Hi
How can I create writer threads and reader pthreads in c++ which share global data?
Any help will be greatly appreciated.
Thanks

This should get you started, it is a few blocks of code pulled from an OS idea I had a few years ago.

#include <iostream.h>
#include <unistd.h>
#include <pthread.h>
#include <stdio.h>
#include "myrandom.h"

#define MAX 90000

// Shared data between threads
int myarr[MAX];

#ifdef USE_LOCK
pthread_mutex_t global_lock;
#endif

void *ProcessGroup1 ( void *arg );

int main ( int argc, char *argv[] )
{

*** populate array code ***
// Start the threads
void *res1, *res2, *res3;
pthread_t thr1, thr2, thr3;
double arg1, arg2, arg3;
arg1 = 1; arg2 = 2; arg3 = 3;

#ifdef USE_LOCK
pthread_mutex_init( &global_lock, NULL );
#endif

pthread_create( &thr1, NULL, ProcessGroup1, &arg1 );
pthread_create( &thr2, NULL, ProcessGroup2, &arg2 );
pthread_create( &thr3, NULL, ProcessGroup3, &arg3 );

pthread_join( thr1, &res1 );
pthread_join( thr2, &res2 );
pthread_join( thr3, &res3 );

#ifdef USE_LOCK
pthread_mutex_destroy( &global_lock );
#endif

*** Output code ***
}

// Processing Group 1 of 3
void *ProcessGroup1 ( void *arg )
{
#ifdef USE_LOCK
pthread_mutex_lock( & global_lock );
#endif
sumGroup1 = PartialSum(0, FIRST_THIRD-1, myarr);
avgGroup1 = sumGroup1 / MAGIC_NUM;
#ifdef USE_LOCK
pthread_mutex_unlock( & global_lock );
#endif
return 0;
}

*** Other Processing functions ***
*** Opeational functions ***

Well, my code formatting is not that bad guys... Guess I need to use the code posting deal on the forum...

#include <iostream.h>
#include <unistd.h>
#include <pthread.h>
#include <stdio.h>
#include "myrandom.h" 

#define MAX 90000 

// Shared data between threads
int myarr[MAX]; 

#ifdef USE_LOCK
pthread_mutex_t global_lock;
#endif 

void *ProcessGroup1 ( void *arg ); 

int main ( int argc, char *argv[] )
{

*** populate array code ***
// Start the threads
void *res1, *res2, *res3;
pthread_t thr1, thr2, thr3;
double arg1, arg2, arg3;
arg1 = 1; arg2 = 2; arg3 = 3; 

#ifdef USE_LOCK
pthread_mutex_init( &global_lock, NULL );
#endif 

pthread_create( &thr1, NULL, ProcessGroup1, &arg1 );
pthread_create( &thr2, NULL, ProcessGroup2, &arg2 );
pthread_create( &thr3, NULL, ProcessGroup3, &arg3 ); 


pthread_join( thr1, &res1 );
pthread_join( thr2, &res2 );
pthread_join( thr3, &res3 ); 

#ifdef USE_LOCK
pthread_mutex_destroy( &global_lock );
#endif

*** Output code ***
} 

// Processing Group 1 of 3
void *ProcessGroup1 ( void *arg )
{
#ifdef USE_LOCK
pthread_mutex_lock( & global_lock );
#endif
sumGroup1 = PartialSum(0, FIRST_THIRD-1, myarr);
avgGroup1 = sumGroup1 / MAGIC_NUM;
#ifdef USE_LOCK
pthread_mutex_unlock( & global_lock );
#endif
return 0;
} 

*** Other Processing functions ***
*** Opeational functions *** 

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Well.. that was really no better. At anyrate, before I over kill this post trying to get the stucture of my code readable... I'll leave it at that. I'm sure you can follow it.

Infinite Recursion

Thank you very much for very detailed answer.
I really appreciate that.

You're welcome Priti. Good luck with Pthreads, they're fairly interesting.

Infinite Recursion