Thread Pool

from: Executor Framework in Java

Executor

This interface has a single method (execute) to execute a Runnable task.

```java
public interface Executor {
    void execute(Runnable command);
}
```

ExecutorService

It supplements base class (Executor) by adding more methods to control life cycle.

```java
 void shutdown();
 List<Runnable> shutdownNow();

 ```