Java Multithreading Core Technology (note)-Thread priority

Introduction: In the operating system, threads can prioritize, high priority to obtain more CPU resources, that is, the CPU priority to execute higher priority threads. Priority of Threads in Java

Divide 1~~10 10 levels. is greater than or less than the reported exception.

One, the thread priority has inheritance

A thread initiates a B thread, then thread B has the same priority as a.

 public  class  MyThread1 extends   Thread {@Override   void   run () {System.out.println ( "MyThread1 run priority=" + this  .getpriority (        ));        MyThread2 thread2  = new   MyThread2 ();    Thread2.start (); }}

 public  class  MyThread2 extends   Thread {@Override   void   run () {System.out.println ( "MyThread2 run priority=" + this  .getpriority (    )); }}

 Public class Run {    publicstaticvoid  main (string[] args) {        System.out.println ( "Main thread begin priority="                + Thread.CurrentThread (). getpriority ());  \ \ Gets the priority        of the thread  // Thread.CurrentThread (). setpriority (6);           \ \ Sets the priority of the thread        System.out.println ("Main thread end   priority="                + Thread.CurrentThread (). GetPriority ());         New MyThread1 ();        Thread1.start ();    }}

Results:

Second, thread priority is rule-

 Public classMyThread1extendsThread {@Override Public voidrun () {LongBeginTime =System.currenttimemillis (); LongAddresult = 0;  for(intj = 0; J < 10; J + +) {             for(inti = 0; I < 50000; i++) {Random random=NewRandom ();                Random.nextint (); Addresult= Addresult +i; }        }        LongEndTime =System.currenttimemillis (); System.out.println ("★★★★★thread 1 Use time=" + (EndTime-beginTime)); }}

 Public classMyThread2extendsThread {@Override Public voidrun () {LongBeginTime =System.currenttimemillis (); LongAddresult = 0;  for(intj = 0; J < 10; J + +) {             for(inti = 0; I < 50000; i++) {Random random=NewRandom ();                Random.nextint (); Addresult= Addresult +i; }        }        LongEndTime =System.currenttimemillis (); System.out.println ("☆☆☆☆☆thread 2 Use Time=" + (EndTime-beginTime)); }}

 public  class   Run { public  static  void   main (string[] args) { for  (int  i = 0; I < 5; I++) {MyThread1 Thread1  = new   MyThread1 ();            Thread1.setpriority ( 1 = new   MyThread2 ();            Thread2.setpriority ( 10

The result: high-priority threads are always executed mostly first, run faster, and do not mean that the thread's priority is independent of the order in which the threads are executed. This results in a 10 times-fold difference in priority. Change to a similar priority then look, like.

Third, thread priority has randomness

Multiple runs of code with similar priority, you will find the following results appear: You can verify that the priority of a thread is random.

Daemon Thread (daemon)

Concept: Any daemon thread is a "nanny" for all non-daemon threads throughout the JVM. The daemon thread is working as long as there is a non-daemon thread in the current instance that does not end. When the last non-daemon thread ends

, the daemon thread will not end up working. (Typical, GC garbage collector)

Java Multithreading Core Technology (note)-Thread priority