声明为另一个类的静态成员的类对象的方法的线程行为

Question

Recently a colleague of mine came up with a piece of code and asked my opinion regarding thread safety of the code. Below is an example that illustrates the same scenario as the code.

public class classA
{
   public int DoWorkA() 
   { 
       //some logic 
   }
}

public class classB
{
     public static classA objA = new classA();
}

public class classC
{
        int DoWorkC () 
        {

           return classB.objA.DoWorkA();

        }
}

Now if ClassB.objA.DoWorkA() is called simulatenously in different instances of different classes like ClassC, ClassD etc will there be any threading or 'overlap' issues ? Should objA be converted into an instance member ?

Answer 1

Since objA is static there will be just a single instance of classA . That means all threads access the method DoWorkA() on the same instance , it does not mean however that the method call is thread-safe - that entirely depends on the implementation of DoWorkA() .

You will still need appropriate logic in DoWorkA to protect from problems that can arise with concurrent access, eg the use of locking or thread-safe collections etc.

Answer 2

will there be any threading or 'overlap' issues

It depends on what //some logic does. Each call will share the same instance, so DoWorkA would need to be thread safe in order for this to function correctly.

Any data used within //some logic needs proper synchronization for this to be safe.