Synchronization and deadlock of threads

If a thread pool is implemented through the Runnable interface, it means that the properties in the class will be shared by multiple threads, and the problem is the resource synchronization problem:

1. The delay of a thread causes other threads to operate on the resource share block either prematurely or later.

2. If multiple threads are in the process of determining the execution state of a problem, the thread becomes deadlocked.

The above problem can be resolved synchronously (note: Multiple threads need to synchronize when sharing the same resource, guaranteeing the integrity of the resource operation, but too much synchronization can cause deadlocks.)

Package Rubbableclass;/** Problems arising from delay functions in threads **/classMythread_eight implements runnable{Private intTicket =5; @Override Public voidrun () {//TODO Auto-generated method stubs         for(inti =0;i<Ten; i++){            if(ticket>0){                Try{Thread.Sleep (5); } Catch(Exception e) {//Todo:handle ExceptionE.printstacktrace (); } System. out. println ("Sell ticket: Ticket ="+ticket--); }        }    }    } Public classeigth { Public Static voidMain (string[] args) {//TODO Auto-generated method stubsMythread_eight my =Newmythread_eight (); Thread T1=NewThread (My,"Thread A-"); Thread T2=NewThread (My,"Thread-B"); Thread T3=NewThread (My,"thread C -");        T1.start ();        T2.start ();    T3.start (); }}

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Processing

1 Package Rubbableclass;2 /*3 * Synchronized operation is added.4  * */5 classMythread_nine implements runnable{6     Private intticket;7      PublicMythread_nine (intticket) {8         //TODO Auto-generated constructor stub9          This. Ticket =ticket;Ten     } One      A @Override -      Public voidrun () { -         //TODO Auto-generated method stubs the          for(inti =0; i<Ten; i++){ -Synchronized ( This) { -                 if(ticket>=0){ -                     Try { +Thread.Sleep (5); -}Catch(Exception e) { +                         //Todo:handle Exception A e.printstacktrace (); at}finally{ -System. out. println ("Sell ticket: Ticket ="+ticket--); -                     } -                 } -             } -         } in     } -      to } +  Public classNine { -  the      Public Static voidMain (string[] args) { *         //TODO Auto-generated method stubs $Mythread_nine my =NewMythread_nine (5);Panax NotoginsengThread T1 =NewThread (My,"Thread A-"); -Thread t2 =NewThread (My,"Thread-B"); theThread t3 =NewThread (My,"thread C -"); + T1.start (); A T2.start (); the T3.start (); +     } -  $}

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Deadlock problem

1 Package Rubbableclass;2 /*3 * New Even objects, a call Zhang San called John Doe, through the Zhang San and John Doe of borrowing and painting problems, resulting in deadlock problems4 * Zhang San: Want to draw, give me the picture, give you the book5 * John Doe: If you want a book, give me the book.6  * 7 * If both parties are waiting for each other's response then it is easy to create a deadlock state8  * */9 classzhangsan{Ten      Public voidsay () { OneSystem. out. println ("Zhang San said to John Doe, want the book to give me the picture! "); A     } -      Public voidgetpicture () { -System. out. println ("got a picture."); the     } - } -  - classlisi{ +      Public voidsay () { -System. out. println ("John Doe to Zhang San said: Want to draw the book to me! "); +     } A      Public voidGetBook () { atSystem. out. println ("got the book!"); -     } - } -  Public classTen implements runnable{ -     Private StaticZhangsan ZS =NewZhangsan (); -     Private StaticLisi ls =NewLisi (); in     PrivateBoolean flag =false;//used to judge who spoke first . - @Override to      Public voidrun () { +         //TODO Auto-generated method stubs -         //Suppose Zhang Sanxian spoke. the         if(flag) { * synchronized (ZS) { $ Zs.say ();Panax Notoginseng                 Try { -Thread.Sleep ( -); the}Catch(Exception e) { +                     //Todo:handle Exception A e.printstacktrace (); the }synchronized (LS) { + zs.getpicture (); -                 } $             } $         } -         Else{ - synchronized (LS) { the Ls.say (); -                 Try {WuyiThread.Sleep ( -); the}Catch(Exception e) { -                     //Todo:handle Exception Wu e.printstacktrace (); - }synchronized (ZS) { About Ls.getbook (); $                 } -             } -         } -          A     } +      the      Public Static voidMain (string[] args) { -         //TODO Auto-generated method stubs $Ten My1 =Newten (); theTen My2 =Newten (); theMy1.flag =true; theMy2.flag =false; the  -  inThread T1 =NewThread (My1); theThread t2 =NewThread (My2); the T1.start (); About T2.start (); the      the      the      +     } -  the}

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Synchronization and deadlock of threads