Builder
@Data
public class OrderMessage {

private Long id;
private String orderId;
private LocalDateTime createTime;
private LocalDateTime editTime;
private Integer retryTimes;
private Integer orderStatus;
}

// DAO
@RequiredArgsConstructor
public class OrderMessageDao {

private final JdbcTemplate jdbcTemplate;

private static final ResultSetExtractor<List<OrderMessage>> M = r -> {
List<OrderMessage> list = Lists.newArrayList();
while (r.next()) {
list.add(OrderMessage.builder()
.id(r.getLong("id"))
.orderId(r.getString("order_id"))
.createTime(r.getTimestamp("create_time").toLocalDateTime())
.editTime(r.getTimestamp("edit_time").toLocalDateTime())
.retryTimes(r.getInt("retry_times"))
.orderStatus(r.getInt("order_status"))
.build());
}
return list;
};

public List<OrderMessage> selectPendingRecords(LocalDateTime start,
LocalDateTime end,
List<Integer> statusList,
int maxRetryTimes,
int limit) {
StringJoiner joiner = new StringJoiner(",");
statusList.forEach(s -> joiner.add(String.valueOf(s)));
return jdbcTemplate.query("SELECT * FROM t_order_message WHERE create_time >= ? AND create_time <= ? " +
"AND order_status IN (?) AND retry_times < ? LIMIT ?",
p -> {
p.setTimestamp(1, Timestamp.valueOf(start));
p.setTimestamp(2, Timestamp.valueOf(end));
p.setString(3, joiner.toString());
p.setInt(4, maxRetryTimes);
p.setInt(5, limit);
}, M);
}

public int updateOrderStatus(Long id, int status) {
return jdbcTemplate.update("UPDATE t_order_message SET order_status = ?,edit_time = ? WHERE id =?",
p -> {
p.setInt(1, status);
p.setTimestamp(2, Timestamp.valueOf(LocalDateTime.now()));
p.setLong(3, id);
});
}
}

// Service
@RequiredArgsConstructor
public class OrderMessageService {

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

private final OrderMessageDao orderMessageDao;

private static final List<Integer> STATUS = Lists.newArrayList();

static {
STATUS.add(OrderConstants.PENDING);
STATUS.add(OrderConstants.FAIL);
}

public void executeDelayJob() {
LOGGER.info("订单处理定时任务开始执行......");
LocalDateTime end = LocalDateTime.now();
// 一天前
LocalDateTime start = end.minusDays(1);
List<OrderMessage> list = orderMessageDao.selectPendingRecords(start, end, STATUS, OrderConstants.MAX_RETRY_TIMES, OrderConstants.LIMIT);
if (!list.isEmpty()) {
for (OrderMessage m : list) {
LOGGER.info("处理订单[{}],状态由{}更新为{}", m.getOrderId(), m.getOrderStatus(), OrderConstants.SUCCESS);
// 这里其实可以优化为批量更新
orderMessageDao.updateOrderStatus(m.getId(), OrderConstants.SUCCESS);
}
}
LOGGER.info("订单处理定时任务开始完毕......");
}
}

// Job
@DisallowConcurrentExecution
public class OrderMessageDelayJob implements Job {

@Override
public void execute(JobExecutionContext jobExecutionContext) throws JobExecutionException {
OrderMessageService service = (OrderMessageService) jobExecutionContext.getMergedJobDataMap().get("orderMessageService");
service.executeDelayJob();
}

public static void main(String[] args) throws Exception {
HikariConfig config = new HikariConfig();
config.setJdbcUrl("jdbc:mysql://localhost:3306/delayTask?useSSL=false&characterEncoding=utf8");
config.setDriverClassName(Driver.class.getName());
config.setUsername("root");
config.setPassword("root");
HikariDataSource dataSource = new HikariDataSource(config);
OrderMessageDao orderMessageDao = new OrderMessageDao(new JdbcTemplate(dataSource));
OrderMessageService service = new OrderMessageService(orderMessageDao);
// 内存模式的调度器
StdSchedulerFactory factory = new StdSchedulerFactory();
Scheduler scheduler = factory.getScheduler();
// 这里没有用到IOC容器,直接用Quartz数据集合传递服务引用
JobDataMap jobDataMap = new JobDataMap();
jobDataMap.put("orderMessageService", service);
// 新建Job
JobDetail job = JobBuilder.newJob(OrderMessageDelayJob.class)
.withIdentity("orderMessageDelayJob", "delayJob")
.usingJobData(jobDataMap)
.build();
// 新建触发器,10秒执行一次
Trigger trigger = TriggerBuilder.newTrigger()
.withIdentity("orderMessageDelayTrigger", "delayJob")
.withSchedule(SimpleScheduleBuilder.simpleSchedule().withIntervalInSeconds(10).repeatForever())
.build();
scheduler.scheduleJob(job, trigger);
// 启动调度器
scheduler.start();
Thread.sleep(Integer.MAX_VALUE);
}
}

