在Hibernate中使用分布式 OSCache

OSCache是一个工业级的J2EE缓存实现。

它可以缓存 ：

1 java对象，
2 页面
3 http请求
4 二进制内容：例如PDF文件

等


正文开始 。。。

为了减少与数据库通信来提高应用的性能,我们在Hibernate中使用了分布式缓存：OSCache。

Oscache是得到了广泛使用的开源 Cache 实现（Hibernate中对它提供了支持），它基于更加可靠高效的设计，最重要的是，新版本的OSCache已经支持集群分布式。如果系统需要在部署在集群中，或者需要部署在多机负载均衡模式的环境中来获取更高性能，那么 OSCache将是不二之选。

我们知道为了实现分布式环境下消息的通知,目前两种比较流行的做法是使用：

1 JavaGroups[http: // www.jgroups.org]
2 JMS

这两种方式都在底层实现了广播发布消息。 由于JGroups可以提供可靠的广播通信.所以我们准备采用JGroups。

一、环境说明

1 OSCache: oscache - 2.3 .jar
2 JGroups: 2.2 . 8 ,目前最高版本是 2.2 . 9.1
3 Hibernate: 3.05

二、下面给出 OScache 官方文档对 JavaGroups 使用的说明：

JavaGroups Configuration
Just make sure you have jgroups-all.jar file in your classpath (for a webapp put it in WEB-INF/lib), and add the JavaGroups broadcasting listener to your oscache.properties file like this:

cache.event.listeners=com.opensymphony.oscache.plugins.clustersupport.JavaGroupsBroadcastingListener

In most cases, that's it! OSCache will now broadcast any cache flush events across the LAN. The jgroups-all.jar library is not included with the binary distribution due to its size, however you can obtain it either by downloading the full OSCache distribution, or by visiting the JavaGroups website.

If you want to run more than one OSCache cluster on the same LAN, you will need to use different multicast IP addresses. This allows the caches to exist in separate multicast groups and therefore not interfere with each other. The IP to use can be specified in your oscache.properties file by the cache.cluster.multicast.ip property. The default value is 231.12.21.132, however you can use any class D IP address. Class D address fall in the range 224.0.0.0 through 239.255.255.255.

If you need more control over the multicast configuration (eg setting network timeout or time-to-live values), you can use the cache.cluster.properties configuration property. Use this instead of the cache.cluster.multicast.ip property. The default value is:

UDP(mcast_addr=231.12.21.132;mcast_port=45566;ip_ttl=32;\
mcast_send_buf_size=150000;mcast_recv_buf_size=80000):\
PING(timeout=2000;num_initial_members=3):\
MERGE2(min_interval=5000;max_interval=10000):\
FD_SOCK:VERIFY_SUSPECT(timeout=1500):\
pbcast.NAKACK(gc_lag=50;retransmit_timeout=300,600,1200,2400,4800;max_xmit_size=8192):\
UNICAST(timeout=300,600,1200,2400):\
pbcast.STABLE(desired_avg_gossip=20000):\
FRAG(frag_size=8096;down_thread=false;up_thread=false):\
pbcast.GMS(join_timeout=5000;join_retry_timeout=2000;shun=false;print_local_addr=true)

See the JavaGroups site for more information. In particular, look at the documentation of Channels in the User's Guide.

三、我在应用中使用的 OSCache.properties：

# CACHE IN MEMORY
#
# If you want to disable memory caching, just uncomment this line.
#
# 不使用内存
cache.memory=false

# CACHE KEY
#
# This is the key that will be used to store the cache in the application
# and session scope.
#
# If you want to set the cache key to anything other than the default
# uncomment this line and change the cache.key
#
# cache.key=__oscache_cache

# USE HOST DOMAIN NAME IN KEY
#
# Servers for multiple host domains may wish to add host name info to
# the generation of the key. If this is true, then uncomment the
# following line.
#
# cache.use.host.domain.in.key=true

# CACHE LISTENERS
#
# These hook OSCache events and perform various actions such as logging
# cache hits and misses, or broadcasting to other cache instances across a cluster.
# See the documentation for further information.
#
# cache.event.listeners=com.opensymphony.oscache.plugins.clustersupport.JMSBroadcastingListener, \
# com.opensymphony.oscache.extra.CacheEntryEventListenerImpl, \
# com.opensymphony.oscache.extra.CacheMapAccessEventListenerImpl, \
# com.opensymphony.oscache.extra.ScopeEventListenerImpl

# 使用 JavaGroups 来实现监听广播式缓存
cache.event.listeners=com.opensymphony.oscache.plugins.clustersupport.JavaGroupsBroadcastingListener

