Guest Author: Nisarg Negi, M.S. Data Science, UB
Peersim is an open-source simulator for large-scale peer-to-peer systems. It can be used to design and test large-scale machine-learning algorithms. One example is a large-scale, Support Vector Machine algorithm -- Gossip-bAseD sub-GradiEnT SVM (Source Code). The ready-to-use implementation of gossip-based protocols on the simulator is a powerful alternative to serverless Federated Learning environments.
Visualizing the graph structure in Peersim is often a cumbersome task. The following description provides one example of how this can be accomplished. We assume that the graph will be generated using the wireKOut configuration:
network.size 5
network.node.size 5
network.node.dim 4932
network.node peersim.gossip.PegasosNode
network.node.resourcepath data/sido
network.node.lambda 0.0001
network.node.maxiter 1
network.node.examperiter 1
degree 2
protocol.0 peersim.core.IdleProtocol
protocol.0.cache degree
protocol.1 peersim.gossip.GadgetProtocol
protocol.1.linkable 0
# learning rate and iter for GADGET, keep lambda smaller and iter larger
protocol.1.lambda 0.0001
protocol.1.iter 1
protocol.1.prot pushsum1
protocol.1.prot pushSV
protocol.1.method randomr
protocol.1.param 1
init.0 peersim.dynamics.WireKOut
init.0.protocol 0
init.0.k degree
For this, we had to modify some components of the peersim GraphFactory library. Since the code runs from the configuration file, more than simple editing of our code would be required.
We call GraphIO and create this graph, but we modified the library.
In the GraphFactory, after the graph is generated we call the GraphIO function and pass our randomly generated graph as a parameter. GraphIO returns the Graph saved in DOT format as below:
We saved the above configuration in a text file. On Unix systems, we can install graphviz:
sudo apt install graphviz
and utilize it to convert the text output graph to a better-visualized graph with the command:
dot -Tpng network_digraph_output.txt -o graph.png
The following code changes are required in the wireKOut function:
public static Graph wireKOut( Graph g, int k, Random r ) {
final int n = g.size();
if( n < 2 ) return g;
if( n <= k ) k=n-1;
int[] nodes = new int[n];
for(int i=0; i<nodes.length; ++i) nodes[i]=i;
for(int i=0; i<n; ++i)
{
int j=0;
while(j<k)
{
int newedge = j+r.nextInt(n-j);
int tmp = nodes[j];
nodes[j] = nodes[newedge];
nodes[newedge] = tmp;
if( nodes[j] != i )
{
g.setEdge(i,nodes[j]);
j++;
}
}
}
///Code to print the graph network
try {
System.out.print("\n GraphFactory:"+ g.toString()+ "\n");
peersim.graph.GraphIO.writeDOT(
g,System.err);
} catch (Exception e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {//saving network digraph to file
//Can use graphviz to print it, linux commands below:
//sudo apt install graphviz
//dot -Tpng network_digraph_output.txt -o graph.png
FileOutputStream fos = new FileOutputStream("network_digraph_output.txt");
PrintStream ps = new PrintStream(fos);
peersim.graph.GraphIO.writeDOT(g,ps);
fos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return g;
}
