Advanced thread Development (thread pool, resource blocking, and queue)

From: http://my.oschina.net/dxf/blog/239

After jdk1.5, the Java. util. Concurrent package is provided, which can implement the thread pool. You can regard the thread as a common object, which is responsible for scheduling and execution.

Including two types of thread pools

Fixed Thread Pool

Variable Thread Pool

Delay Thread Pool

 

Fixed Thread Pool

Public static executorservice newfixedthreadpool (INT nthreads) multi-task

Public static executorservice newsinglethreadpool () single task

Executorservice Method

Excute (runnablecommand );

Shutdown ();

Usage:

Mytask MT1 = new mytask ("T1"); // a thread object instance

Executorservice threadpool = executors. newfixedthreadpool (2 );

Threadpool. excute (MT1 );

 

Variable Thread Pool

Public static executorservice newcachedthreadpool ()

 

Delay thread pool for scheduled tasks

Public static scheduledexecutorservice newscheduledthreadpool (INT poolsize)

Instead of using the excute method, it uses the schedule method.

Public schedualedfuture schedule (runnable command, long delay, timeunit Unit );

 

Thread Pool with return value

The callable interface works with the future interface, which is used to accept the returned value.

The callable interface works the same as the runnable interface, but it is a call interface method. This method also has a return value.

Class mycallableimpl implements callable

{

Public object call ()

{

}

}

Use

Executorservice threadpool = executors. newsinglethreadexector ();

Future F = threadpool. Submit (New mycallableimpl ();

 

Resource Blocking

We know that the syncnized method can block resources of a piece of code. In fact, there are many other methods. Here we will summarize them.

1: Synchronized

2: Volatile

3: implement the reentrantlock class of the lock interface. The methods include lock (), unlock (), and trylock (). Be sure to try ...... Finally to prevent deadlocks

4: The readwritelock interface implements the reentrantreadwritelock class. The methods are readlock and writelock. The method is generally the same as the lock interface, but its efficiency is high. Also avoid deadlocks

5: semaphores semaphore class. semaphores are used to allocate resources, but they also have the lock feature. For example, the connection pool can be used without the explosion of the connection pool, main Methods: acquire (), acquire (int n), tryacquire (), getqueuelength (), release ()

6: Atomic objects. After jdk15, some basic types can be defined as atomic objects for single-thread operations to simplify operations. Java. util. Concurrent. Atomic, which serves basically the same variable volatile

7: Barrier, cyclicbarrier class, to synchronize threads to the same point

 

Queue and stack

Java. util. Queue Interface

Public Boolean offer (object); add

Public object poll ();

Peek (); out, but not deleted

Remove (); same as poll

Element (); same as peek

Add (); same as offer

Common implementations: Java. util. shortlist and Java. util. priorityqueue

Blockingqueue Interface

Java. util. Concurrent. blockingqueue

Put (object );

Take (); Out

Blockingdeque Interface

It is a blocking stack interface.

Putfirst (Object O );

Takefirst ();

Putlast ();

Takelast ();