This is a simple example that demonstrates expiration of entries from a region. This can be used to prevent stale entries from lingering in a region. This also allows control over the system resources consumed by any given region.

A region is a collection of entries which are tuples of key and value. When statistics-gathering is enabled, the region maintains access and modification times for each entry. With entry expiration configured, the region will enforce time-to-live limits on entries. When the time since access or modification exceeds the configured duration, the region will take an action to expire the entry. The region can either destroy expired entries in their entirety or invalidate expired entries by removing their values.

This example creates a region where the entries are destroyed after ten seconds without being updated. The example first puts ten random integers into the region. Then the example loops, printing the number of entries in the region, until the region is empty.

This example assumes you have installed Java and Geode.

1. From the geode-examples/expiration directory, build the example and run unit tests.

    $ ../gradlew build
   

2. Next start a locator, start a server, and create a region.

    $ gfsh run --file=scripts/start.gfsh
   

3. Run the example to demonstrate expiration.

    $ ../gradlew run
   

4. Shut down the system.

    $ gfsh run --file=scripts/stop.gfsh