On Sat, Aug 28, 2021 at 3:28 AM Andres Freund <and...@anarazel.de> wrote: > > > On Fri, Aug 27, 2021 at 7:31 AM Michael Paquier <mich...@paquier.xyz> wrote: > > > > > Wouldn't it be better to block things at the source, as of > > > RegisterBackgroundWorker()? And that would keep track of the control > > > we have on bgworkers in a single place. I also think that we'd better > > > document something about that either in bgworker.sgml or pg_upgrade's > > > page. > > Isn't that just going to end up with extension code erroring out and/or > blocking waiting for a bgworker to start?
But there's no API to wait for the start of a non-dynamic bgworker or check for it right? So I don't see how the extension code could wait or error out. As far as I know the only thing you can do is RegisterBackgroundWorker() in your _PG_init() code and hope that the server is correctly configured. The only thing that third-party code could I think is try to check if the bgworker could be successfully registered or not as I mentioned in [1]. Maybe extra paranoid code may add such check in all executor hook but the overhead would be so terrible that no one would use such an extension anyway. [1] https://www.postgresql.org/message-id/CAOBaU_ZtR88x3Si6XwprqGo8UZNLncAQrD_-wc67sC=acO3g=w...@mail.gmail.com
