pthread_create - segmentation fault

[vijiambav]

hi,
I've got a problem in using pthread_create(). I'm using Linux OS, version is 2.6.18. I wrote a C program:

#include <pthread.h>
int main()
{
int g_nThOutRet;
int g_nThInRet;
pthread_t thBuckIn,thBuckOut;

if(g_nThInRet = pthread_create(&thBuckIn,NULL,BucketIn,NULL))
perror("Thread Creation err of IN: ");
printf("\n after creat of IN \n");

pthread_join(thBuckIn,NULL);
printf("\n after join of IN in main \n");

usleep(1);

printf("\n b4 creat of OUT \n");
if(g_nThOutRet =
pthread_create(&thBuckOut,NULL,BucketOut,NULL)) // line # 19
perror("Thread Creation err of OUT: ");
printf("\n afr creat of OUT \n");
pthread_join(thBuckOut,NULL);
printf("\n after join of OUT in main \n");
return 0;
}

void * BucketOut()
{
printf("__BUCKET OUT__ \n");
}

void * BucketIn()
{
printf("__BUCKET IN__ \n");
}

I compiled using GCC and lpthread library. But I've a segmentation fault in call to pthread_create() of thBuckOut. The execution is as follows:

(gdb) run
Starting program: /home/viji/b
[Thread debugging using libthread_db enabled]
[New Thread -1208432960 (LWP 21834)]

[New Thread -1210537072 (LWP 21837)]

after creat of IN

__BUCKET IN___

after join of IN in main

b4 creat of OUT

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1208432960 (LWP 21834)]
0x48ee4517 in memset () from /lib/libc.so.6
(gdb) bt
#0 0x48ee4517 in memset () from /lib/libc.so.6
#1 0x48fea7e7 in pthread_create@@GLIBC_2.1 () from /lib/libpthread.so.0
#2 0x080487f7 in main () at b.c:19

What could be the problem for this segmentation fault? Pls help me...

[Franklin52]

Hi,

Declare the the variables thBuckOut and thBuckIn in main() as a pthread_t struct.
BTW place your code within code brackets!

Regards

[vijiambav]

I missed that declaration while posting. Where to include brackets? I didn't get any compilation errors.

[likwid]

He means when you post code on this board, put it in code brackets. It makes it formatted properly, so it's not so offensive to the eyes.

[Franklin52]

The 3th argument of pthread_create() must be a pointer to the thread function.
Try this:

#include <stdio.h>
#include <pthread.h>

void * BucketOut()
{
  printf("__BUCKET OUT__ \n");
}

void * BucketIn()
{
  printf("__BUCKET IN__ \n");
}

int main()
{
  int g_nThOutRet;
  int g_nThInRet;
  pthread_t thBuckIn,thBuckOut;

  if(g_nThInRet = pthread_create(&thBuckIn,NULL,&BucketIn,NULL))
    perror("Thread Creation err of IN: ");

  printf("\n after create of IN \n");

  pthread_join(thBuckIn,NULL);
  printf("\n after join of IN in main \n");

  usleep(1);

  printf("\n b4 create of OUT \n");

  if(g_nThOutRet = pthread_create(&thBuckOut,NULL,&BucketOut,NULL)) // line # 19
    perror("Thread Creation err of OUT: ");
 
  printf("\n after create of OUT \n");

  pthread_join(thBuckOut,NULL);
  printf("\n after join of OUT in main \n");

  return 0;
}

Regards

[vijiambav]

I tried passing pointer to the thread function as 3rd arg to pthread_create(). But that didn't solve the problem, segmentation fault is occuring.

[Franklin52]

On my system it works well, copy and paste the code in your box and add -lpthread to the command line e.g.

cc progname.c -o progname -lpthread

Regards

[vijiambav]

its working fine 4 me too. thanks a bunch