SpringBoot同时使用Caffeine与Simple缓存触发异常问题咨询

作为SpringBoot新手，因业务需求需同时实现Caffeine缓存与Simple缓存。单独使用任意一种缓存时编译及运行均正常，但同时使用（无论同一类或不同类中）会触发异常，咨询是否可以同时使用这两种缓存机制。

异常信息 #

Oct 10, 2023 9:40:06 PM org.apache.catalina.loader.WebappClassLoaderBase clearReferencesThreads
WARNING: The web application [ROOT] appears to have started a thread named [cluster-ClusterId{value='6525775bd54ff65387d86e72', description='null'}-localhost:27017] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
 java.net.SocketInputStream.socketRead0(Native Method)
 java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
 java.net.SocketInputStream.read(SocketInputStream.java:171)
 java.net.SocketInputStream.read(SocketInputStream.java:141)
 com.mongodb.internal.connection.SocketStream.read(SocketStream.java:109)
 com.mongodb.internal.connection.SocketStream.read(SocketStream.java:131)
 com.mongodb.internal.connection.InternalStreamConnection.receiveResponseBuffers(InternalStreamConnection.java:647)
 com.mongodb.internal.connection.InternalStreamConnection.receiveMessageWithAdditionalTimeout(InternalStreamConnection.java:512)
 com.mongodb.internal.connection.InternalStreamConnection.receiveCommandMessageResponse(InternalStreamConnection.java:355)
 com.mongodb.internal.connection.InternalStreamConnection.receive(InternalStreamConnection.java:315)
 com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.lookupServerDescription(DefaultServerMonitor.java:215)
 com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:144)
 java.lang.Thread.run(Thread.java:750)
Oct 10, 2023 9:40:06 PM org.apache.catalina.loader.WebappClassLoaderBase clearReferencesThreads
WARNING: The web application [ROOT] appears to have started a thread named [cluster-rtt-ClusterId{value='6525775bd54ff65387d86e72', description='null'}-localhost:27017] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
 java.lang.Thread.sleep(Native Method)
 com.mongodb.internal.connection.DefaultServerMonitor.waitForNext(DefaultServerMonitor.java:435)
 com.mongodb.internal.connection.DefaultServerMonitor.access$1300(DefaultServerMonitor.java:57)
 com.mongodb.internal.connection.DefaultServerMonitor$RoundTripTimeRunnable.run(DefaultServerMonitor.java:409)
 java.lang.Thread.run(Thread.java:750)

Java配置类 #

@Configuration
@EnableCaching
public class CacheConfig {


    @Bean
    public CacheManager caffeineCacheManager() {
        CaffeineCacheManager cacheManager = new CaffeineCacheManager();
        cacheManager.setCacheNames(Arrays.asList("task1"));
        cacheManager.setCaffeine(caffeineCacheBuilder());
        return cacheManager;
    }

    Caffeine<Object, Object> caffeineCacheBuilder() {
        return Caffeine.newBuilder()
                .expireAfterWrite(30, TimeUnit.DAYS) // Set TTL for 30 Days
                .maximumSize(5000); // Set maximum size to 5000 entries
    }

    @Bean
    public CacheManager cacheManager() {
        SimpleCacheManager cacheManager = new SimpleCacheManager();
        cacheManager.setCaches(Arrays.asList(new ConcurrentMapCache("task2")));
        return cacheManager;
    }

}

Maven依赖 #

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-cache</artifactId>
</dependency>
<dependency>
    <groupId>com.github.ben-manes.caffeine</groupId>
    <artifactId>caffeine</artifactId>
    <version>2.7.0</version>
</dependency>

注：仅同时使用两种缓存机制时会触发异常，单独使用任意一种均运行正常。

问题分析与解决方案 #

Spring Boot支持同时使用多种缓存机制，你遇到的异常本质是容器中存在多个CacheManager Bean时，Spring无法确定默认使用哪一个，导致缓存初始化逻辑异常，间接引发MongoDB线程未正常关闭的问题。

修复步骤： #

1. 指定默认缓存管理器
   在其中一个CacheManager的Bean方法上添加@Primary注解，标记为默认使用的缓存管理器。比如将Caffeine缓存设为默认：

   @Bean
   @Primary
   public CacheManager caffeineCacheManager() {
       // 原有代码不变
   }
   

2. 使用指定缓存管理器
   在业务代码中使用缓存时，通过cacheManager属性指定要使用的缓存管理器Bean名称：

   // 使用Caffeine缓存
   @Cacheable(value = "task1", cacheManager = "caffeineCacheManager")
   public YourObject getTask1Data() {
       // 业务逻辑
   }
   
   // 使用Simple缓存
   @Cacheable(value = "task2", cacheManager = "cacheManager")
   public YourObject getTask2Data() {
       // 业务逻辑
   }
   

3. MongoDB线程泄漏补充检查
   虽然异常由缓存配置冲突引发，但可以额外检查MongoDB连接配置，确保使用Spring Boot自动配置的MongoTemplate，并在应用关闭时正确释放连接池资源。

内容的提问来源于stack exchange，提问作者Harish Mahi