Class NioServerSocketChannelFactory
- All Implemented Interfaces:
ChannelFactory
,ServerChannelFactory
,ServerSocketChannelFactory
,ExternalResourceReleasable
ServerSocketChannelFactory
which creates a server-side NIO-based
ServerSocketChannel
. It utilizes the non-blocking I/O mode which
was introduced with NIO to serve many number of concurrent connections
efficiently.
How threads work
There are two types of threads in a NioServerSocketChannelFactory
;
one is boss thread and the other is worker thread.
Boss threads
Each bound ServerSocketChannel
has its own boss thread.
For example, if you opened two server ports such as 80 and 443, you will
have two boss threads. A boss thread accepts incoming connections until
the port is unbound. Once a connection is accepted successfully, the boss
thread passes the accepted Channel
to one of the worker
threads that the NioServerSocketChannelFactory
manages.
Worker threads
One NioServerSocketChannelFactory
can have one or more worker
threads. A worker thread performs non-blocking read and write for one or
more Channel
s in a non-blocking mode.
Life cycle of threads and graceful shutdown
All threads are acquired from the Executor
s which were specified
when a NioServerSocketChannelFactory
was created. Boss threads are
acquired from the bossExecutor
, and worker threads are acquired from
the workerExecutor
. Therefore, you should make sure the specified
Executor
s are able to lend the sufficient number of threads.
It is the best bet to specify a cached thread pool.
Both boss and worker threads are acquired lazily, and then released when
there's nothing left to process. All the related resources such as
Selector
are also released when the boss and worker threads are
released. Therefore, to shut down a service gracefully, you should do the
following:
- unbind all channels created by the factory,
- close all child channels accepted by the unbound channels, and
(these two steps so far is usually done using
ChannelGroup.close()
) - call
releaseExternalResources()
.
RejectedExecutionException
and the related resources might not be released properly.-
Field Summary
FieldsModifier and TypeFieldDescriptionprivate final BossPool<NioServerBoss>
private boolean
private final NioServerSocketPipelineSink
private final WorkerPool<NioWorker>
-
Constructor Summary
ConstructorsConstructorDescriptionCreate a newNioServerSocketChannelFactory
usingExecutors.newCachedThreadPool()
for the boss and worker.NioServerSocketChannelFactory
(Executor bossExecutor, int bossCount, Executor workerExecutor, int workerCount) Create a new instance.NioServerSocketChannelFactory
(Executor bossExecutor, int bossCount, WorkerPool<NioWorker> workerPool) Create a new instance.NioServerSocketChannelFactory
(Executor bossExecutor, Executor workerExecutor) Creates a new instance.NioServerSocketChannelFactory
(Executor bossExecutor, Executor workerExecutor, int workerCount) Creates a new instance.NioServerSocketChannelFactory
(Executor bossExecutor, WorkerPool<NioWorker> workerPool) Creates a new instance.NioServerSocketChannelFactory
(BossPool<NioServerBoss> bossPool, WorkerPool<NioWorker> workerPool) Create a new instance. -
Method Summary
Modifier and TypeMethodDescriptionprivate static int
getMaxThreads
(Executor executor) Returns number of max threads for theNioWorkerPool
to use.newChannel
(ChannelPipeline pipeline) void
Releases the external resources that this factory depends on to function.private void
void
shutdown()
Shudown the ChannelFactory and all the resource it created internal.
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Field Details
-
workerPool
-
sink
-
bossPool
-
releasePools
private boolean releasePools
-
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Constructor Details
-
NioServerSocketChannelFactory
public NioServerSocketChannelFactory()Create a newNioServerSocketChannelFactory
usingExecutors.newCachedThreadPool()
for the boss and worker. SeeNioServerSocketChannelFactory(Executor, Executor)
-
NioServerSocketChannelFactory
Creates a new instance. Calling this constructor is same with callingNioServerSocketChannelFactory(Executor, Executor, int)
with the worker executor passed intogetMaxThreads(Executor)
. -
NioServerSocketChannelFactory
public NioServerSocketChannelFactory(Executor bossExecutor, Executor workerExecutor, int workerCount) Creates a new instance. -
NioServerSocketChannelFactory
public NioServerSocketChannelFactory(Executor bossExecutor, int bossCount, Executor workerExecutor, int workerCount) Create a new instance. -
NioServerSocketChannelFactory
Creates a new instance.- Parameters:
bossExecutor
- theExecutor
which will execute the boss threadsworkerPool
- theWorkerPool
which will be used to obtain theNioWorker
that execute the I/O worker threads
-
NioServerSocketChannelFactory
public NioServerSocketChannelFactory(Executor bossExecutor, int bossCount, WorkerPool<NioWorker> workerPool) Create a new instance.- Parameters:
bossExecutor
- theExecutor
which will execute the boss threadsbossCount
- the number of boss threadsworkerPool
- theWorkerPool
which will be used to obtain theNioWorker
that execute the I/O worker threads
-
NioServerSocketChannelFactory
public NioServerSocketChannelFactory(BossPool<NioServerBoss> bossPool, WorkerPool<NioWorker> workerPool) Create a new instance.- Parameters:
bossPool
- theBossPool
which will be used to obtain theNioServerBoss
that execute the I/O for accept new connectionsworkerPool
- theWorkerPool
which will be used to obtain theNioWorker
that execute the I/O worker threads
-
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Method Details
-
newChannel
Description copied from interface:ChannelFactory
- Specified by:
newChannel
in interfaceChannelFactory
- Specified by:
newChannel
in interfaceServerChannelFactory
- Specified by:
newChannel
in interfaceServerSocketChannelFactory
- Parameters:
pipeline
- theChannelPipeline
which is going to be attached to the newChannel
- Returns:
- the newly open channel
-
shutdown
public void shutdown()Description copied from interface:ChannelFactory
Shudown the ChannelFactory and all the resource it created internal.- Specified by:
shutdown
in interfaceChannelFactory
-
releaseExternalResources
public void releaseExternalResources()Description copied from interface:ChannelFactory
Releases the external resources that this factory depends on to function. An external resource is a resource that this factory didn't create by itself. For example,Executor
s that you specified in the factory constructor are external resources. You can call this method to release all external resources conveniently when the resources are not used by this factory or any other part of your application. An unexpected behavior will be resulted in if the resources are released when there's an open channel which is managed by this factory. This will also callChannelFactory.shutdown()
before do any action- Specified by:
releaseExternalResources
in interfaceChannelFactory
- Specified by:
releaseExternalResources
in interfaceExternalResourceReleasable
-
releasePools
private void releasePools() -
getMaxThreads
Returns number of max threads for theNioWorkerPool
to use. If the *Executor
is aThreadPoolExecutor
, check its maximum * pool size and return either it's maximum orSelectorUtil.DEFAULT_IO_THREADS
, whichever is lower. Note thatSelectorUtil.DEFAULT_IO_THREADS
is 2 * the number of available processors in the machine. The number of available processors is obtained byRuntime.availableProcessors()
.- Parameters:
executor
- theExecutor
which will execute the I/O worker threads- Returns:
- number of maximum threads the NioWorkerPool should use
-