Concurrent thread state transition

Explain the transformation information according to the thread state transformation diagram sorted out before .

situation 1 NEW --> RUNNABLE

When calling t.start() When the method is used , from NEW --> RUNNABLE

situation 2 RUNNABLE <–> WAITING

t Thread use synchronized(obj) After getting the object lock

• call obj.wait() When the method is used ,t The thread from RUNNABLE --> WAITING
• call obj.notify() , obj.notifyAll() , t.interrupt() when
  • The competition is successful ,t The thread from WAITING --> RUNNABLE
  • The competition lock failed ,t The thread from WAITING --> BLOCKED

public class TestWaitNotify {
    
 final static Object obj = new Object();
 public static void main(String[] args) {
    
         new Thread(() -> {
    
         synchronized (obj) {
    
         log.debug(" perform ....");
         try {
    
         obj.wait();
         } catch (InterruptedException e) {
    
         e.printStackTrace();
         }
         log.debug(" Other code ...."); //  The breakpoint 
         }
         },"t1").start();
     
         new Thread(() -> {
    
         synchronized (obj) {
    
         log.debug(" perform ....");
         try {
    
         obj.wait();
         } catch (InterruptedException e) {
    
         e.printStackTrace();
         }
         log.debug(" Other code ...."); //  The breakpoint 
         }
         },"t2").start();

         sleep(0.5);
         log.debug(" Wake up the  obj  On other threads ");
         synchronized (obj) {
    
         obj.notifyAll(); //  Wake up the obj All waiting threads on   The breakpoint 
         }
     }
}  
/*  Running results : 08:10:09.924 c.TestWaitNotify [t1] -  perform .... 08:10:09.939 c.TestWaitNotify [t2] -  perform .... 08:10:10.346 c.TestWaitNotify [main] -  Wake up the  obj  On other threads  08:10:10.346 c.TestWaitNotify [t2] -  Other code .... 08:10:10.346 c.TestWaitNotify [t1] -  Other code .... */

explain :

1 When a thread t1 and t2 Successively compete to lock , Yes wait Method , State by RUNNABLE --> WAITING , Wait and release the lock .

2 Main thread sleep 0.5 Seconds later , Compete to lock , perform notifyAll Method , Wake up all other threads

3 t1 and t2 Threads compete for locks , A successful competition , State by WAITING --> RUNNABLE, Another competition failed , State by WAITING --> BLOCKED

4 t Release the lock after the thread executes , Another thread competes for the lock , Start execution , After execution , Thread by RUNNABLE <–> TERMINATED

situation 3 RUNNABLE <–> WAITING

Current thread call t.join() When the method is used , The current thread starts from RUNNABLE --> WAITING

• Is the current thread in t Wait on the monitor of the thread object

t End of thread run , Or called... Of the current thread interrupt() when , The current thread starts from WAITING --> RUNNABLE

situation 4 RUNNABLE <–> WAITING

Current thread call LockSupport.park() Method causes the current thread to run from RUNNABLE --> WAITING

call LockSupport.unpark( Target thread ) Or called a thread Of interrupt() , Will cause the target thread to run from WAITING --> RUNNABLE

situation 5 RUNNABLE <–> TIMED_WAITING

t Thread use synchronized(obj) After getting the object lock

• call obj.wait(long n) When the method is used ,t The thread from RUNNABLE --> TIMED_WAITING
• t Thread waiting time exceeded n millisecond , Or call obj.notify() , obj.notifyAll() , t.interrupt() when
  • The competition is successful ,t The thread from TIMED_WAITING --> RUNNABLE
  • The competition lock failed ,t The thread from TIMED_WAITING --> BLOCKED

situation 6 RUNNABLE <–> TIMED_WAITING

Current thread call t.join(long n) When the method is used , The current thread starts from RUNNABLE --> TIMED_WAITING

• Is the current thread in t Wait on the monitor of the thread object

The current thread has been waiting longer than n millisecond , or t End of thread run , Or called... Of the current thread interrupt() when , The current thread starts from TIMED_WAITING --> RUNNABLE

situation 7 RUNNABLE <–> TIMED_WAITING

Current thread call Thread.sleep(long n) , The current thread starts from RUNNABLE --> TIMED_WAITING

The current thread has been waiting longer than n millisecond , The current thread starts from TIMED_WAITING --> RUNNABLE

situation 8 RUNNABLE <–> TIMED_WAITING

Current thread call LockSupport.parkNanos(long nanos) or LockSupport.parkUntil(long millis) when , When the front line Cheng Cong RUNNABLE --> TIMED_WAITING

call LockSupport.unpark( Target thread ) Or called a thread Of interrupt() , Or waiting for a timeout , Will cause the target thread to run from TIMED_WAITING–> RUNNABLE

situation 9 RUNNABLE <–> BLOCKED

t Thread use synchronized(obj) If the race fails when an object lock is acquired , from RUNNABLE --> BLOCKED

a obj The synchronization block of the lock thread is executed , Will wake up all BLOCKED The threads of the , If one t Thread race success , from BLOCKED --> RUNNABLE , Other failed threads still BLOCKED

situation 10 RUNNABLE <–> TERMINATED

All the code of the current thread is running , Get into TERMINATED