A recipe for reproducing the error.
make -j [jobs]
main this_host [hosts...]
example:
for host 0: ./main 0 172.22.0.2 172.22.0.3
for host 1: ./main 1 172.22.0.2 172.22.0.3
The host 1 (right) doesn't receive the request from host 0 at iteration 342.