Adjust tuplestore.c not to allocate BufFiles in generation context

david-rowley · david-rowley · commit 04bcf9e19a42 · 2024-07-06T17:40:05.000+12:00
590b045 made it so tuplestore.c would store tuples inside a generation.c memory context. After fixing a bug report in 97651b0, it seems that it's probably best not to allocate BufFile related allocations in that context. Let's keep it just for tuple data. This adjusts the code to switch to the Tuplestorestate.context's parent, which is the MemoryContext that tuplestore_begin_common() was called in. It does not seem worth adding a new field in Tuplestorestate to store this when we can access it by looking at the Tuplestorestate's context's parent. Discussion: https://postgr.es/m/CAApHDvqFt_CdJtSr+E9YLZb7jZAyRCy3hjQ+ktM+dcOFVq-xkg@mail.gmail.com
diff --git a/src/backend/utils/sort/tuplestore.c b/src/backend/utils/sort/tuplestore.c
@@ -799,6 +799,7 @@ tuplestore_puttuple_common(Tuplestorestate *state, void *tuple)
 	TSReadPointer *readptr;
 	int			i;
 	ResourceOwner oldowner;
+	MemoryContext oldcxt;
 
 	state->tuples++;
 
@@ -850,8 +851,17 @@ tuplestore_puttuple_common(Tuplestorestate *state, void *tuple)
 			oldowner = CurrentResourceOwner;
 			CurrentResourceOwner = state->resowner;
 
+			/*
+			 * We switch out of the state->context as this is a generation
+			 * context, which isn't ideal for allocations relating to the
+			 * BufFile.
+			 */
+			oldcxt = MemoryContextSwitchTo(state->context->parent);
+
 			state->myfile = BufFileCreateTemp(state->interXact);
 
+			MemoryContextSwitchTo(oldcxt);
+
 			CurrentResourceOwner = oldowner;
 
 			/*
