scheduledexecutorservice

First, Scheduledexecutorservice design thoughtScheduledexecutorservice is a timed task class based on thread pool design, where each dispatch task is assigned to a thread in the thread pool to execute, that is, the task is executed concurrently and does not affect each other.It is important to note that Scheduledexecutorservice only actually starts a thread when the dispatch task comes, and the rest of the

Scheduledexecutorservice extends the Executorservice interface, providing the ability to perform tasks regularly (like a timer). API Description method Desc Schedule (callable Creates and executes a scheduledfuture that is enabled after a given delay. Schedule (Runnable command, long delay, timeunit unit) Creates and executes a one-time operation that is enabled after a given delay. Sc

modified later, the program will continue to be executed based on taskfired = (executiontime 2. Since jdk1.5 is started, we can select scheduledexecutorservice to replace timer for scheduled tasks. Scheduledexecutorservice is not based on absolute time and cycle, but on time delay and cycle. In this way, when a time jump occurs (Network Delay/time server synchronization/manual intervention ), the sche

After Java5, the concurrent Threads section adds a lot of new things, a new start, dispatch, and management thread of a lot of API, at this time through executor to start the thread than Thread.Start () better, easier to control thread startup, destruction, etc., can also use the function of the thread pool.I. Creating a Taskis actually implementing the Runnable interface to implement the Run method.Two. Perform TasksThe task is performed through the Java.util.concurrent.ExecutorService interfac

implement, the specific invocation method is as follows: Timer timer = new timer (); Systemtimertask () task = new Systemtimertask (10001,20); About the schedule method declared as: Schedule (timertask task, long delay, long period) --task: Scheduled task; --delay: In milliseconds, indicates that the task is delayed delay milliseconds after execution; --period: In milliseconds, the duration of the task execution, which is the timer initial value.2, multithreading (

Everyone said that the timer is not very good, often encounter: if a task in front of the slow, beyond the period, then the next time the timer poll will not be delayed.Colleagues say Scheduleexecutorservice can avoid the problem, I write an example test under:Package Com.dx.testparallel;import Java.util.concurrent.executors;import Java.util.concurrent.scheduledexecutorservice;import Java.util.concurrent.TimeUnit; Public classTesttimer { Public Static voidMain (string[] args) {

maximum number of threads parameter controls the number of concurrent threads in the system.JAVA5 thread PoolJava5 built-in thread pool, the Executors factory class was added to generate the thread pool, which contains several static factory methods to create the threading pools.Executorservice Newcachedthreadpool () creates a buffer-capable thread poolExecutorservice Newfixedthreadpool (int n) creates a reusable thread pool with a fixed number of threadsExecutorservice Newsinglethreadexecutor

()-start)); } }; Timer timeR = new Timer (); Start = System.currenttimemillis (); Timer.schedule (Task1, 1000); Timer.schedule (TASK2, 3000); } }Execution Result:Task1 invoked! 1000Task2 invoked! 4000Newscheduledthreadpool:1. Multiple threads can perform different tasks at the same time.2, because it is a number of threads all, the task throws an exception, does not affect the execution of other tasks. After scheduleatfixedrate:0s, s

Scheduledexecutorservice Progressexecutorservice = Executors.newscheduledthreadpool (1); ScheduledfutureNewRunnable () {//It begins in 0.5 seconds, and executes once every second.@Override Public voidrun () {System.out.println ("Excel Download Progress:" +progress.get () + "%"); if(Progress.get () = = 100) {System.out.println ("Excel Download Progress is 100%"); Progressexecutorservice.shutdown (); } } }, (Long) 0.5, 1

Package com.taobao.vcloud.scheduler.job; Import Java.util.concurrent.ConcurrentHashMap; Import java.util.concurrent.Executors; Import Java.util.concurrent.Future; Import Java.util.concurrent.ScheduledExecutorService; Import

Scheduledthreadexecutor only supports relative time. Interface scheduleatfixedrate prototype definition and parameter description//public scheduledfuture scheduleatfixedrate (Runnable command,long Initialdelay,long period,timeunit unit); Command:

Thinking logic of computer programs (80) and thinking 80 This section describes scheduled tasks. There are many application scenarios for scheduled tasks, such: An alarm program or task reminder. You can call a bed at a specified time or return a credit card on a specified date. The monitoring system collects system data at intervals to trigger alarms for abnormal events. Statistical System, which usually collects various data indicators of yesterday at a certain time in the early morning.

;ExecutorService threadPoolExecutor = new ThreadPoolExecutor( corePoolSize, maxPoolSize, keepAliveTime, TimeUnit.MILLISECONDS, new LinkedBlockingQueueSecond, ScheduledthreadpoolexecutorScheduledthreadpoolexecutor is another implementation class of Executorservice, from the above Java thread pool Executorservice inheritance tree, as can be seen in the picture, Scheduledthreadpoolexecutor directly inherit from