Why is ehcache faster than memcache?

Question

Directly quoting from ehcache's website [source]:

The idea here is that your caches are set up in a cache hierarchy. Ehcache sits in front and memcacheg behind. Combining the two lets you elegantly work around limitations imposed by Google App Engine. You get the benefits of the speed of Ehcache together with the umlimited size of memcached. Ehcache contains the hooks to easily do this. To update memcached, use a CacheEventListener. To search against memcacheg on a local cache miss, use cache.getWithLoader() together with a CacheLoader for memcacheg.

This seems to imply that using ehcache with memcached would be faster than using memcached alone. Why would ehcache be faster than memcached? The way I see it, both are in memory caches so why the performance difference?

Simply because its strategy is different. GAE memcache implementation has benefits (unlimited size) that make its architecture a bit slower, as it seems to have some network stack included. ehcache avoids this by using only a very small part of the available memory that is dedicated to the app instance. So the access is quicker but limited in space. Having a lot of data to be cached probably will remove the benefits of ehcache as it will call memcache in its own stack. — Sven Schneider

gerry.liang gerry.liang · Accepted Answer · 2013-12-11T06:25:40

Ehcache often runs in the same jvm process with the application,so it does not need serialization and io costs.

When using Ehcache with memcached,some objects are stored in ehcache heap and others are in memcached. so mix ehcahe and memcached will faster than only use memcached.

Runs ehcache and application in the same JVM process is a way to exchange RAM space for time, but you can not put too many data to ehcache because you need to consider replication between servers.

Why is ehcache faster than memcache?

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