Writing and analysing multi-threaded code on a Raspberry-pi

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <time.h>

// **NOTE** fprintf is used to print the messages to terminal and 'standard error
// stream' is used  instead 'standard output', this methods prints the messages 
// in the right sequence instead of buffering them to the end

void* Thread_1(void* arg) // Function for thread 1 
{
struct timeval t0, t1, time_diff;  // Used for testing the 
gettimeofday(&t0,NULL);             // actual time taken by the thread 
fprintf(stderr,"Entered the first thread\n");   
sleep(1);   // sleep for 1 second
gettimeofday(&t1,NULL);   //  time after 
timersub(&t1,&t0,&time_diff); // store the difference in before and after time
fprintf(stderr,"\nLeft the first thread\n"); 
fprintf(stderr,"doSomething (thread %ld) took %d.%06d sec\n",(long)pthread_self()
    ,time_diff.tv_sec,time_diff.tv_usec); // print time taken with the accuracy
                        // of microseconds 
pthread_exit(0); // exit the thread
}

void* Thread_2(void* arg) // Function for thread 2 
{
fprintf(stderr,"Entered the second thread\n"); 
sleep(7); // sleep for seven seconds
fprintf(stderr,"\nLeft the second thread\n");
pthread_exit(0); // exit the thread
}

void* Thread_3(void* arg) // Function for thread 3
{
fprintf(stderr,"Entered the third thread\n");
sleep(5); // sleep for five seconds
fprintf(stderr,"\nLeft the third thread\n");
pthread_exit(0);// exit thread
}


int main()
{
pid_t pid; // declare a variable 'pid' of type pid_t
pid =fork();// fork a child and parent process and assign the return value to 'pid' 

if(pid==0) // if inside child process (fork's return value zero means in child process)
{
char * path1="./first.sh"; // path for the first shell script
char * arg1[]={"./first",NULL}; // default argument needed by 'execvp' function
execvp(path1,arg1); // executes the 'first.sh' shell script
}

else if(pid > 0) // If Inside the parent process
{
//Thread ID
pthread_t tid1; // declare a variable 'tid1' of type pthread_t
pthread_t tid2; // declare a variable 'tid2' of type pthread_t
pthread_t tid3; // declare a variable 'tid3' of type pthread_t

//Create the threads
pthread_create(&tid1,NULL,&Thread_1,NULL);//initalize tid1 and run Thread_1 function 
pthread_create(&tid2,NULL,&Thread_2,NULL);//initalize tid1 and run Thread_1 function 
pthread_create(&tid3,NULL,&Thread_3,NULL);//initalize tid1 and run Thread_1 function 

//wait until the thread has done its work
pthread_join(tid1,NULL); // wait for thread with thread ID tid1, no return value needed
pthread_join(tid2,NULL); // wait for thread with thread ID tid1, no return value needed
pthread_join(tid3,NULL); // wait for thread with thread ID tid1, no return value needed
//sleep(10);
wait(NULL); // Wait for the child process to finish (If it hasn't)
}
else if(pid < 0) // If there was an error in forking
{
perror("Fork failed"); //Print an error messsage
exit(1); // exit with return value 1 
}

pid=fork(); // Create another child process and parent process  
if(pid == 0) // If in child process 
{
char *path2="./second.sh"; // path to second shell script
char *arg2[]={"./second",NULL}; // default argument needed for execvp
execvp(path2,arg2);// execute the 'second.sh' shell script 
}
else if(pid>0) 
{
wait(NULL); // wait for the child process to finish
printf("\nExiting the main loop\n"); 
}
}
//to compile we use  = gcc sum_on_t.c  -pthread -o some_name 
// we use the c99 format because we declared the variable in the for loop which can't be done in the linux C version

echo  "\nEntered the first shell script\n" #Announce that shell script is executed
top -H -b -n 1 |grep Threads > Threads.txt #run the top command in |thread mode '-H'|
# with |batch-mode text '-b'| and |run it once '-n 1'|
# Grab the line with 'Thread' word in the string 
#the Output is piped to Threads.txt file 

top -H -b -n 1 -w 14 |grep top >>Threads.txt  #run the top command in |thread mode '-H'|
# with |batch-mode text '-b'| and |run it once '-n 1'| with a width of 14 '-w 14'
#Grab the line with 'top' word in the line of string   
#the Output is piped to Threads.txt file 

echo  "This is the data put into the first text file\n"
 
cat Threads.txt # Output the contents of the text file

echo "\n"

C_prog_pid="$(pidof Thread_runner)" # Get the process Id of the executable Thread_runner

echo  "$C_prog_pid is the process ID of the running executable\n"

echo "\nEntered the second shell script\n"

    echo "This is the data put into the second text file\n"

    top -H -b -n 1 |grep Threads > Threads_after.txt #run the top command in |thread mode '-H'|
    # with |batch-mode text '-b'| and |run it once '-n 1'|
    # Grab the line with 'Thread' word in the string 
    #the Output is piped to 'Threads_after.txt' file 
    
    top -H -b -n 1  -w 14 |grep top >> Threads_after.txt  #run the top command in |thread mode '-H'|
    # with |batch-mode text '-b'| and |run it once '-n 1'| with a width of 14 '-w 14'
    #Grab the line with 'top' word in the line of string   
    #the Output is piped to Threads.txt file 
     
    cat Threads_after.txt  # Output the contents of the text file
    
    perl search_th.pl # Run the perl script to Output the data in a summarized fashion
    

