Java multi-thread when a thread executes a dead loop, does it affect another thread?

One, the problem description

Assuming that there are two threads running concurrently, one thread executes code that contains a dead loop such as: while (true) .... When the thread executes the code in while (true), does the other thread have a chance to execute?

Two, sample code (code from the Internet)

1  Public classService {2Object Object1 =NewObject ();3 4      Public voidMethodA () {5         synchronized(object1) {6SYSTEM.OUT.PRINTLN ("MethodA Begin");7             BooleanIscontinuerun =true;8             //to perform a dead loop here9              while(iscontinuerun) {Ten                  One             } ASystem.out.println ("MethodA End"); -         } -     } the  -Object Object2 =NewObject (); -  -      Public voidMethodB () { +         synchronized(object2) { -SYSTEM.OUT.PRINTLN ("MethodB Begin"); +System.out.println ("MethodB End"); A         } at     } -}

The implementation of the two thread classes is as follows:

1 Importservice. Service;2 3  Public classThreadaextendsThread {4 5     PrivateService service;6 7      PublicThreada (Service service) {8         Super();9          This. Service =Service;Ten     } One  A @Override -      Public voidrun () { - Service.methoda (); the     } -  -}

Thread A executes MethodA (), there is a dead loop in MethodA ()

1 Importservice. Service;2 3  Public classThreadbextendsThread {4 5     PrivateService service;6 7      Publicthreadb (Service service) {8         Super();9          This. Service =Service;Ten     } One  A @Override -      Public voidrun () { - Service.methodb (); the     } -  -}

Thread B executes MethodB (), and when thread a enters the while loop in MethodA (), can execution of thread B be completed?

Test class

1 Importservice. Service;2 ImportExtthread. Threada;3 ImportExtthread. threadb;4 5  Public classRun {6 7      Public Static voidMain (string[] args) {8Service service =NewService ();9 TenThreada Athread =NewThreada (service); One Athread.start (); A  -THREADB Bthread =Newthreadb (service); - Bthread.start (); the     } -  -}

Execution Result:

Since thread A and thread B acquire an object lock that is not the same lock, it can be seen from the result that thread B can be executed. Thread A continues to run (the entire program is not finished) because it enters the while loop, but thread B ends.

That is, although thread A has been executing in while, it requires CPU usage. However, the scheduling of threads is the responsibility of the JVM or the operating system, not that thread A has been in while, and then thread B is not taking up CPU.

If the Service.java is modified as follows:

1  Public classService {2 //Object Object1 = new Object ();3 4      Public voidMethodA () {5         synchronized( This) {6SYSTEM.OUT.PRINTLN ("MethodA Begin");7             BooleanIscontinuerun =true;8             //to perform a dead loop here9              while(iscontinuerun) {Ten                  One             } ASystem.out.println ("MethodA End"); -         } -     } the  - //Object object2 = new Object (); -  -      Public voidMethodB () { +         synchronized( This) { -SYSTEM.OUT.PRINTLN ("MethodB Begin"); +System.out.println ("MethodB End"); A         } at     } -}

If thread a obtains an object lock first, thread A has been in the while loop because of the while cycle. Thread B cannot execute MethodB () because it cannot get a lock.

As you can see, if a thread cannot exit in the Synchronized method, the lock cannot be freed, and the other thread can only wait indefinitely.

Java multi-thread when a thread executes a dead loop, does it affect another thread?