Re: [Bug] Usage of stale dead_items pointer in parallel vacuum

On Thu, Oct 2, 2025 at 12:56 AM Kevin Oommen Anish <kevin(dot)o(at)zohocorp(dot)com> wrote:
> Failed regression:
> CREATE TABLE pvactst2 (i INT) WITH (autovacuum_enabled = off);
> INSERT INTO pvactst2 SELECT generate_series(1, 1000);
> CREATE INDEX ON pvactst2 (i);
> CREATE INDEX ON pvactst2 (i);
> SET min_parallel_index_scan_size to 0;
> SET maintenance_work_mem TO 64;
> INSERT INTO pvactst2 SELECT generate_series(1, 1000);
> DELETE FROM pvactst2 WHERE i < 1000;
> VACUUM (PARALLEL 2) pvactst2;

I can reproduce the issue and confirm that your patch fixes it. I
didn't use your custom malloc allocator but instead applied a
redundant palloc0 for TidStore in TidStoreCreateShared(), hoping to
get a different chunk of memory (haha).

@@ -212,6 +212,7 @@ TidStoreCreateShared(size_t max_bytes, int tranche_id)
size_t dsa_init_size = DSA_DEFAULT_INIT_SEGMENT_SIZE;
size_t dsa_max_size = DSA_MAX_SEGMENT_SIZE;

+ ts = palloc0(sizeof(TidStore));
ts = palloc0(sizeof(TidStore));

- Richard