Ehcache开启JMX支持

小鱼儿 2022-06-07 03:09 171阅读 0赞

Ehcache提供了基于JMX的监控支持，支持对以下几类信息的监控。  
\* CacheManager  
\* Cache  
\* CacheConfiguration  
\* CacheStatistics

按照JMX的规范，为了支持对这几类信息的监控支持，Ehcache分别为它们建立了对应的MBean接口，这些接口都定义在net.sf.ehcache.management包中，分别是CacheManagerMBean、CacheMBean、CacheConfigurationMBean和CacheStatisticsMBean。按照JMX的规范，JMX监控页面只能查看MBean中定义的属性（get方法）和执行MBean接口中定义的操作（方法）。比方说CacheManagerMBean的定义如下，它能看到的属性就是status、name、cacheNames、caches、transactionCommittedCount、transactionRolledBackCount和transactionTimedOutCount。能进行的操作是shutdown()和clearAll()。

public interface CacheManagerMBean { 
    
        /** * Gets the status attribute of the Ehcache * * @return The status value, as a String from the Status enum class */
        String getStatus();
    
        /** * Gets the name of the cache manager * * @return The name of the CacheManager */
        String getName();
    
         /** * Shuts down the CacheManager. * <p/> * If the shutdown occurs on the singleton, then the singleton is removed, so that if a singleton access method * is called, a new singleton will be created. */
        void shutdown();
    
    
        /** * Clears the contents of all caches in the CacheManager, but without * removing any caches. * <p/> * This method is not synchronized. It only guarantees to clear those elements in a cache * at the time that the {@link net.sf.ehcache.Ehcache#removeAll()} mehod on each cache is called. */
        void clearAll();
    
    
        /** * Returns a JMX Cache bean * */
        Cache getCache(String name);
    
    
        /** * Gets the cache names managed by the CacheManager */
        String[] getCacheNames() throws IllegalStateException;
    
        /** * Gets a list of caches in this CacheManager * @return a list of JMX Cache objects */
        List getCaches();
    
        /** * Get the committed transactions count * @return the committed transactions count */
        long getTransactionCommittedCount();
    
        /** * Get the rolled back transactions count * @return the rolled back transactions count */
        long getTransactionRolledBackCount();
    
        /** * Get the timed out transactions count. Note that only transactions which failed to * commit due to a timeout are taken into account * @return the timed out transactions count */
        long getTransactionTimedOutCount();
    
    }

注册这些MBean，Ehcache提供了一个工具类，ManagementService，可以通过它的registerMBeans方法进行注册，该方法定义如下，后面对应的4个boolean类型的参数，表示是否需要注册对应的MBean，依次表示CacheManager、Cache、CacheConfiguration和CacheStatistics。该工具方法最终会生成一个ManagementService实例，ManagementService实现了CacheManagerEventListener接口，所以它能感知到Cache的变化。

public static void registerMBeans(
        net.sf.ehcache.CacheManager cacheManager,
        MBeanServer mBeanServer,
        boolean registerCacheManager,
        boolean registerCaches,
        boolean registerCacheConfigurations,
        boolean registerCacheStatistics) throws CacheException {
    //...
    }

以下是一个注册Ehcache对应的MBean的示例代码：

CacheManager cacheManager = new CacheManager();
    String cacheName = "test";
    Ehcache cache = cacheManager.addCacheIfAbsent(cacheName);
    cache.put(new Element("key is a object", "value is a object"));
    
    MBeanServer mBeanServer = ManagementFactory.getPlatformMBeanServer();
    ManagementService.registerMBeans(cacheManager, mBeanServer, true, true, true, true);

注册之后我们就可以通过jconsole的JMX界面看到对应的MBean的信息了。

![JMX][]

Ehcache相关的MBean的objectName的命名规范如下：  
\* CacheManager - `“net.sf.ehcache:type=CacheManager,name=<CacheManager>”`  
\* Cache - `“net.sf.ehcache:type=Cache,CacheManager=<cacheManagerName>,name=<cacheName>”`  
\* CacheConfiguration - `“net.sf.ehcache:type=CacheConfiguration,CacheManager=<cacheManagerName>,name=<cacheName>”`  
\* CacheStatistics - `“net.sf.ehcache:type=CacheStatistics,CacheManager=<cacheManagerName>,name=<cacheName>”`

**参考文档**  
[http://www.ehcache.org/documentation/2.7/operations/jmx.html][http_www.ehcache.org_documentation_2.7_operations_jmx.html]

（本文是基于Ehcache2.10.4所写，由Elim写于2017年10月8日）

[JMX]: /images/20220607/efed745dbab14b3f89486c3ddcb3f5f0.png
[http_www.ehcache.org_documentation_2.7_operations_jmx.html]: http://www.ehcache.org/documentation/2.7/operations/jmx.html