这个例子里面用了create_time做轮询,实际上可以添加一个调度时间schedule_time列做轮询,这样子才能更容易定制空闲时和忙碌时候的调度策略。上面的示例的运行效果如下:

11:58:27.202 [main] INFO org.quartz.core.QuartzScheduler - Scheduler meta-data: Quartz Scheduler (v2.3.1) 'DefaultQuartzScheduler' with instanceId 'NON_CLUSTERED'
Scheduler class: 'org.quartz.core.QuartzScheduler' - running locally.
NOT STARTED.
Currently in standby mode.
Number of jobs executed: 0
Using thread pool 'org.quartz.simpl.SimpleThreadPool' - with 10 threads.
Using job-store 'org.quartz.simpl.RAMJobStore' - which does not support persistence. and is not clustered.

11:58:27.202 [main] INFO org.quartz.impl.StdSchedulerFactory - Quartz scheduler 'DefaultQuartzScheduler' initialized from default resource file in Quartz package: 'quartz.properties'
11:58:27.202 [main] INFO org.quartz.impl.StdSchedulerFactory - Quartz scheduler version: 2.3.1
11:58:27.209 [main] INFO org.quartz.core.QuartzScheduler - Scheduler DefaultQuartzScheduler_$_NON_CLUSTERED started.
11:58:27.212 [DefaultQuartzScheduler_QuartzSchedulerThread] DEBUG org.quartz.core.QuartzSchedulerThread - batch acquisition of 1 triggers
11:58:27.217 [DefaultQuartzScheduler_QuartzSchedulerThread] DEBUG org.quartz.simpl.PropertySettingJobFactory - Producing instance of Job 'delayJob.orderMessageDelayJob', class=club.throwable.jdbc.OrderMessageDelayJob
11:58:27.219 [HikariPool-1 connection adder] DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection com.mysql.jdbc.JDBC4Connection@10eb8c53
11:58:27.220 [DefaultQuartzScheduler_QuartzSchedulerThread] DEBUG org.quartz.core.QuartzSchedulerThread - batch acquisition of 0 triggers
11:58:27.221 [DefaultQuartzScheduler_Worker-1] DEBUG org.quartz.core.JobRunShell - Calling execute on job delayJob.orderMessageDelayJob
11:58:34.440 [DefaultQuartzScheduler_Worker-1] INFO club.throwable.jdbc.OrderMessageService - 订单处理定时任务开始执行......
11:58:34.451 [HikariPool-1 connection adder] DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection com.mysql.jdbc.JDBC4Connection@3d27ece4
11:58:34.459 [HikariPool-1 connection adder] DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection com.mysql.jdbc.JDBC4Connection@64e808af
11:58:34.470 [HikariPool-1 connection adder] DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection com.mysql.jdbc.JDBC4Connection@79c8c2b7
11:58:34.477 [HikariPool-1 connection adder] DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection com.mysql.jdbc.JDBC4Connection@19a62369
11:58:34.485 [HikariPool-1 connection adder] DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection com.mysql.jdbc.JDBC4Connection@1673d017
11:58:34.485 [HikariPool-1 connection adder] DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - After adding stats (total=10, active=0, idle=10, waiting=0)
11:58:34.559 [DefaultQuartzScheduler_Worker-1] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL query
11:58:34.565 [DefaultQuartzScheduler_Worker-1] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL statement [SELECT * FROM t_order_message WHERE create_time >= ? AND create_time <= ? AND order_status IN (?) AND retry_times < ? LIMIT ?]
11:58:34.645 [DefaultQuartzScheduler_Worker-1] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Fetching JDBC Connection from DataSource
11:58:35.210 [DefaultQuartzScheduler_Worker-1] DEBUG org.springframework.jdbc.core.JdbcTemplate - SQLWarning ignored: SQL state '22007', error code '1292', message [Truncated incorrect DOUBLE value: '0,-1']
11:58:35.335 [DefaultQuartzScheduler_Worker-1] INFO club.throwable.jdbc.OrderMessageService - 处理订单[10086],状态由0更新为1
11:58:35.342 [DefaultQuartzScheduler_Worker-1] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL update
11:58:35.346 [DefaultQuartzScheduler_Worker-1] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL statement [UPDATE t_order_message SET order_status = ?,edit_time = ? WHERE id =?]
11:58:35.347 [DefaultQuartzScheduler_Worker-1] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Fetching JDBC Connection from DataSource
11:58:35.354 [DefaultQuartzScheduler_Worker-1] INFO club.throwable.jdbc.OrderMessageService - 处理订单[10087],状态由0更新为1
11:58:35.355 [DefaultQuartzScheduler_Worker-1] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL update
11:58:35.355 [DefaultQuartzScheduler_Worker-1] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL statement [UPDATE t_order_message SET order_status = ?,edit_time = ? WHERE id =?]
11:58:35.355 [DefaultQuartzScheduler_Worker-1] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Fetching JDBC Connection from DataSource
11:58:35.361 [DefaultQuartzScheduler_Worker-1] INFO club.throwable.jdbc.OrderMessageService - 订单处理定时任务开始完毕......
11:58:35.363 [DefaultQuartzScheduler_QuartzSchedulerThread] DEBUG org.quartz.core.QuartzSchedulerThread - batch acquisition of 1 triggers
11:58:37.206 [DefaultQuartzScheduler_QuartzSchedulerThread] DEBUG org.quartz.simpl.PropertySettingJobFactory - Producing instance of Job 'delayJob.orderMessageDelayJob', class=club.throwable.jdbc.OrderMessageDelayJob
11:58:37.206 [DefaultQuartzScheduler_QuartzSchedulerThread] DEBUG org.quartz.core.QuartzSchedulerThread - batch acquisition of 0 triggers

