[BUG]Segmentation fault(core dumped) error when use --fored-shutdown

[MANGOPIE3]

Hi, everyone. I find a Segmentation fault (core dumped) when use --fored-shutdown=1 option.
I read up the related code, and I have double point,

The analysis is as follows:

  if (sb_globals.force_shutdown)
  {
    /* Set the alarm to force shutdown */
    signal(SIGALRM, sigalrm_forced_shutdown_handler);

    alarm(NS2SEC(sb_globals.max_time_ns) + sb_globals.timeout);
  }

Look this free interm_slots process:
sigalrm_forced_shutdown_handler -> log_done -> sb_histogram_done -> free(interm_slots)

when one thread process sigalrm_forced_shutdown_handler, it will free interm_slots but other thread still can vist it.