Java-----about the use of thread pools

The related concepts of threading are not described here, please Baidu or Google's

For learning threads, I think it is better to start from the code, the premise is that there is a certain accumulation of technology, otherwise please close no longer see ~

Four ways to implement thread pooling.

① cache thread Pool, flexible recycling of idle threads if the thread pool is longer than required for processing, new thread if not recyclable

 Packagethread;ImportJava.util.concurrent.Executor;ImportJava.util.concurrent.ExecutorService;Importjava.util.concurrent.Executors;//cacheable thread pool, if the thread pool length exceeds processing needs, can flexibly reclaim idle threads, if not recyclable, the new thread Public classThreadPoolExceutorTest1 { Public Static voidMain (string[] args) {Executorservice cachedthreadpoll=Executors.newcachedthreadpool ();  for(inti = 0; I < 10; i++) {            Final intindex = 1; Try{thread.sleep (index* 10); } Catch(interruptedexception e) {//TODO auto-generated Catch blockE.printstacktrace (); } cachedthreadpoll.execute (NewRunnable () { Public voidrun () {System.out.println (index);        }            }); }    }}

② Create a thread pool that can handle the maximum number of concurrent threads, and the threads will wait in the queue

 Packagethread;ImportJava.util.concurrent.ExecutorService;Importjava.util.concurrent.Executors;//Create a thread pool that can handle the maximum number of concurrent threads, and the threads will wait in the queue Public classThreadPoolExecutorTest2 { Public Static voidMain (String []args) {Executorservice Fixedthreadpool=executors.newfixedthreadpool (3);  for(inti=0;i<10;i++) {            Final intIndex=1; Fixedthreadpool.execute (NewRunnable () { Public voidrun () {Try{System.out.println (index); Thread.Sleep (2000); } Catch(interruptedexception e) {//TODO auto-generated Catch blockE.printstacktrace ();        }                }            }); }    }}

③

Create a thread pool that supports timed and recurring task execution, with deferred execution examples as follows (3m after execution)

 Packagethread;Importjava.util.concurrent.Executors;ImportJava.util.concurrent.ScheduledExecutorService;ImportJava.util.concurrent.TimeUnit;//Create a thread pool that supports timed and recurring task execution, with deferred execution examples as follows (3m after execution) Public classThreadPoolExecutorTest3 { Public Static voidMain (String []args) {Scheduledexecutorservice Scheduledthreadpool=executors.newscheduledthreadpool (5); Scheduledthreadpool.schedule (NewRunnable () { Public voidrun () {System.out.println ("This is 3 demo"); }        },3, Timeunit.milliseconds); }}

Periodic execution delay of 1 seconds after 3 seconds

 Packagethread;Importjava.util.concurrent.Executors;ImportJava.util.concurrent.ScheduledExecutorService;ImportJava.util.concurrent.TimeUnit;//periodic execution delay of 1 seconds after 3 seconds Public classThreadPoolExecutorTest35 { Public Static voidMain (String []args) {Scheduledexecutorservice Scheduledthreadpool=executors.newscheduledthreadpool (5); Scheduledthreadpool.scheduleatfixedrate (NewRunnable () { Public voidrun () {System.out.println ("This is 3 demo"); }        },1,3, Timeunit.milliseconds); }}

④

A single threaded thread pool that performs tasks with only a single worker thread, ensuring that all tasks are executed in the specified order (FIFO, LIFO, priority).

 Packagethread;ImportJava.util.concurrent.ExecutorService;Importjava.util.concurrent.Executors;//a single threaded thread pool that performs tasks with only a single worker thread, ensuring that all tasks are executed in the specified order (FIFO, LIFO, priority). The sample code is as follows Public classThreadPoolExecutorTest4 { Public Static voidmain (String [] args) {Executorservice singlethreadexecutor=Executors.newsinglethreadexecutor ();  for(inti=0;i<10;i++) {            Final intindex=i; Singlethreadexecutor.execute (NewRunnable () { Public voidrun () {Try{System.out.println (index); Thread.Sleep (2000); } Catch(interruptedexception e) {//TODO auto-generated Catch blockE.printstacktrace ();        }                }            }); }    }}

　You can monitor the number of threads we create, run a non-terminating thread, and create a specified amount of threads by using the JDK's own monitoring tools to observe:

 Packagethread;ImportJava.util.concurrent.ExecutorService;Importjava.util.concurrent.Executors;//You can monitor the number of threads we create, run a non-terminating thread, and create a specified amount of threads by using the JDK's own monitoring tools to observe: Public classThreadPoolExecutorTest45 { Public Static voidMain (string[] args) {Executorservice singlethreadexecutor=Executors.newcachedthreadpool ();  for(inti = 0; I < 100; i++) {            Final intindex =i; Singlethreadexecutor.execute (NewRunnable () { Public voidrun () {Try {                         while(true) {System.out.println (index); Thread.Sleep (10 * 1000); }                    } Catch(interruptedexception e) {//TODO auto-generated Catch blockE.printstacktrace ();            }                }            }); Try{Thread.Sleep (500); } Catch(interruptedexception e) {//TODO auto-generated Catch blockE.printstacktrace (); }        }    }}

　Open the JDK with your own monitoring tool Jdk-bin-jconsole.exe, run as Administrator

　　

Threads can be viewed here ~, but the program must first run up ~

After the code is written ~ Do not understand can be hand-knocked a few times will deepen understanding

Java-----about the use of thread pools