Chapter 18. Distributed Execution
Red Hat JBoss Data Grid provides distributed execution through a standard JDK
ExecutorService interface. Tasks submitted for execution are executed on an entire cluster of JBoss Data Grid nodes, rather than being executed in a local JVM.
JBoss Data Grid's distributed task executors can use data from JBoss Data Grid cache nodes as input for execution tasks. As a result, there is no need to configure the cache store for intermediate or final results. As input data in JBoss Data Grid is already load balanced, tasks are also automatically balanced, therefore there is no need to explicitly assign tasks to specific nodes.
In JBoss Data Grid's distributed execution framework:
- Each
DistributedExecutorServiceis bound to a single cache. Tasks submitted have access to key/value pairs from that particular cache if the task submitted is an instance ofDistributedCallable. - Every
Callable,Runnable, and/orDistributedCallablesubmitted must be eitherSerializableorExternalizable, in order to prevent task migration to other nodes each time one of these tasks is performed. The value returned from aCallablemust also beSerializableorExternalizable.
18.1. DistributedCallable API
The
DistributedCallable interface is a subtype of the existing Callable from java.util.concurrent.package, and can be executed in a remote JVM and receive input from Red Hat JBoss Data Grid. The DistributedCallable interface is used to facilitate tasks that require access to JBoss Data Grid cache data.
When using the
DistributedCallable API to execute a task, the task's main algorithm remains unchanged, however the input source is changed.
Users who have already implemented
Callable interface to describe task units must extend DistributedCallable and use keys from JBoss Data Grid execution environment as input for the task. For example:
public interface DistributedCallable<K, V, T> extends Callable<T> {
/**
* Invoked by execution environment after DistributedCallable
* has been migrated for execution to a specific Infinispan node.
*
* @param cache
* cache whose keys are used as input data for this
* DistributedCallable task
* @param inputKeys
* keys used as input for this DistributedCallable task
*/
public void setEnvironment(Cache<K, V> cache, Set<K> inputKeys);
}
