WorkerService (Apache ZooKeeper - Server 3.9.1 API)

java.lang.Object
- org.apache.zookeeper.server.WorkerService

```
public class WorkerService
extends Object
```
WorkerService is a worker thread pool for running tasks and is implemented using one or more ExecutorServices. A WorkerService can support assignable threads, which it does by creating N separate single thread ExecutorServices, or non-assignable threads, which it does by creating a single N-thread ExecutorService. - NIOServerCnxnFactory uses a non-assignable WorkerService because the socket IO requests are order independent and allowing the ExecutorService to handle thread assignment gives optimal performance. - CommitProcessor uses an assignable WorkerService because requests for a given session must be processed in order. ExecutorService provides queue management and thread restarting, so it's useful even with a single thread.

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`static class`	`WorkerService.WorkRequest`	Callers should implement a class extending WorkRequest in order to schedule work with the service.

Constructor Summary

Constructors
Constructor Description

WorkerService(String name, int numThreads, boolean useAssignableThreads)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`join(long shutdownTimeoutMS)`
`void`	`schedule(WorkerService.WorkRequest workRequest)`	Schedule work to be done.
`void`	`schedule(WorkerService.WorkRequest workRequest, long id)`	Schedule work to be done by the thread assigned to this id.
`void`	`start()`
`void`	`stop()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - WorkerService
```
public WorkerService(String name,
                     int numThreads,
                     boolean useAssignableThreads)
```
    Parameters:
    
    name - worker threads are named <name>Thread-##
    
    numThreads - number of worker threads (0 - N) If 0, scheduled work is run immediately by the calling thread.
    
    useAssignableThreads - whether the worker threads should be individually assignable or not
- Method Detail
  - schedule
```
public void schedule(WorkerService.WorkRequest workRequest)
```
    Schedule work to be done. If a worker thread pool is not being used, work is done directly by this thread. This schedule API is for use with non-assignable WorkerServices. For assignable WorkerServices, will always run on the first thread.
  - schedule
```
public void schedule(WorkerService.WorkRequest workRequest,
                     long id)
```
    Schedule work to be done by the thread assigned to this id. Thread assignment is a single mod operation on the number of threads. If a worker thread pool is not being used, work is done directly by this thread.
  - start
```
public void start()
```
  - stop
```
public void stop()
```
  - join
```
public void join(long shutdownTimeoutMS)
```