Winbatch wrote:[color=blue]
> Hi, I'm trying to learn multithreading and it doesn't seem to be[/color]
working for[color=blue]
> me. I have a feeling it has to do with the fact that I'm writing to[/color]
files[color=blue]
> rather than to printf, but maybe not. Basically, I wanted to see if[/color]
it[color=blue]
> would be faster to write to 4 files at the same time (parallel)[/color]
rather than[color=blue]
> 4 in a row (serially). however, when my multithreaded code executes,[/color]
it[color=blue]
> seems to do them in order anyway (I expected to see Starting/Ending[/color]
all[color=blue]
> mixed rather than in order). Does anyone know what I'm doing wrong?[/color]
(Note,[color=blue]
> I also tried to do it with 4 different functions (ie, go, go1, go2,[/color]
etc..,[color=blue]
> but that didn't seem to fix it).
>
> See code below and output below.
> #include "stdio.h"
> #include <pthread.h> /* pthread functions and data structures */
>
> void * go ( void * data1 )
> {
> long i=0;
> FILE * file;
> char * name;
> name = (char *) data1;
> printf( "Starting '%s'\n", name );
> file = fopen( name, "w" );
>
> for ( i=0;i< 10000000;i++)
> {
> fprintf( file, "%ld\n", i );
> }
> fclose(file);
> printf( "Ending '%s'\n", name );
> pthread_exit(0);
>
>
> }
> int main()
> {
> int thr_id, thr_two, thr_three, thr_four; /*[/color]
thread[color=blue]
> ID for the newly created thread */
> pthread_t p_thread, thread2, thread3,thread4; /* thread's
> structure */
> char a1[]="a1";
> char b1[]="b1";
> char c1[]="c1";
> char d1[]="d1";
> printf( "Creating threads...\n" );
> thr_id = pthread_create(&p_thread, NULL, go, (void*)&a1);
> printf( "Creating thread 2. ..\n" );
> thr_two = pthread_create(&thread2, NULL, go, (void*)&b1);
> printf( "Creating thread 3. ..\n" );
> thr_three = pthread_create(&thread3, NULL, go, (void*)&c1);
> printf( "Creating thread 4. ..\n" );
> thr_four = pthread_create(&thread4, NULL, go, (void*)&d1);
> pthread_join(p_thread, 0);
> pthread_join(thread2, 0);
> pthread_join(thread3, 0);
> pthread_join(thread4, 0);
> return 0;
> }
>
>
> cc -mt MultiTest.c -o MultiTest
>
> /export/CUST/systems/dan/process/development/MultiThread> ./MultiTest
> Creating threads...
> Creating thread 2. ..
> Creating thread 3. ..
> Creating thread 4. ..
> Starting 'a1'
> Ending 'a1'
> Starting 'b1'
> Ending 'b1'
> Starting 'c1'
> Ending 'c1'
> Starting 'd1'
> Ending 'd1'[/color]
Try this.
#include<stdio.h>
#include<windows.h>
#define MAX_M 4
// define max file to open
// thread function
DWORD WINAPI ThFunc(PVOID pvParam){
DWORD dwResult = 0;
char * name ;
long i=0;
FILE * file;
name =( char*)pvParam;
printf( "Starting '%s'\n", name );
file = fopen( name, "w" );
for ( i=0;i< 10000000;i++)
{
fprintf( file, "%ld\n", i );
}
fclose(file);
return(dwResult);
}
VOID main(VOID){
int cnt;
int redak[MAX_M];
char a1[]="a1";
char b1[]="b1";
char c1[]="c1";
char d1[]="d1";
HANDLE hThreads[MAX_M];// handles to threads
//see prototype of CreateThread
function)
DWORD dwThreadID[MAX_M];// need for ID-s
// create thread 1(0) see arguments
hThreads[0] = CreateThread(NULL,0,ThFunc,(PVOID)a1,0,&dwThreadID );
hThreads[1] = CreateThread(NULL,0,ThFunc,(PVOID)b1,0,&dwThreadID );
hThreads[2] = CreateThread(NULL,0,ThFunc,(PVOID)c1,0,&dwThreadID );
hThreads[3] = CreateThread(NULL,0,ThFunc,(PVOID)d1,0,&dwThreadID );
// wait until they finish their job , wait INFINITE
WaitForMultipleObjects(MAX_M,hThreads,TRUE,INFINIT E);
//closing handles to thread
for(cnt=0; cnt < MAX_M; cnt++){
printf("Closing thread %d ....\n",cnt);
CloseHandle(hThreads[cnt]);
}
}
I hope I have helped you and if you have futher questions about this
code send me them by mail.
Best regards
Sinisa
