Re: recovery modules
От | Nathan Bossart |
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Тема | Re: recovery modules |
Дата | |
Msg-id | 20230214005558.GA1145703@nathanxps13 обсуждение исходный текст |
Ответ на | Re: recovery modules (Andres Freund <andres@anarazel.de>) |
Ответы |
Re: recovery modules
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Список | pgsql-hackers |
On Mon, Feb 13, 2023 at 03:37:33PM -0800, Andres Freund wrote: > On 2023-02-13 14:56:47 -0800, Nathan Bossart wrote: >> On Mon, Feb 13, 2023 at 04:37:10PM +0900, Michael Paquier wrote: >> > + basic_archive_context = data->context; >> > + if (CurrentMemoryContext == basic_archive_context) >> > + MemoryContextSwitchTo(TopMemoryContext); >> > + >> > + if (MemoryContextIsValid(basic_archive_context)) >> > + MemoryContextDelete(basic_archive_context); >> > >> > This is a bit confusing, because it means that we enter in the >> > shutdown callback with one context, but exit it under >> > TopMemoryContext. Are you sure that this will be OK when there could >> > be multiple callbacks piled up with before_shmem_exit()? shmem_exit() >> > has nothing specific to memory contexts. >> >> Well, we can't free the memory context while we are in it, so we have to >> switch to another one. I agree that this is a bit confusing, though. > > Why would we be in that memory context? I'd just add an assert documenting > we're not. > > >> On second thought, I'm not sure it's important to make sure the state is >> freed in the shutdown callback. It's only called just before the archiver >> process exits, so we're not really at risk of leaking anything. I suppose >> we might not always restart the archiver in this case, but I also don't >> anticipate that behavior changing in the near future. I think this >> callback is more useful for things like shutting down background workers. > > I think it's crucial. Otherwise we're just ossifying the design that there's > just one archive module active at a time. > > >> I went ahead and removed the shutdown callback from basic_archive and the >> note about leaking from the documentation. > > -1 Okay. I've added it back in v12 with the suggested adjustment for the memory context stuff. -- Nathan Bossart Amazon Web Services: https://aws.amazon.com
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