On Tue, Dec 10, 2024 at 1:16 AM Amit Kapila <amit.kapil...@gmail.com> wrote: > > On Tue, Dec 10, 2024 at 11:24 AM Amit Kapila <amit.kapil...@gmail.com> wrote: > > > > On Tue, Dec 10, 2024 at 8:54 AM vignesh C <vignes...@gmail.com> wrote: > > > > > > On Tue, 10 Dec 2024 at 04:56, Michael Paquier <mich...@paquier.xyz> wrote: > > > > > > > > On Mon, Dec 09, 2024 at 03:36:15PM +0530, Amit Kapila wrote: > > > > > It couldn't solve the problem completely even in back-branches. The > > > > > SQL API case I mentioned and tested by Hou-San in the email [1] won't > > > > > be solved. > > > > > > > > > > [1] - > > > > > https://www.postgresql.org/message-id/OS0PR01MB57166A4DA0ABBB94F2FBB28694362%40OS0PR01MB5716.jpnprd01.prod.outlook.com > > > > > > > > Yeah, exactly (wanted to reply exactly that yesterday but lacked time, > > > > thanks!). > > > > > > Yes, that makes sense. How about something like the attached patch. > > > > > > > - oldctx = MemoryContextSwitchTo(CacheMemoryContext); > > - if (data->publications) > > - { > > - list_free_deep(data->publications); > > - data->publications = NIL; > > - } > > + static MemoryContext pubctx = NULL; > > + > > + if (pubctx == NULL) > > + pubctx = AllocSetContextCreate(CacheMemoryContext, > > + "logical replication publication list context", > > + ALLOCSET_SMALL_SIZES); > > + else > > + MemoryContextReset(pubctx); > > + > > + oldctx = MemoryContextSwitchTo(pubctx); > > > > Considering the SQL API case, why is it okay to allocate this context > > under CacheMemoryContext? > > > > On further thinking, we can't allocate it under > LogicalDecodingContext->context because once that is freed at the end > of SQL API pg_logical_slot_get_changes(), pubctx will be pointing to a > dangling memory. One idea is that we use > MemoryContextRegisterResetCallback() to invoke a reset callback > function where we can reset pubctx but not sure if we want to go there > in back branches. OTOH, the currently proposed fix won't leak memory > on repeated calls to pg_logical_slot_get_changes(), so that might be > okay as well. > > Thoughts?
Alternative idea is to declare pubctx as a file static variable. And we create the memory context under LogicalDecodingContext->context in the startup callback and free it in the shutdown callback. Regards, -- Masahiko Sawada Amazon Web Services: https://aws.amazon.com
