On Thu, Aug 22, 2024 at 9:50 PM Tom Lane <t...@sss.pgh.pa.us> wrote:
> > > The previous postmaster coding blocked signals > > everywhere except immediately around the main loop's select() call, > > so there wasn't any real hazard of signal handlers interrupting > > anything of concern. We redid it for cleanliness, not because there > > was any observable bug. > > Agreed, signal handlers are very sensitive (at least as of this moment) and the current approach looks very clean and safe. > No, it was not. > (If there had been a bug there, ProcessConfigFile would have been > the least of our problems, because all the other postmaster signals > were handled in the same style.) Just as an info for future readers, it is indeed a bug for two reasons 1. changin GUC values in the signal handler, compiler might optimise the values so main control wouldn't have know about it later (90% sure about this) 2. *ProcessConfigFile* calls *AllocSetCreate* which in turn calls *malloc* which is not async signal safe(see man 7 signal-safety) and can cause deadlock in certain situations. (Dig malloc internal code if interested) Not only in *SIGHUP *handler it is done in other handlers as well. Feel free to correct me if there is any inaccuracy in what I said. Regards, Narayana