RabbitMQ死信队列

使用RabbitMQ死信队列依赖于RabbitMQ的两个特性:TTLDLX

  • TTLTime To Live,消息存活时间,包括两个维度:队列消息存活时间和消息本身的存活时间。
  • DLXDead Letter Exchange,死信交换器。

画个图描述一下这两个特性:

r-d-t-1st-3

下面为了简单起见,TTL使用了针对队列的维度。引入RabbitMQ的Java驱动:

<dependency>
<groupId>com.rabbitmq</groupId>
<artifactId>amqp-client</artifactId>
<version>5.7.3</version>
<scope>test</scope>
</dependency>

代码如下:

public class DlxMain {

private static final DateTimeFormatter F = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
private static final Logger LOGGER = LoggerFactory.getLogger(DlxMain.class);

public static void main(String[] args) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
Connection connection = factory.newConnection();
Channel producerChannel = connection.createChannel();
Channel consumerChannel = connection.createChannel();
// dlx交换器名称为dlx.exchange,类型是direct,绑定键为dlx.key,队列名为dlx.queue
producerChannel.exchangeDeclare("dlx.exchange", "direct");
producerChannel.queueDeclare("dlx.queue", false, false, false, null);
producerChannel.queueBind("dlx.queue", "dlx.exchange", "dlx.key");
Map<String, Object> queueArgs = new HashMap<>();
// 设置队列消息过期时间,5秒
queueArgs.put("x-message-ttl", 5000);
// 指定DLX相关参数
queueArgs.put("x-dead-letter-exchange", "dlx.exchange");
queueArgs.put("x-dead-letter-routing-key", "dlx.key");
// 声明业务队列
producerChannel.queueDeclare("business.queue", false, false, false, queueArgs);
ExecutorService executorService = Executors.newSingleThreadExecutor(r -> {
Thread thread = new Thread(r);
thread.setDaemon(true);
thread.setName("DlxConsumer");
return thread;
});
// 启动消费者
executorService.execute(() -> {
try {
consumerChannel.basicConsume("dlx.queue", true, new DlxConsumer(consumerChannel));
} catch (IOException e) {
LOGGER.error(e.getMessage(), e);
}
});
OrderMessage message = new OrderMessage("10086");
producerChannel.basicPublish("", "business.queue", MessageProperties.TEXT_PLAIN,
message.getDescription().getBytes(StandardCharsets.UTF_8));
LOGGER.info("发送消息成功,订单ID:{}", message.getOrderId());

message = new OrderMessage("10087");
producerChannel.basicPublish("", "business.queue", MessageProperties.TEXT_PLAIN,
message.getDescription().getBytes(StandardCharsets.UTF_8));
LOGGER.info("发送消息成功,订单ID:{}", message.getOrderId());

message = new OrderMessage("10088");
producerChannel.basicPublish("", "business.queue", MessageProperties.TEXT_PLAIN,
message.getDescription().getBytes(StandardCharsets.UTF_8));
LOGGER.info("发送消息成功,订单ID:{}", message.getOrderId());

Thread.sleep(Integer.MAX_VALUE);
}

private static class DlxConsumer extends DefaultConsumer {

DlxConsumer(Channel channel) {
super(channel);
}

@Override
public void handleDelivery(String consumerTag,
Envelope envelope,
AMQP.BasicProperties properties,
byte[] body) throws IOException {
LOGGER.info("处理消息成功:{}", new String(body, StandardCharsets.UTF_8));
}
}

private static class OrderMessage {

private final String orderId;
private final long timestamp;
private final String description;

OrderMessage(String orderId) {
this.orderId = orderId;
this.timestamp = System.currentTimeMillis();
this.description = String.format("订单[%s],订单创建时间为:%s", orderId,
LocalDateTime.ofInstant(Instant.ofEpochMilli(timestamp), ZoneId.systemDefault()).format(F));
}

public String getOrderId() {
return orderId;
}

public long getTimestamp() {
return timestamp;
}

public String getDescription() {
return description;
}
}
}

运行main()方法结果如下:

