Don't sleep with vacuum_delay_point() while holding locks It's a bad idea to sleep while holding locks, because you might block another process that wants to acquire the same lock. Furthermore, it's not safe to call ProcessConfigFile() in a critical section or while holding locks. So avoid calling vacuum_delay_point() while holding locks, and also make vacuum_delay_point() return quickly without sleeping if it's called while interrupts cannot be processed.
To find the vacuum_delay_point() calls that were made while holding locks, I added "Assert(INTERRUPTS_CAN_BE_PROCESSED())" in vacuum_delay_point() and ran the regression tests. I didn't include that Assert in this commit, because there might be more places that do that that are not covered by the regression tests, including extensions. In ginInsertCleanup(), there was already another vacuum_delay_point() call later in the loop, while not holding any locks, so just remove the other call that was made while holding the lock. In hashbucketcleanup(), move the vacuum_delay_point() call up the stack to its caller. The call in hashbucketcleanup() was not able to handle interrupts because it held a lock, and because there were no vacuum_delay_point() or CHECK_FOR_INTERRUPTS() calls in the caller's loop, the whole hash index vacuuming phase was uninterruptible by pending shutdown or query cancel. Now it can be interrupted between buckets. Unfortunately, hashbucketcleanup() has to process all the bucket's pages in one go without pausing; fixing that would require changing how hashbucketcleanup()'s lock chaining works. In acquire_sample_rows(), move the vacuum_delay_point() call in the loop to between pages, to a time where we're not holding the buffer lock. In master, also remove a misleading CHECK_FOR_INTERRUPTS() call from pgstat_write_statsfile(). It was a no-op because we're always holding a lock on the current dshash partition at that point. A call that does nothing is harmless, but it makes you think that the loop is interruptible when in reality it's not. Author: Kevin Rocker <[email protected]> Author: Andrey Borodin <[email protected]> Author: Mostafa <[email protected]> Reported-by: Greg Burd <[email protected]> Reported-by: Sergei Kornilov <[email protected]> Reviewed-by: Kirill Reshke <[email protected]> Reviewed-by: Neil Chen <[email protected]> Tested-by: Greg Burd <[email protected]> Discussion: https://postgr.es/m/[email protected] Discussion: https://postgr.es/m/492c6247-43d3-477b-8981-fb0c56767b38%40app.fastmail.com Backpatch-through: 14 Branch ------ REL_18_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/5f671c4312bb5addac4de4f329907a4681e81276 Modified Files -------------- src/backend/access/gin/ginfast.c | 6 +++--- src/backend/access/hash/hash.c | 5 +++-- src/backend/commands/analyze.c | 3 +-- src/backend/commands/vacuum.c | 8 ++++++++ 4 files changed, 15 insertions(+), 7 deletions(-)
