About Synchronization

• Synchronization is the key concept in multi threaded application.
• Synchronization prevent threads interference.
• Synchronization is to guarantee atomic access to critical section of code.
• Synchronization provides following three function.

1. Atomicity
2. Ordering
3. Visibility

• Synchronization is very important in JMM(Java Memory Model). It make the JVM to execute read 
• Barrier and write Barrier. 
• In read Barrier it invalidate the thread specific local memory ( processor cache or processor registers) and it make the processor to re read any variable used in synchronization block from main memory.
• Similarly, it makes the processor to execute write barrier to put back the thread local memory data back to main memory.
• It is recommended that synchronization code should be as minimum as possible.
• Synchronization can be apply to method or block or static method

synchronized method  
public synchronized void processData(){
}

synchronized block

public void processData(){
   synchronized(this){
   }
}

synchronized on static method

public synchronized  static void processData(){ 
}

synchronized block on class level lock

public static void processData(){
   synchronized(Processor.class){
   }
}