Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > On 2016-08-01 18:09:03 -0400, Robert Haas wrote: > >> (Also vaguely on the list of things to clean up: can't we make it so > >> that bgworkers aren't launched from inside a signal handler? Blech.) > > > Isn't pretty much everything on-demand below postmaster started from a > > signal handler? > > I think it depends. As an example, maybe_start_bgworker is called > from PostmasterMain, *and* from ServerLoop, *and* from reaper, > *and* from sigusr1_handler. That's likely excessive, but it's what > we've got at the moment.
As I recall, each of those calls correspond to some particular need; keep in mind that bgworkers can request to be started at a few different points: either right at postmaster start, or when consistent state is reached on a standby, or when recovery is finished. maybe_start_bgworker only starts one bgworker, and it also sets a flag so that ServerLoop will call it another time if there are pending workers for the same timing event. That explains the four calls to maybe_start_bgworker, and as I recall removing any of these would break some possible usage. And yes, I did put two of these in signal handlers precisely because that is postmaster's longstanding practice. (It's perhaps possible to remove the call from ServerLoop if you make maybe_start_bgworker process all of them at once instead, but as I recall we decided to do only one at a time so that ServerLoop had a chance to run other control logic in between, just in case.) -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