16:35:58.638 [main] INFO club.throwable.dlx.DlxMain - 发送消息成功,订单ID:10086
16:35:58.641 [main] INFO club.throwable.dlx.DlxMain - 发送消息成功,订单ID:10087
16:35:58.641 [main] INFO club.throwable.dlx.DlxMain - 发送消息成功,订单ID:10088
16:36:03.646 [pool-1-thread-4] INFO club.throwable.dlx.DlxMain - 处理消息成功:订单[10086],订单创建时间为:2019-08-20 16:35:58
16:36:03.670 [pool-1-thread-5] INFO club.throwable.dlx.DlxMain - 处理消息成功:订单[10087],订单创建时间为:2019-08-20 16:35:58
16:36:03.670 [pool-1-thread-6] INFO club.throwable.dlx.DlxMain - 处理消息成功:订单[10088],订单创建时间为:2019-08-20 16:35:58

时间轮

时间轮TimingWheel是一种高效、低延迟的调度数据结构,底层采用数组实现存储任务列表的环形队列,示意图如下:

r-d-t-1st-4

这里暂时不对时间轮和其实现作分析,只简单举例说明怎么使用时间轮实现延时任务。这里使用Netty提供的HashedWheelTimer,引入依赖:

<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-common</artifactId>
<version>4.1.39.Final</version>
</dependency>

代码如下:

public class HashedWheelTimerMain {

private static final DateTimeFormatter F = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS");

public static void main(String[] args) throws Exception {
AtomicInteger counter = new AtomicInteger();
ThreadFactory factory = r -> {
Thread thread = new Thread(r);
thread.setDaemon(true);
thread.setName("HashedWheelTimerWorker-" + counter.getAndIncrement());
return thread;
};
// tickDuration - 每tick一次的时间间隔, 每tick一次就会到达下一个槽位
// unit - tickDuration的时间单位
// ticksPerWhee - 时间轮中的槽位数
Timer timer = new HashedWheelTimer(factory, 1, TimeUnit.SECONDS, 60);
TimerTask timerTask = new DefaultTimerTask("10086");
timer.newTimeout(timerTask, 5, TimeUnit.SECONDS);
timerTask = new DefaultTimerTask("10087");
timer.newTimeout(timerTask, 10, TimeUnit.SECONDS);
timerTask = new DefaultTimerTask("10088");
timer.newTimeout(timerTask, 15, TimeUnit.SECONDS);
Thread.sleep(Integer.MAX_VALUE);
}

private static class DefaultTimerTask implements TimerTask {

private final String orderId;
private final long timestamp;

public DefaultTimerTask(String orderId) {
this.orderId = orderId;
this.timestamp = System.currentTimeMillis();
}

@Override
public void run(Timeout timeout) throws Exception {
System.out.println(String.format("任务执行时间:%s,订单创建时间:%s,订单ID:%s",
LocalDateTime.now().format(F), LocalDateTime.ofInstant(Instant.ofEpochMilli(timestamp), ZoneId.systemDefault()).format(F), orderId));
}
}
}

运行结果:

任务执行时间:2019-08-20 17:19:49.310,订单创建时间:2019-08-20 17:19:43.294,订单ID:10086
任务执行时间:2019-08-20 17:19:54.297,订单创建时间:2019-08-20 17:19:43.301,订单ID:10087
任务执行时间:2019-08-20 17:19:59.297,订单创建时间:2019-08-20 17:19:43.301,订单ID:10088

一般来说,任务执行的时候应该使用另外的业务线程池,以免阻塞时间轮本身的运动。

选用的方案实现过程

最终选用了基于Redis的有序集合Sorted SetQuartz短轮询进行实现。具体方案是:

  1. 订单创建的时候,订单ID和当前时间戳分别作为Sorted Set的member和score添加到订单队列Sorted Set中。
  2. 订单创建的时候,订单ID和推送内容JSON字符串分别作为field和value添加到订单队列内容Hash中。
  3. 第1步和第2步操作的时候用Lua脚本保证原子性。
  4. 使用一个异步线程通过Sorted Set的命令ZREVRANGEBYSCORE弹出指定数量的订单ID对应的订单队列内容Hash中的订单推送内容数据进行处理。

对于第4点处理有两种方案:

  • 方案一:弹出订单内容数据的同时进行数据删除,也就是ZREVRANGEBYSCOREZREMHDEL命令要在同一个Lua脚本中执行,这样的话Lua脚本的编写难度大,并且由于弹出数据已经在Redis中删除,如果数据处理失败则可能需要从数据库重新查询补偿。
  • 方案二:弹出订单内容数据之后,在数据处理完成的时候再主动删除订单队列Sorted Set和订单队列内容Hash中对应的数据,这样的话需要控制并发,有重复执行的可能性。

