什么是“并行”的“任务”(What is the “task” in Storm parallelism)

 我正在尝试学习叽叽t witter的风暴，遵循伟大的文章“ 了解风暴拓扑的并行性 ” 
 
 但是，我对“任务”的概念有些困惑。 任务是组件的运行实例（spout还是螺栓）？ 执行者有多个任务实际上是说执行者多次执行相同的组件，我是否正确？ 
 
 此外，在一般的并行性意义上，Storm将为一个喷口或螺栓生成一个专用的线程（执行器），但是由具有多个任务的执行器（线程）对并行性的贡献是什么？ 我认为在一个线程中有多个任务，因为一个线程顺序执行，只能使线程成为一种“缓存”资源，避免为下一个任务运行产生新的线程。 我对么？ 
 
 我可以在花更多的时间调查之后，自己清理这些混乱，但是你知道我们都喜欢stackoverflow ;-) 
 
 提前致谢。 

I'm trying to learn twitter storm by following the great article "Understanding the parallelism of a Storm topology"
 
However I'm a bit confused by the concept of "task". Is a task an running instance of the component(spout or bolt) ? A executor having multiple tasks actually is saying the same component is executed for multiple times by the executor, am I correct ?
 
Moreover in a general parallelism sense, Storm will spawn a dedicated thread(executor) for a spout or bolt, but what is contributed to the parallelism by an executor(thread) having multiple tasks ? I think having multiple tasks in a thread, since a thread executes sequentially, only make the thread a kind of "cached" resource, which avoids spawning new thread for next task run. Am I correct? 
 
I may clear those confusion by myself after taking more time to investigate, but you know, we both love stackoverflow ;-)
 
Thanks in advance.

原文：https://stackoverflow.com/questions/17257448