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authorNoah Misch <noah@leadboat.com>2024-09-17 19:53:11 -0700
committerNoah Misch <noah@leadboat.com>2024-09-17 19:54:26 -0700
commit507b72bd9f7de95a224ae5af8797f42bfce1ed9c (patch)
tree949db3287d2bc0cda064b7763b3d013d3215339e /src/backend/optimizer/plan/planner.c
parent011659d498357f4c0f243816140b09085422d309 (diff)
Don't enter parallel mode when holding interrupts.
Doing so caused the leader to hang in wait_event=ParallelFinish, which required an immediate shutdown to resolve. Back-patch to v12 (all supported versions). Francesco Degrassi Discussion: https://postgr.es/m/CAC-SaSzHUKT=vZJ8MPxYdC_URPfax+yoA1hKTcF4ROz_Q6z0_Q@mail.gmail.com
Diffstat (limited to 'src/backend/optimizer/plan/planner.c')
-rw-r--r--src/backend/optimizer/plan/planner.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 65a9b0d802a..f7539fed6fb 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -331,6 +331,11 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
* general; updates and deletes have additional problems especially around
* combo CIDs.)
*
+ * We don't try to use parallel mode unless interruptible. The leader
+ * expects ProcessInterrupts() calls to reach HandleParallelMessages().
+ * Even if we called HandleParallelMessages() another way, starting a
+ * parallel worker is too delay-prone to be prudent when uncancellable.
+ *
* For now, we don't try to use parallel mode if we're running inside a
* parallel worker. We might eventually be able to relax this
* restriction, but for now it seems best not to have parallel workers
@@ -341,6 +346,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
parse->commandType == CMD_SELECT &&
!parse->hasModifyingCTE &&
max_parallel_workers_per_gather > 0 &&
+ INTERRUPTS_CAN_BE_PROCESSED() &&
!IsParallelWorker())
{
/* all the cheap tests pass, so scan the query tree */