最终暂时选用了方案一,也就是从Sorted Set弹出订单ID并且从Hash中获取完推送数据之后马上删除这两个集合中对应的数据。方案的流程图大概是这样:

r-d-t-1st-5

这里先详细说明一下用到的Redis命令。

Sorted Set相关命令

  • ZADD命令 - 将一个或多个成员元素及其分数值加入到有序集当中。

ZADD KEY SCORE1 VALUE1.. SCOREN VALUEN


  • ZREVRANGEBYSCORE命令 - 返回有序集中指定分数区间内的所有的成员。有序集成员按分数值递减(从大到小)的次序排列。

ZREVRANGEBYSCORE key max min [WITHSCORES] [LIMIT offset count]

  • max:分数区间 - 最大分数。
  • min:分数区间 - 最小分数。
  • WITHSCORES:可选参数,是否返回分数值,指定则会返回得分值。
  • LIMIT:可选参数,offset和count原理和MySQLLIMIT offset,size一致,如果不指定此参数则返回整个集合的数据。

  • ZREM命令 - 用于移除有序集中的一个或多个成员,不存在的成员将被忽略。

ZREM key member [member ...]

Hash相关命令

  • HMSET命令 - 同时将多个field-value(字段-值)对设置到哈希表中。

HMSET KEY_NAME FIELD1 VALUE1 ...FIELDN VALUEN


  • HDEL命令 - 删除哈希表key中的一个或多个指定字段,不存在的字段将被忽略。

HDEL KEY_NAME FIELD1.. FIELDN

Lua相关

  • 加载Lua脚本并且返回脚本的SHA-1字符串:SCRIPT LOAD script
  • 执行已经加载的Lua脚本:EVALSHA sha1 numkeys key [key ...] arg [arg ...]
  • unpack函数可以把table类型的参数转化为可变参数,不过需要注意的是unpack函数必须使用在非变量定义的函数调用的最后一个参数,否则会失效,详细见Stackoverflow的提问table.unpack() only returns the first element

PS:如果不熟悉Lua语言,建议系统学习一下,因为想用好Redis,一定离不开Lua。

引入依赖:

<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>2.1.7.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>

<dependencies>
<dependency>
<groupId>org.quartz-scheduler</groupId>
<artifactId>quartz</artifactId>
<version>2.3.1</version>
</dependency>
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>3.1.0</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>5.1.9.RELEASE</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.8</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.59</version>
</dependency>
</dependencies>

编写Lua脚本/lua/enqueue.lua/lua/dequeue.lua

-- /lua/enqueue.lua
local zset_key = KEYS[1]
local hash_key = KEYS[2]
local zset_value = ARGV[1]
local zset_score = ARGV[2]
local hash_field = ARGV[3]
local hash_value = ARGV[4]
redis.call('ZADD', zset_key, zset_score, zset_value)
redis.call('HSET', hash_key, hash_field, hash_value)
return nil

-- /lua/dequeue.lua
-- 参考jesque的部分Lua脚本实现
local zset_key = KEYS[1]
local hash_key = KEYS[2]
local min_score = ARGV[1]
local max_score = ARGV[2]
local offset = ARGV[3]
local limit = ARGV[4]
-- TYPE命令的返回结果是{'ok':'zset'}这样子,这里利用next做一轮迭代
local status, type = next(redis.call('TYPE', zset_key))
if status ~= nil and status == 'ok' then
if type == 'zset' then
local list = redis.call('ZREVRANGEBYSCORE', zset_key, max_score, min_score, 'LIMIT', offset, limit)
if list ~= nil and #list > 0 then
-- unpack函数能把table转化为可变参数
redis.call('ZREM', zset_key, unpack(list))
local result = redis.call('HMGET', hash_key, unpack(list))
redis.call('HDEL', hash_key, unpack(list))
return result
end
end
end
return nil

编写核心API代码:

// Jedis提供者
@Component
public class JedisProvider implements InitializingBean {

private JedisPool jedisPool;

@Override
public void afterPropertiesSet() throws Exception {
jedisPool = new JedisPool();
}

public Jedis provide(){
return jedisPool.getResource();
}
}

// OrderMessage
@Data
public class OrderMessage {

private String orderId;
private BigDecimal amount;
private Long userId;
}

// 延迟队列接口
public interface OrderDelayQueue {

void enqueue(OrderMessage message);

List<OrderMessage> dequeue(String min, String max, String offset, String limit);

List<OrderMessage> dequeue();

String enqueueSha();

