From af72b0889441e5ece199f782511d84d72fa6b88c Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 12 Jul 2022 16:30:36 -0400 Subject: Invent qsort_interruptible(). Justin Pryzby reported that some scenarios could cause gathering of extended statistics to spend many seconds in an un-cancelable qsort() operation. To fix, invent qsort_interruptible(), which is just like qsort_arg() except that it will also do CHECK_FOR_INTERRUPTS every so often. This bloats the backend by a couple of kB, which seems like a good investment. (We considered just enabling CHECK_FOR_INTERRUPTS in the existing qsort and qsort_arg functions, but there are some callers for which that'd demonstrably be unsafe. Opt-in seems like a better way.) For now, just apply qsort_interruptible() in statistics collection. There's probably more places where it could be useful, but we can always change other call sites as we find problems. Back-patch to v14. Before that we didn't have extended stats on expressions, so that the problem was less severe. Also, this patch depends on the sort_template infrastructure introduced in v14. Tom Lane and Justin Pryzby Discussion: https://postgr.es/m/20220509000108.GQ28830@telsasoft.com --- src/backend/utils/sort/qsort_interruptible.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) create mode 100644 src/backend/utils/sort/qsort_interruptible.c (limited to 'src/backend/utils/sort/qsort_interruptible.c') diff --git a/src/backend/utils/sort/qsort_interruptible.c b/src/backend/utils/sort/qsort_interruptible.c new file mode 100644 index 00000000000..f179b256248 --- /dev/null +++ b/src/backend/utils/sort/qsort_interruptible.c @@ -0,0 +1,16 @@ +/* + * qsort_interruptible.c: qsort_arg that includes CHECK_FOR_INTERRUPTS + */ + +#include "postgres.h" +#include "miscadmin.h" + +#define ST_SORT qsort_interruptible +#define ST_ELEMENT_TYPE_VOID +#define ST_COMPARATOR_TYPE_NAME qsort_arg_comparator +#define ST_COMPARE_RUNTIME_POINTER +#define ST_COMPARE_ARG_TYPE void +#define ST_SCOPE +#define ST_DEFINE +#define ST_CHECK_FOR_INTERRUPTS +#include "lib/sort_template.h" -- cgit v1.2.3