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javasynchronizationrmideadlock

java rmi deadlock

I just have started to program with java rmi and I face the following problem in my code:

My server has two Remote methods which are implemented in general as follows:

public class ServerImpl extends UnicastRemoteObject implements Server{
      ....
      Synchronized void  foo(){ aClient.Foo3();}
      Synchronized void  foo1(){ .... }
 }

My clients have one remote method which is implemented as follows:

public class ClientImpl extends UnicastRemoteObject implements Client{
      ....
      void Foo3(){theServer.foo1();}
}

So when aClient calls server's foo(), the server calls client's Foo3() and then aClient wants to call server's foo1() and we have a deadlock (neither the server nor the client moves on). I know that this is caused because of the Synchronized keyword. The problem is that these methods have to be Synchronized (I don't want two threads the same time in there), and I don't have the slightest idea of how to resolve this issue. Any help appreciated.

Thank you very much!

Solution

  • You can use a synchronized block with different locking object inside each method. synchronized methods lock on this so only one may be visited at a time.