String dequeueSha();
}

// 延迟队列实现类
@RequiredArgsConstructor
@Component
public class RedisOrderDelayQueue implements OrderDelayQueue, InitializingBean {

private static final String MIN_SCORE = "0";
private static final String OFFSET = "0";
private static final String LIMIT = "10";
private static final String ORDER_QUEUE = "ORDER_QUEUE";
private static final String ORDER_DETAIL_QUEUE = "ORDER_DETAIL_QUEUE";
private static final String ENQUEUE_LUA_SCRIPT_LOCATION = "/lua/enqueue.lua";
private static final String DEQUEUE_LUA_SCRIPT_LOCATION = "/lua/dequeue.lua";
private static final AtomicReference<String> ENQUEUE_LUA_SHA = new AtomicReference<>();
private static final AtomicReference<String> DEQUEUE_LUA_SHA = new AtomicReference<>();
private static final List<String> KEYS = Lists.newArrayList();

private final JedisProvider jedisProvider;

static {
KEYS.add(ORDER_QUEUE);
KEYS.add(ORDER_DETAIL_QUEUE);
}

@Override
public void enqueue(OrderMessage message) {
List<String> args = Lists.newArrayList();
args.add(message.getOrderId());
args.add(String.valueOf(System.currentTimeMillis()));
args.add(message.getOrderId());
args.add(JSON.toJSONString(message));
try (Jedis jedis = jedisProvider.provide()) {
jedis.evalsha(ENQUEUE_LUA_SHA.get(), KEYS, args);
}
}

@Override
public List<OrderMessage> dequeue() {
// 30分钟之前
String maxScore = String.valueOf(System.currentTimeMillis() - 30 * 60 * 1000);
return dequeue(MIN_SCORE, maxScore, OFFSET, LIMIT);
}

@SuppressWarnings("unchecked")
@Override
public List<OrderMessage> dequeue(String min, String max, String offset, String limit) {
List<String> args = new ArrayList<>();
args.add(min);
args.add(max);
args.add(offset);
args.add(limit);
List<OrderMessage> result = Lists.newArrayList();
try (Jedis jedis = jedisProvider.provide()) {
List<String> eval = (List<String>) jedis.evalsha(DEQUEUE_LUA_SHA.get(), KEYS, args);
if (null != eval) {
for (String e : eval) {
result.add(JSON.parseObject(e, OrderMessage.class));
}
}
}
return result;
}

@Override
public String enqueueSha() {
return ENQUEUE_LUA_SHA.get();
}

@Override
public String dequeueSha() {
return DEQUEUE_LUA_SHA.get();
}

@Override
public void afterPropertiesSet() throws Exception {
// 加载Lua脚本
loadLuaScript();
}

private void loadLuaScript() throws Exception {
try (Jedis jedis = jedisProvider.provide()) {
ClassPathResource resource = new ClassPathResource(ENQUEUE_LUA_SCRIPT_LOCATION);
String luaContent = StreamUtils.copyToString(resource.getInputStream(), StandardCharsets.UTF_8);
String sha = jedis.scriptLoad(luaContent);
ENQUEUE_LUA_SHA.compareAndSet(null, sha);
resource = new ClassPathResource(DEQUEUE_LUA_SCRIPT_LOCATION);
luaContent = StreamUtils.copyToString(resource.getInputStream(), StandardCharsets.UTF_8);
sha = jedis.scriptLoad(luaContent);
DEQUEUE_LUA_SHA.compareAndSet(null, sha);
}
}

public static void main(String[] as) throws Exception {
DateTimeFormatter f = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS");
JedisProvider jedisProvider = new JedisProvider();
jedisProvider.afterPropertiesSet();
RedisOrderDelayQueue queue = new RedisOrderDelayQueue(jedisProvider);
queue.afterPropertiesSet();
// 写入测试数据
OrderMessage message = new OrderMessage();
message.setAmount(BigDecimal.valueOf(10086));
message.setOrderId("ORDER_ID_10086");
message.setUserId(10086L);
message.setTimestamp(LocalDateTime.now().format(f));
List<String> args = Lists.newArrayList();
args.add(message.getOrderId());
// 测试需要,score设置为30分钟之前
args.add(String.valueOf(System.currentTimeMillis() - 30 * 60 * 1000));
args.add(message.getOrderId());
args.add(JSON.toJSONString(message));
try (Jedis jedis = jedisProvider.provide()) {
jedis.evalsha(ENQUEUE_LUA_SHA.get(), KEYS, args);
}
List<OrderMessage> dequeue = queue.dequeue();
System.out.println(dequeue);
}
}

这里先执行一次main()方法验证一下延迟队列是否生效:

[OrderMessage(orderId=ORDER_ID_10086, amount=10086, userId=10086, timestamp=2019-08-21 08:32:22.885)]

确定延迟队列的代码没有问题,接着编写一个QuartzJob类型的消费者OrderMessageConsumer

@DisallowConcurrentExecution
@Component
public class OrderMessageConsumer implements Job {

private static final AtomicInteger COUNTER = new AtomicInteger();
private static final ExecutorService BUSINESS_WORKER_POOL = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors(), r -> {
Thread thread = new Thread(r);
thread.setDaemon(true);
thread.setName("OrderMessageConsumerWorker-" + COUNTER.getAndIncrement());
return thread;
});
private static final Logger LOGGER = LoggerFactory.getLogger(OrderMessageConsumer.class);

@Autowired
private OrderDelayQueue orderDelayQueue;