#!/usr/bin/perl

use strict;  
use warnings;

print "\n\n THE PERL SCRIPT BEGINS \n\n"; #Annouce the entry into the perl script

my $Threads_total_before; # scalar variable for total threads in first text file
my $Threads_total_after; # scalar variable for total threads in the second text file
my $Threads_running; # scalar variable for running threads
my $Threads_sleeping; # scalar variable for running threads
my $start_minute; # scalar variable for start time's minute part
my $start_second; # scalar variable for start time's second part
my $end_minute; # scalar variable for end time's minute part
my $end_second; # scalar variable for end time's second part 
my @my_array; #array variable for storing the words in a row of a file
my @start_time; #array variable for storig the hours,minutes and secs of start time
my @end_time; #array variable for storing the hours,minutes and secs of end time 
my $row; #scalar variable for storing the row of a file

my $filename = 'Threads.txt'; # name of the text file to be read
open(my $fh,'<:encoding(UTF-8)',$filename) #Open 'Threads.txt' as a big string '$fh'
        or die "Could not open file '$filename' $!"; # exit with a message if file can't open

while( $row = <$fh>) #run a while loop with range equal to the number of rows in $fh string 
{
chomp $row; # Get rid of any empty newlines
@my_array=split(' ',$row); #split the words in the row based on 'spaces' and store them in @my_array  
if($row =~ /Threads/) # using regex '=~ //' determine if the word 'Thread' appears in the row
{
$Threads_total_before=$my_array[1]; #get the second element of @my_array which is total threads
$Threads_running=$my_array[3]; #get the fourth element of @my_array which is running threads
$Threads_sleeping=$my_array[5];# get the sixth element of @my_array which is sleeping threads
}
elsif($row =~ /top/) # using regex '=~ //' check if the word 'top' appears in the row
{
 @start_time=split(':',$my_array[2]); #split digits in the array based on ':' & store in @start_time  
 $start_minute=$start_time[1]; # store the 2nd element of @start_time, which is minutes
 $start_second=$start_time[2]; # store the 2nd element of @start_time, which is minutes
}

}

#      PRINT THE READINGS IN UNDERSTABDABLE TEXT
print "Total number of threads are $Threads_total_before\n";
print "$Threads_running of the $Threads_total_before are running\n";
print "$Threads_sleeping threads are taking a nap\n";
print "Start minute : $start_minute\n";
print "Start second : $start_second\n";

my $filename2 = 'Threads_after.txt'; # name of the second file to be read
open(my $fh2,'<:encoding(UTF-8)',$filename2)  #Open 'Threads_after.txt' as a big string '$fh2' 
        or die "Could not open file '$filename' $!"; # exit with a message if file can't open

while( $row = <$fh2>) # run a while loop with range equal to the number of rows in $fh2 string
{
chomp $row; # Get rid of empty newlines
@my_array=split(' ',$row); #split the words in the row based on 'spaces' and store them in @my_array
if($row =~ /Threads/)  # using regex '=~ //' check if the word 'Thread' appears in the row
{
$Threads_total_after=$my_array[1];#get the second element of @my_array which is total threads 
$Threads_running=$my_array[3];#get the fourth element of @my_array which is runnning threads
$Threads_sleeping=$my_array[5];#get the sixth element of @my_array which is sleeping threads
}
elsif($row =~ /top/)  # using regex '=~ //' check if the word 'Top' appears in the row
{
 @end_time=split(':',$my_array[2]); #split the words in the @my_array[2] based on ':'  

 $end_minute=$end_time[1]; # get the second element of end-time, which is minutes
 $end_second=$end_time[2]; # get the third element of end-time, which is seconds
}

}

#               PRINT THE DATA IN UNDERSTANDABLE TEXT
print "\nTotal number of threads are $Threads_total_after\n";
print "$Threads_running of the $Threads_total_after are running\n";
print "$Threads_sleeping threads are taking a nap\n";
print "End minute : $end_minute\n";
print "End second : $end_second\n";

# Get the number of threads spawned by comparing the total threads from both the text file
my $number_of_threads = $Threads_total_before - $Threads_total_after;
print "\n$number_of_threads threads were created by the executable\n";

#Get the time taken for all threads to finish executing by comparing time from both text files
if($end_minute == $start_minute) # If less than a minute was spent
{
 my $diff = $end_second - $start_second; # get the time difference
 print "\n$diff seconds were taken to complete all ",  
           "the threads spawned by the executable\n";
}
else # if more than a minute was taken
{
 my $diff = (($end_minute - $start_minute) * 60 ) + 
		($end_second - $start_second); # Get the time difference
 print "\n$diff seconds were taken to complete all ",
           "the threads spawned by the executable\n";	
}

print " \n\n PERL SCRIPT ENDS \n\n" # Announce the exit from perl script