Re: Threads signalling issue [was RE: threads change]

Ignoring SMP write issues, I think that this code has a race condition
already:

Thread 1:                                      Thread 2:
void
Perl_despatch_signals(pTHX)
{
  dVAR;
  int sig;
  PL_sig_pending = 0;
  for (sig = 1; sig < SIG_SIZE; sig++) {
      if (PL_psig_pend[sig]) {
        PERL_BLOCKSIG_ADD(set, sig);
                                                PERL_BLOCKSIG_ADD(set, sig);
                                                PL_psig_pend[sig] = 0;
                                                PERL_BLOCKSIG_BLOCK(set);
                                                (*PL_sighandlerp)(sig);
                                                PERL_BLOCKSIG_UNBLOCK(set);
        PL_psig_pend[sig] = 0;
        PERL_BLOCKSIG_BLOCK(set);
        (*PL_sighandlerp)(sig);
        PERL_BLOCKSIG_UNBLOCK(set);
     }
  }
}

Signals are per process (unless I'm confused)

If a scheduler stops thread 1, and thread 2 runs the same code at the point
shown, then the intended protection of the blocked signals won't be there.

Nicholas Clark