Coherence CE (Community Edition) is a free and open source edition of Oracle Coherence, first and market-leading in-memory data grid

Coherence CE (Community Edition) is a free and open source edition of Oracle Coherence, first and market-leading in-memory data grid. It has been used by hundreds of customers across many industries to power some of the mission critical systems you use every day. Coherence clusters can easily scale to hundreds of members (JVMs), all of which can both store and process the data. It can optionally persist data to disk (either local or shared), which prevents data loss even in the case of complete cluster outage.

Coherence is fast. Like, sub-millisecond fast. Each member of the cluster is aware of where each piece of data resides and can access it using a single network call. There are no connections to acquire or release, and no distributed transactions to commit or roll back.