@Override
public void execute(JobExecutionContext jobExecutionContext) throws JobExecutionException {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
LOGGER.info("订单消息处理定时任务开始执行......");
List<OrderMessage> messages = orderDelayQueue.dequeue();
if (!messages.isEmpty()) {
// 简单的列表等分放到线程池中执行
List<List<OrderMessage>> partition = Lists.partition(messages, 2);
int size = partition.size();
final CountDownLatch latch = new CountDownLatch(size);
for (List<OrderMessage> p : partition) {
BUSINESS_WORKER_POOL.execute(new ConsumeTask(p, latch));
}
try {
latch.await();
} catch (InterruptedException ignore) {
//ignore
}
}
stopWatch.stop();
LOGGER.info("订单消息处理定时任务执行完毕,耗时:{} ms......", stopWatch.getTotalTimeMillis());
}

@RequiredArgsConstructor
private static class ConsumeTask implements Runnable {

private final List<OrderMessage> messages;
private final CountDownLatch latch;

@Override
public void run() {
try {
// 实际上这里应该单条捕获异常
for (OrderMessage message : messages) {
LOGGER.info("处理订单信息,内容:{}", message);
}
} finally {
latch.countDown();
}
}
}
}

上面的消费者设计的时候需要有以下考量:

  • 使用@DisallowConcurrentExecution注解不允许Job并发执行,其实多个Job并发执行意义不大,因为我们采用的是短间隔的轮询,而Redis是单线程处理命令,在客户端做多线程其实效果不佳。
  • 线程池BUSINESS_WORKER_POOL的线程容量或者队列应该综合LIMIT值、等分订单信息列表中使用的size值以及ConsumeTask里面具体的执行时间进行考虑,这里只是为了方便使用了固定容量的线程池。
  • ConsumeTask中应该对每一条订单信息的处理单独捕获异常和吞并异常,或者把处理单个订单信息的逻辑封装成一个不抛出异常的方法。

其他Quartz相关的代码:

// Quartz配置类
@Configuration
public class QuartzAutoConfiguration {

@Bean
public SchedulerFactoryBean schedulerFactoryBean(QuartzAutowiredJobFactory quartzAutowiredJobFactory) {
SchedulerFactoryBean factory = new SchedulerFactoryBean();
factory.setAutoStartup(true);
factory.setJobFactory(quartzAutowiredJobFactory);
return factory;
}

@Bean
public QuartzAutowiredJobFactory quartzAutowiredJobFactory() {
return new QuartzAutowiredJobFactory();
}

public static class QuartzAutowiredJobFactory extends AdaptableJobFactory implements BeanFactoryAware {

private AutowireCapableBeanFactory autowireCapableBeanFactory;

@Override
public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
this.autowireCapableBeanFactory = (AutowireCapableBeanFactory) beanFactory;
}

@Override
protected Object createJobInstance(TriggerFiredBundle bundle) throws Exception {
Object jobInstance = super.createJobInstance(bundle);
// 这里利用AutowireCapableBeanFactory从新建的Job实例做一次自动装配,得到一个原型(prototype)的JobBean实例
autowireCapableBeanFactory.autowireBean(jobInstance);
return jobInstance;
}
}
}

这里暂时使用了内存态的RAMJobStore去存放任务和触发器的相关信息,如果在生产环境最好替换成基于MySQL也就是JobStoreTX进行集群化,最后是启动函数和CommandLineRunner的实现:

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class, TransactionAutoConfiguration.class})
public class Application implements CommandLineRunner {

@Autowired
private Scheduler scheduler;

@Autowired
private JedisProvider jedisProvider;

public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}

@Override
public void run(String... args) throws Exception {
// 准备一些测试数据
prepareOrderMessageData();
JobDetail job = JobBuilder.newJob(OrderMessageConsumer.class)
.withIdentity("OrderMessageConsumer", "DelayTask")
.build();
// 触发器5秒触发一次
Trigger trigger = TriggerBuilder.newTrigger()
.withIdentity("OrderMessageConsumerTrigger", "DelayTask")
.withSchedule(SimpleScheduleBuilder.simpleSchedule().withIntervalInSeconds(5).repeatForever())
.build();
scheduler.scheduleJob(job, trigger);
}

private void prepareOrderMessageData() throws Exception {
DateTimeFormatter f = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS");
try (Jedis jedis = jedisProvider.provide()) {
List<OrderMessage> messages = Lists.newArrayList();
for (int i = 0; i < 100; i++) {
OrderMessage message = new OrderMessage();
message.setAmount(BigDecimal.valueOf(i));
message.setOrderId("ORDER_ID_" + i);
message.setUserId((long) i);
message.setTimestamp(LocalDateTime.now().format(f));
messages.add(message);
}
// 这里暂时不使用Lua
Map<String, Double> map = Maps.newHashMap();
Map<String, String> hash = Maps.newHashMap();
for (OrderMessage message : messages) {
// 故意把score设计成30分钟前
map.put(message.getOrderId(), Double.valueOf(String.valueOf(System.currentTimeMillis() - 30 * 60 * 1000)));
hash.put(message.getOrderId(), JSON.toJSONString(message));
}
jedis.zadd("ORDER_QUEUE", map);
jedis.hmset("ORDER_DETAIL_QUEUE", hash);
}
}
}

