From 5e6368b42ee6d4b59e085301ca7b0e50f37a897b Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Wed, 16 Mar 2022 13:37:58 +1300 Subject: Wake up for latches in CheckpointWriteDelay(). The checkpointer shouldn't ignore its latch. Other backends may be waiting for it to drain the request queue. Hopefully real systems don't have a full queue often, but the condition is reached easily when shared_buffers is small. This involves defining a new wait event, which will appear in the pg_stat_activity view often due to spread checkpoints. Back-patch only to 14. Even though the problem exists in earlier branches too, it's hard to hit there. In 14 we stopped using signal handlers for latches on Linux, *BSD and macOS, which were previously hiding this problem by interrupting the sleep (though not reliably, as the signal could arrive before the sleep begins; precisely the problem latches address). Reported-by: Andres Freund Reviewed-by: Andres Freund Discussion: https://postgr.es/m/20220226213942.nb7uvb2pamyu26dj%40alap3.anarazel.de --- src/backend/postmaster/checkpointer.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'src/backend/postmaster/checkpointer.c') diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c index 4488e3a4435..a59c3cf0201 100644 --- a/src/backend/postmaster/checkpointer.c +++ b/src/backend/postmaster/checkpointer.c @@ -484,6 +484,9 @@ CheckpointerMain(void) } ckpt_active = false; + + /* We may have received an interrupt during the checkpoint. */ + HandleCheckpointerInterrupts(); } /* Check for archive_timeout and switch xlog files if necessary. */ @@ -726,7 +729,10 @@ CheckpointWriteDelay(int flags, double progress) * Checkpointer and bgwriter are no longer related so take the Big * Sleep. */ - pg_usleep(100000L); + WaitLatch(MyLatch, WL_LATCH_SET | WL_EXIT_ON_PM_DEATH | WL_TIMEOUT, + 100, + WAIT_EVENT_CHECKPOINT_WRITE_DELAY); + ResetLatch(MyLatch); } else if (--absorb_counter <= 0) { -- cgit v1.2.3