Package org.apache.hadoop.util

Class SemaphoredDelegatingExecutor

java.lang.Object

org.apache.hadoop.thirdparty.com.google.common.collect.ForwardingObject

org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

org.apache.hadoop.util.SemaphoredDelegatingExecutor

All Implemented Interfaces:

Executor, ExecutorService

Direct Known Subclasses:

BlockingThreadPoolExecutorService

@Private
public class SemaphoredDelegatingExecutor
extends org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

This ExecutorService blocks the submission of new tasks when its queue is already full by using a semaphore. Task submissions require permits, task completions release permits.

This is a refactoring of BlockingThreadPoolExecutorService; that code contains the thread pool logic, whereas this isolates the semaphore and submit logic for use with other thread pools and delegation models.

This is inspired by this s4 threadpool

Constructor Summary

Constructors

Constructor	Description
SemaphoredDelegatingExecutor(ExecutorService executorDelegatee, int permitCount, boolean fair)	Instantiate without collecting executor aquisition duration information.
SemaphoredDelegatingExecutor(ExecutorService executorDelegatee, int permitCount, boolean fair, DurationTrackerFactory trackerFactory)	Instantiate.

Method Summary

Modifier and Type	Method	Description
protected ExecutorService	delegate()
void	execute(Runnable command)
int	getAvailablePermits()	Get the number of permits available; guaranteed to be 0 <= availablePermits <= size.
int	getPermitCount()	Total number of permits.
int	getWaitingCount()	Get the number of threads waiting to acquire a permit.
<T> List<Future<T>>	invokeAll(Collection<? extends Callable<T>> tasks)
<T> List<Future<T>>	invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
<T> T	invokeAny(Collection<? extends Callable<T>> tasks)
<T> T	invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
Future<?>	submit(Runnable task)
<T> Future<T>	submit(Runnable task, T result)
<T> Future<T>	submit(Callable<T> task)
String	toString()

Methods inherited from class org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

awaitTermination, isShutdown, isTerminated, shutdown, shutdownNow

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

SemaphoredDelegatingExecutor

public SemaphoredDelegatingExecutor(ExecutorService executorDelegatee,
 int permitCount,
 boolean fair,
 DurationTrackerFactory trackerFactory)

Instantiate.

Parameters:

executorDelegatee - Executor to delegate to

permitCount - number of permits into the queue permitted

fair - should the semaphore be "fair"

trackerFactory - duration tracker factory.

SemaphoredDelegatingExecutor

public SemaphoredDelegatingExecutor(ExecutorService executorDelegatee,
 int permitCount,
 boolean fair)

Instantiate without collecting executor aquisition duration information.

Parameters:

executorDelegatee - Executor to delegate to

permitCount - number of permits into the queue permitted

fair - should the semaphore be "fair"

Method Details

delegate

protected ExecutorService delegate()

Specified by:

delegate in class org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

invokeAll

public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
                              throws InterruptedException

Specified by:

invokeAll in interface ExecutorService

Overrides:

invokeAll in class org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

Throws:

InterruptedException

invokeAll

public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
 long timeout,
 TimeUnit unit)
                              throws InterruptedException

Specified by:

invokeAll in interface ExecutorService

Overrides:

invokeAll in class org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

Throws:

InterruptedException

invokeAny

public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
                throws InterruptedException,
ExecutionException

Specified by:

invokeAny in interface ExecutorService

Overrides:

invokeAny in class org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

Throws:

InterruptedException

ExecutionException

invokeAny

public <T> T invokeAny(Collection<? extends Callable<T>> tasks,
 long timeout,
 TimeUnit unit)
                throws InterruptedException,
ExecutionException,
TimeoutException

Specified by:

invokeAny in interface ExecutorService

Overrides:

invokeAny in class org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

Throws:

InterruptedException

ExecutionException

TimeoutException

submit

public <T> Future<T> submit(Callable<T> task)

Specified by:

submit in interface ExecutorService

Overrides:

submit in class org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

submit

public <T> Future<T> submit(Runnable task,
 T result)

Specified by:

submit in interface ExecutorService

Overrides:

submit in class org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

submit

public Future<?> submit(Runnable task)

Specified by:

submit in interface ExecutorService

Overrides:

submit in class org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

execute

public void execute(Runnable command)

Specified by:

execute in interface Executor

Overrides:

execute in class org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ForwardingExecutorService

getAvailablePermits

public int getAvailablePermits()

Get the number of permits available; guaranteed to be 0 <= availablePermits <= size.

Returns:

the number of permits available at the time of invocation.

getWaitingCount

public int getWaitingCount()

Get the number of threads waiting to acquire a permit.

Returns:

snapshot of the length of the queue of blocked threads.

getPermitCount

public int getPermitCount()

Total number of permits.

Returns:

the number of permits as set in the constructor

toString

public String toString()

Overrides:

toString in class org.apache.hadoop.thirdparty.com.google.common.collect.ForwardingObject