ehcache usage statistics

Since ehcache-1.2 was released a few days ago, there have been plenty of people taking a peek at it.

It is sort of fun to look at the web traffic and downloads of ehcache since the project inception in 2003. The first jump happened in December 2004 with the release of ehcache-1.1. There was steady growth after that and then another jump with the release of 1.2. To date there have been direct 31,796 downloads from the SourceForge site.

The thing that is a little harder to measure is how many people’s machines it is sitting on. Ehcache is included with the very popular Hibernate and Spring frameworks, along with lots of other things. That ease of redistribution is a killer advantage of open source.

Web Traffic


ehcache-1.2 released – distributed caching, listeners and more

After 10 months of development, ehcache-1.2 has been released.

Thanks to all the developers who contributed to the release through feature requests, bug reports and patches during the beta program.

The 1.2 release of ehcache has many new features including:

  • Flexible, extensible, high performance distributed caching. The default implementation supports cache discovery via multicast or manual configuration. Updates are delivered either asynchronously or synchronously via custom RMI connections. Additional discovery or delivery schemes can be plugged in by third parties.
  • New FIFO and LFU caching policies in addition to the standard LRU.
  • Introduced CacheManagerEventListener and CacheEventListener interfaces and default implementations.
  • Multiple CacheManagers per virtual machine.
  • Programmatic flushing of application state to persistent caches
  • Significant (up to 7 fold) DiskStore performance increases.
  • API for Objects in addition to Serializable. Non-serializable Objects can use all parts of ehcache except for DiskStore and replication. Two new methods on Element: getObjectValue and getKeyValue are the only API differences between the Serializable and Object APIs.
  • Backward Compatibility with ehcache-1.1. All users of ehcache-1.1 should be able to upgrade to ehcache-1.2.
  • Tested with Hibernate2.1.8 and Hibernate3.1.3, which can utilise all of the new features except for Object API and multiple session factories each using a different ehcache CacheManager. A new net.sf.ehcache.hibernate.EhCacheProvider makes those additional features available to Hibernate-3.1.3. A version of the new provider should make it into the Hibernate3.2 release.
  • Tested with ehcache-constructs.
  • Apache 2.0 license


ehcache 1.2: I can almost taste it

Well another weekend spent on ehcache.

Added a long requested feature to accept keys and values that do not implement Serializable. This makes ehcache suitable for a lot more purposes. I was always afraid of the subtleties involved with NonSerializable Elements getting into the system and then not being able to be persisted to DiskStores or replicated. But it is just a matter of gracefully degrading and logging warnings. It was quite simple really.

Also fixed some minor bugs to do with rare edge conditions. This makes ehcache more robust.

There is only one old bug to fix. No patches to process. And pretty much all the feature requests that are going to get into this release are in.

So what is stopping me from releasing 1.2? I am getting desperate for reasons not to release it. The problem with open source projects are either no one uses them and you can change them as often as you like, or they are widely used like ehcache and you become ultra cautious.

I probably want to do the following before I release:

– fix that last bug
– I promised the Hibernate guys a new ehcache plugin.
– more torture tests for replication.

Perhaps next weekend…

The Place to Be

For a couple of weeks now I have been an ex-ThoughtWorker rather than a ThoughtWorker. It turns out there are a few of us, and Adwale Oshineye has thoughtfully created an alumni aggregator at Being a consultant can require a big travel commitment, so for a lot of people consulting has a limited lifespan.

Now that I am no longer aggregated on the main page of blogs.thoughtworks, I feel I can make the occasional wry comment. Also, TW Australia is headquartered in Melbourne, Victoria, upon which I am about to play a prank.

I am been doing a lot of driving lately down to my 40 ha (100 acre) farm. I notice a lot of Victorians on the roads here in Queensland, a good 1700km from home. As I drive I cannot help notice the wording on the number plate. Some say “On the move” and some say “The place to be”. In fact the plate has changed from “On the move” to the “place to be”. Let me repeat that: on the move to the place to be! How unfortunate when you see those number plates outside of Victoria.