输出结果如下:

2019-08-21 22:45:59.518  INFO 33000 --- [ryBean_Worker-1] club.throwable.OrderMessageConsumer      : 订单消息处理定时任务开始执行......
2019-08-21 22:45:59.525 INFO 33000 --- [onsumerWorker-4] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_91, amount=91, userId=91, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:45:59.525 INFO 33000 --- [onsumerWorker-2] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_95, amount=95, userId=95, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:45:59.525 INFO 33000 --- [onsumerWorker-1] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_97, amount=97, userId=97, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:45:59.525 INFO 33000 --- [onsumerWorker-0] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_99, amount=99, userId=99, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:45:59.525 INFO 33000 --- [onsumerWorker-3] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_93, amount=93, userId=93, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:45:59.539 INFO 33000 --- [onsumerWorker-2] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_94, amount=94, userId=94, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:45:59.539 INFO 33000 --- [onsumerWorker-1] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_96, amount=96, userId=96, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:45:59.539 INFO 33000 --- [onsumerWorker-3] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_92, amount=92, userId=92, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:45:59.539 INFO 33000 --- [onsumerWorker-0] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_98, amount=98, userId=98, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:45:59.539 INFO 33000 --- [onsumerWorker-4] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_90, amount=90, userId=90, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:45:59.540 INFO 33000 --- [ryBean_Worker-1] club.throwable.OrderMessageConsumer : 订单消息处理定时任务执行完毕,耗时:22 ms......
2019-08-21 22:46:04.515 INFO 33000 --- [ryBean_Worker-2] club.throwable.OrderMessageConsumer : 订单消息处理定时任务开始执行......
2019-08-21 22:46:04.516 INFO 33000 --- [onsumerWorker-5] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_89, amount=89, userId=89, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:46:04.516 INFO 33000 --- [onsumerWorker-6] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_87, amount=87, userId=87, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:46:04.516 INFO 33000 --- [onsumerWorker-7] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_85, amount=85, userId=85, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:46:04.516 INFO 33000 --- [onsumerWorker-5] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_88, amount=88, userId=88, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:46:04.516 INFO 33000 --- [onsumerWorker-2] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_83, amount=83, userId=83, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:46:04.516 INFO 33000 --- [onsumerWorker-1] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_81, amount=81, userId=81, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:46:04.516 INFO 33000 --- [onsumerWorker-6] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_86, amount=86, userId=86, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:46:04.516 INFO 33000 --- [onsumerWorker-2] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_82, amount=82, userId=82, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:46:04.516 INFO 33000 --- [onsumerWorker-7] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_84, amount=84, userId=84, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:46:04.516 INFO 33000 --- [onsumerWorker-1] club.throwable.OrderMessageConsumer : 处理订单信息,内容:OrderMessage(orderId=ORDER_ID_80, amount=80, userId=80, timestamp=2019-08-21 22:45:59.475)
2019-08-21 22:46:04.516 INFO 33000 --- [ryBean_Worker-2] club.throwable.OrderMessageConsumer : 订单消息处理定时任务执行完毕,耗时:1 ms......
......

首次执行的时候涉及到一些组件的初始化,会比较慢,后面看到由于我们只是简单打印订单信息,所以定时任务执行比较快。如果在不调整当前架构的情况下,生产中需要注意:

  • 切换JobStoreJDBC模式,Quartz官方有完整教程,或者看笔者之前翻译的Quartz文档。
  • 需要监控或者收集任务的执行状态,添加预警等等。

这里其实有一个性能隐患,命令ZREVRANGEBYSCORE的时间复杂度可以视为为O(N)N是集合的元素个数,由于这里把所有的订单信息都放进了同一个Sorted Set(ORDER_QUEUE)中,所以在一直有新增数据的时候,dequeue脚本的时间复杂度一直比较高,后续订单量升高之后会此处一定会成为性能瓶颈,后面会给出解决的方案。

小结

这篇文章主要从一个实际生产案例的仿真例子入手,分析了当前延时任务的一些实现方案,还基于RedisQuartz给出了一个完整的示例。当前的示例只是处于可运行的状态,有些问题尚未解决。下一篇文章会着眼于解决两个方面的问题:

  1. 分片。
  2. 监控。

还有一点,架构是基于业务形态演进出来的,很多东西需要结合场景进行方案设计和改进,思路仅供参考,切勿照搬代码

附件

  • Markdown和PPT原件:

(本文完 c-5-d e-a-20190821 顺便开通了RSS插件,见主页的图标,欢迎订阅 r-a-20190904)

文章作者: throwable
文章链接: http://www.throwable.club/2019/08/21/redis-delay-task-first/
版权声明: 本博客所有文章除特别声明外,均采用 CC BY-NC-SA 4.0 许可协议。转载请注明来自 Throwable
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