From adca67867ff5f37ee8c97879a1ec5dc2bf0150f0 Mon Sep 17 00:00:00 2001 From: Shayon Mukherjee Date: Mon, 5 May 2025 15:32:41 -0400 Subject: [PATCH v18] Limit VACUUM truncation retries after scan interruption --- src/backend/access/heap/vacuumlazy.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c index f28326bad0..a91c1b97cb 100644 --- a/src/backend/access/heap/vacuumlazy.c +++ b/src/backend/access/heap/vacuumlazy.c @@ -179,6 +179,8 @@ #define VACUUM_TRUNCATE_LOCK_CHECK_INTERVAL 20 /* ms */ #define VACUUM_TRUNCATE_LOCK_WAIT_INTERVAL 50 /* ms */ #define VACUUM_TRUNCATE_LOCK_TIMEOUT 5000 /* ms */ +/* Max retries for the truncation attempt if the backward scan is interrupted */ +#define VACUUM_TRUNCATE_INTERRUPTION_MAX_RETRIES 3 /* * Threshold that controls whether we bypass index vacuuming and heap @@ -3213,6 +3215,7 @@ lazy_truncate_heap(LVRelState *vacrel) BlockNumber new_rel_pages; bool lock_waiter_detected; int lock_retry; + int truncate_interruption_retry_count = 0; /* Report that we are now truncating */ pgstat_progress_update_param(PROGRESS_VACUUM_PHASE, @@ -3227,6 +3230,19 @@ lazy_truncate_heap(LVRelState *vacrel) */ do { + /* + * Check if we've retried too many times due to interruptions. We + * check here to allow at least one full attempt even if + * max_truncate_retries is set low. + */ + if (truncate_interruption_retry_count >= VACUUM_TRUNCATE_INTERRUPTION_MAX_RETRIES) + { + ereport(vacrel->verbose ? INFO : DEBUG2, + (errmsg("table \"%s\": stopping truncate after %d retries due to repeated conflicting lock requests", + vacrel->relname, truncate_interruption_retry_count))); + break; + } + /* * We need full exclusive lock on the relation in order to do * truncation. If we can't get it, give up rather than waiting --- we @@ -3329,6 +3345,14 @@ lazy_truncate_heap(LVRelState *vacrel) vacrel->relname, orig_rel_pages, new_rel_pages))); orig_rel_pages = new_rel_pages; + + /* + * Increment retry count only if we were interrupted and will loop + * again + */ + if (lock_waiter_detected && new_rel_pages > vacrel->nonempty_pages) + truncate_interruption_retry_count++; + } while (new_rel_pages > vacrel->nonempty_pages && lock_waiter_detected); } -- 2.39.5 (Apple Git-154)