From 6708e447efb5046c95bdcf900b6da97f56f97ae8 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 31 Aug 2017 15:10:24 -0400 Subject: Clean up shm_mq cleanup. The logic around shm_mq_detach was a few bricks shy of a load, because (contrary to the comments for shm_mq_attach) all it did was update the shared shm_mq state. That left us leaking a bit of process-local memory, but much worse, the on_dsm_detach callback for shm_mq_detach was still armed. That means that whenever we ultimately detach from the DSM segment, we'd run shm_mq_detach again for already-detached, possibly long-dead queues. This accidentally fails to fail today, because we only ever re-use a shm_mq's memory for another shm_mq, and multiple detach attempts on the last such shm_mq are fairly harmless. But it's gonna bite us someday, so let's clean it up. To do that, change shm_mq_detach's API so it takes a shm_mq_handle not the underlying shm_mq. This makes the callers simpler in most cases anyway. Also fix a few places in parallel.c that were just pfree'ing the handle structs rather than doing proper cleanup. Back-patch to v10 because of the risk that the revenant shm_mq_detach callbacks would cause a live bug sometime. Since this is an API change, it's too late to do it in 9.6. (We could make a variant patch that preserves API, but I'm not excited enough to do that.) Discussion: https://postgr.es/m/8670.1504192177@sss.pgh.pa.us --- src/include/storage/shm_mq.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'src/include') diff --git a/src/include/storage/shm_mq.h b/src/include/storage/shm_mq.h index 02a93e02222..7709efcc483 100644 --- a/src/include/storage/shm_mq.h +++ b/src/include/storage/shm_mq.h @@ -62,8 +62,8 @@ extern shm_mq_handle *shm_mq_attach(shm_mq *mq, dsm_segment *seg, /* Associate worker handle with shm_mq. */ extern void shm_mq_set_handle(shm_mq_handle *, BackgroundWorkerHandle *); -/* Break connection. */ -extern void shm_mq_detach(shm_mq *); +/* Break connection, release handle resources. */ +extern void shm_mq_detach(shm_mq_handle *mqh); /* Get the shm_mq from handle. */ extern shm_mq *shm_mq_get_queue(shm_mq_handle *mqh); -- cgit v1.2.3