PMPI_Waitall error - c++

Question

i've some problems with this piece of code.
NEIGHBOORDHOOD_FLAG = 1234;
int number_of_nodes=90;
MPI_Request neig_request[2*number_of_nodes];
MPI_Status neig_status[2*number_of_nodes];
int neig_counter=0;
int is_neighbour_send[number_of_nodes];
int is_neighbour_receive[number_of_nodes];
for(int v=2;v<number_of_nodes+2;++v){
is_neighbour_send[v-2] = (util.check_targets(neighbours,v)==true)?1:0;
this->communicate_neighborhood(&(is_neighbour_send[v-2]),v,&(neig_request[neig_counter]));
++neig_counter;
}
//ricevo la comunicazione dai nodi per sapere di chi sono vicino
for(int v=2;v<number_of_nodes+2;++v){
this->receive_neighborhood(&(is_neighbour_receive[v-2]),v,&(neig_request[neig_counter]));
++neig_counter;
}
MPI_Waitall(neig_counter,neig_request,neig_status);
The two methods above are essentially two wrapped versions of the MPI send and receive:
void NodeAgent::communicate_neighborhood(int *neigh,int dest_node,MPI_Request *req){
MPI_Class::send_message(neigh,MPI_INT,1,dest_node,NEIGHBOORDHOOD_FLAG,req);
}
void NodeAgent::receive_neighborhood(int *is_neighbour,int node_mitt,MPI_Request *req){
MPI_Class::receive_message(is_neighbour,MPI_INT,1,node_mitt,NEIGHBOORDHOOD_FLAG,req);
}
with send and receive static methods:
void MPI_Class::send_message(void *content,MPI_Datatype datatype,int length,int dest,int tag,MPI_Request *request){
int np = MPI_Class::count();
MPI_Isend(content, length, datatype, (dest % np), tag, MPI_COMM_WORLD, request);
}
void MPI_Class::receive_message(void *buffer,MPI_Datatype datatype,int length,int dest,int tag,MPI_Request *request){
int np = MPI_Class::count();
MPI_Irecv(buffer,length,datatype,(dest % np),tag,MPI_COMM_WORLD,request);
}
The number of nodes is the number of processes - 2 (there are two processes that i use for others operations) and i've used the " % " in send and receive to ensure that the sender and the recipient are always in the range that i want.
The interesting thing is that this code executes properly also with large number of process (100). The problem arises when i launch the program on two machines or more...
It gives me: Fatal error in PMPI_Waitall: See the MPI_ERROR field in MPI_Status for the error code
I tried to print the MPI_ERROR of each status, but are all zeroes...
Can someone help me?
many thanks in advance
Edit, here the MCVE:
#include <mpi.h>
#include <stdlib.h>
int main(int argc,char **argv){
MPI_Init(&argc,&argv);
int my_id;
MPI_Comm_rank(MPI_COMM_WORLD, &my_id);
int world_size;
MPI_Comm_size(MPI_COMM_WORLD, &world_size);
MPI_Status * statuses = (MPI_Status *)malloc(2*world_size * sizeof(MPI_Status));
MPI_Request * requestes = (MPI_Request *)malloc(2*world_size * sizeof(MPI_Request));
int counter =0;
int *tosend = (int *) malloc((world_size - 2) * sizeof(int));
int *toreceive = (int *) malloc((world_size - 2) * sizeof(int));
for(int i=0;i<world_size-2;++i){
tosend[i]=0;
}
if(my_id>1){
for(int i=2;i<world_size;++i){
MPI_Isend(&tosend[i-2],1,MPI_INT,i,0,MPI_COMM_WORLD,&requestes[counter]);
++counter;
}
}
if(my_id>1){
for(int i=2;i<world_size;++i){
MPI_Irecv(&(toreceive[i-2]),1,MPI_INT,i,0,MPI_COMM_WORLD,&(requestes[counter]));
++counter;
}
}
MPI_Waitall(counter,requestes,statuses);
free(statuses);
free(requestes);
free(tosend);
free(toreceive);
MPI_Finalize();
}
Also this code executes correctly on a single machine. The problem arises when i launch it on 2 machines mutual authenticated (ssh). I just discovered that after the MPI_Waitall fatal error, if i try to connect via ssh from a machine to other, it ask me the password....
Why? At this point i think the problem is the communication via ssh and not the code..
Edit2: solved! it was a ssh problem that i solved in some way (i don't know how honestly, i redid the authentication procedures ten times as long as it worked....