# CACHE PERSISTENCE CLASS
#
# Specify the class to use for persistence. If you use the supplied DiskPersistenceListener,
# don't forget to supply the cache.path property to specify the location of the cache
# directory.
#
# If a persistence class is not specified, OSCache will use memory caching only.
#
# 启动硬盘持久化 Cache
cache.persistence.class=com.opensymphony.oscache.plugins.diskpersistence.DiskPersistenceListener

# CACHE OVERFLOW PERSISTENCE
# Use persistent cache in overflow or not. The default value is false, which means
# the persistent cache will be used at all times for every entry. true is the recommended setting.
#
# cache.persistence.overflow.only=true

# CACHE DIRECTORY
#
# This is the directory on disk where caches will be stored by the DiskPersistenceListener.
# it will be created if it doesn't already exist. Remember that OSCache must have
# write permission to this directory.
#
# Note: for Windows machines, this needs \ to be escaped
# ie Windows:
# cache.path=c:\\myapp\\cache
# or *ix:

# 在Linux下的Cache存放路径
cache.path=/data/jsp/boss.21cn.com/bossimpls/cache/bossuud
#
# cache.path=c:\\app\\cache

# CACHE ALGORITHM
#
# Default cache algorithm to use. Note that in order to use an algorithm
# the cache size must also be specified. If the cache size is not specified,
# the cache algorithm will be Unlimited cache.
#

#使用LRU运算算法，把最少使用的Cache剔除出去
cache.algorithm=com.opensymphony.oscache.base.algorithm.LRUCache
# cache.algorithm=com.opensymphony.oscache.base.algorithm.FIFOCache
# cache.algorithm=com.opensymphony.oscache.base.algorithm.UnlimitedCache

# THREAD BLOCKING BEHAVIOR
#
# When a request is made for a stale cache entry, it is possible that another thread is already
# in the process of rebuilding that entry. This setting specifies how OSCache handles the
# subsequent 'non-building' threads. The default behaviour (cache.blocking=false) is to serve
# the old content to subsequent threads until the cache entry has been updated. This provides
# the best performance (at the cost of serving slightly stale data). When blocking is enabled,
# threads will instead block until the new cache entry is ready to be served. Once the new entry
# is put in the cache the blocked threads will be restarted and given the new entry.
# Note that even if blocking is disabled, when there is no stale data available to be served
# threads will block until the data is added to the cache by the thread that is responsible
# for building the data.
#
# cache.blocking=false

# CACHE SIZE
#
# Default cache size in number of items. If a size is specified but not
# an algorithm, the cache algorithm used will be LRUCache.
#

#这个值设得够大了，就是Cache的容量项目个数
cache.capacity=100000000

# CACHE UNLIMITED DISK
# Use unlimited disk cache or not. The default value is false, which means
# the disk cache will be limited in size to the value specified by cache.capacity.
#

#不使用无限硬盘空间
cache.unlimited.disk=false

# JMS CLUSTER PROPERTIES
#
# Configuration properties for JMS clustering. See the clustering documentation
# for more information on these settings.
#
#cache.cluster.jms.topic.factory=java:comp/env/jms/TopicConnectionFactory
#cache.cluster.jms.topic.name=java:comp/env/jms/OSCacheTopic
#cache.cluster.jms.node.name=node1

# JAVAGROUPS CLUSTER PROPERTIES
#
# Configuration properites for the JavaGroups clustering. Only one of these
# should be specified. Default values (as shown below) will be used if niether
# property is set. See the clustering documentation and the JavaGroups project
# (www.javagroups.com) for more information on these settings.
#
cache.cluster.properties=UDP(mcast_addr=231.12.21.132;mcast_port=45566;ip_ttl=32;\
mcast_send_buf_size=150000;mcast_recv_buf_size=80000):\
PING(timeout=2000;num_initial_members=3):\
MERGE2(min_interval=5000;max_interval=10000):\
FD_SOCK:VERIFY_SUSPECT(timeout=1500):\
pbcast.NAKACK(gc_lag=50;retransmit_timeout=300,600,1200,2400,4800;max_xmit_size=8192):\
UNICAST(timeout=300,600,1200,2400):\
pbcast.STABLE(desired_avg_gossip=20000):\
FRAG(frag_size=8096;down_thread=false;up_thread=false):\
pbcast.GMS(join_timeout=5000;join_retry_timeout=2000;shun=false;print_local_addr=true)
cache.cluster.multicast.ip=231.12.21.132