[Beowulf] MPI synchronization problem

[Michel Dierks]

Hello,

I'm developing an application to calculate the Mandelbrot fractal.

My problem is:

from the master I will send to each free node for computation a message 
containing the values of one screen line.
After a time the nodes will send back the results.

I have see that I can use MPI_Isend and MPI_Irecv for non-blocking 
communication. This give me no problem if we are talking about of one 
send and one receive. But how can I handle the sending from each node to 
the master without  data corruption.
Must I implement a send and a receive buffer for each node (16 nodes 
means 16 buffer in and 16 out) ?

Can someone help me? Please