Convert a normal python code to an MPI code

I have this code that I would like to edit and run it as an MPI code. The array in the code mass_array1 is a multi-dimensional array with total 'iterations' i*j around 80 million. I mean if I flatten the array into 1 dimensional array, there are 80 million elements.

The code takes almost 2 days to run which is quite annoying as it is only small part of the whole project. Since I can log into a cluster and run the code through 20 or so processors (or even more), can someone help me edit this code to an MPI code?

Even writing the MPI code in C language works.

#Alotting Black Holes at z=6
from tqdm import tqdm
bhs=[0]*1000

for i in tqdm(range(0,1000),leave=True):
    bhs[i]=np.zeros(len(mass_array1[i]))
    for j in range (len(mass_array1[i])):
        bhs[i][j]=np.random.lognormal(np.log(Mbhthfit6(mass_array1[i],6)[j]),np.log(5))

Current C program using MPI on that cluster:

int main(int argc,char **argv){
float epsran;
FILE *fp;
char str[256];
fp=fopen("parameterfile.dat","w");
fprintf(fp,
   " cosmological parameter\n"
       "h:%f\n"
   "omegam:%f\n"
   "omegab:%f\n"
   "omegal:%f\n"
   "sigma8:%f\n"
   "rho0mMpc:%e\n"
   "alpha:%f\n"
   "deltac:%f\n",ndh,
   omegam,omegab,omegal,sigma8,rho0mMpc,alpha,deltac);
fclose(fp);
/* MPI test */
int i,Petot,MyRank;
clock_t start,end;
start = clock();
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &Petot);
MPI_Comm_rank(MPI_COMM_WORLD, &MyRank);
srand((unsigned)(time(NULL)+MyRank));
//printf ("Hello World %d\n%d", MyRank,Petot);
float samples[100];
for(i=0;i<100/Petot;i++){
  samples[i]=halo_samples(1.68,1000);
    outputS(235,30,varipsapp(samples[i],0),MyRank*(100/Petot)+i);
}
printf("Length:%d",(int)(sizeof(samples)/sizeof(samples[0])));
/*    FILE *fpw;
fpw = fopen("Minitial.dat","w");
for(i=0;i<MyRank*(100/Petot);i++){
  fprintf(fpw,"%f\n",samples[i]);
  }
  fclose(fpw);*/
MPI_Finalize();
end = clock();
  }

Submitting a job

After this, there is a job.sh file that looks something like this:

#!/bin/sh     
#$ -S /bin/sh                                                                  
#$ -cwd                                          
#$ -V
#$ -N mergertree
#$ -q all.q@messier04
#$ -q all.q@messier05
#$ -pe openmpi10 20 
#$ -o resultfile/out.txt
#$ -e resultfile/error.txt
                                                       
mpirun -np $NSLOTS ./a.out

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