[Beowulf] MPI list of free nodes

[Dierks Michel]

Hello,

I'm actually busy to develop an application to calculate the Mandelbrot
fractals.
I'm using a Beowulf cluster of three nodes and a master.
I use MPICH as communication library.

In my application, I send one line of the complex plan to one node.
Before that I must know which node are free to work.

My question is: how must I handled the list of the free node?

Must I each time that I will send a job to a node send a broadcast
message to know which nodes are free; is it not a waste of communication
time?
or
Must I handle a list (a file) of the nodes who are in status "working"
or "free".

Can someone give me informations about this aspect?

Thanks for your help