I am using Open MPI to do data transfer from master node to worker nodes. 

But, the worker node can the data which is not what it should get. 

I have checked destination node rank, taskTag, datatype, all of them 
are correct. 

I do an experiment. 

Node 0 sends data to node 1 , 2 ,3. 

Only node 3 can get correct data, but node 1 and 2 get the wrong data, which
should be received by node 3. 

What is the possible reason ? 

I have printed out the data that is sent by master node. They are exactly 
what the node 1 , 2, 3 should receive. 

But why node 1 and 2 get data of node 3. 

Any help is appreciated.