From: Sergei Golubchik
Date: April 24 2011 9:04pm
Subject: Re: Use of thread specific data with mysqld
List-Archive: http://lists.mysql.com/internals/38309
Message-Id: <20110424210456.GA9848@janus.mylan>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii

Hi, Hiromichi!

On Apr 24, Hiromichi Watari wrote:
> Hi,
> I'm trying to use thread specific data with mysqld but ran into a problem with my_errno generating Segmentation fault at the following line.
> I know that my_errno is also thread specific data but not familiar with its implementation.
> I'm using pthread_key_create(), pthread_setspecific() and pthread_getspecific() for my own thread specific data, is there something I should be aware of ?
> Thanks,
> Hiromichi
> 
> p.s. I ran into this problem only if I try to use my own thread specific data, of course.

probably you forgot to call my_thread_init() in the beginning of your
thread function.

Anyway, here's the code:

#define my_errno my_thread_var->thr_errno

#define my_thread_var (_my_thread_var())

struct st_my_thread_var *_my_thread_var(void)
{
  return  my_pthread_getspecific(struct st_my_thread_var*,THR_KEY_mysys);
}

my_bool my_thread_init(void)
{
  ...
    if (!(tmp= (struct st_my_thread_var *) calloc(1, sizeof(*tmp))))
    {
      error= 1;
      goto end;
    }
    pthread_setspecific(THR_KEY_mysys,tmp);
  ...
}

Regards,
Sergei