public inbox for [email protected]  

help / color / mirror / Atom feed

From: PG Bug reporting form <[email protected]>
To: [email protected]
Cc: [email protected]
Subject: BUG #19530: Crash (SIGSEGV/SIGBUS) in parallel B-tree index vacuum during plain VACUUM
Date: Sun, 21 Jun 2026 21:38:09 +0000
Message-ID: <[email protected]> (raw)

The following bug has been logged on the website:

Bug reference:      19530
Logged by:          Maciej
Email address:      [email protected]
PostgreSQL version: 17.7
Operating system:   FreeBSD 14.4-RELEASE, x86-64
Description:        

PostgreSQL 17.7 intermittently crashes a parallel maintenance worker during
routine VACUUM, taking the server through automatic crash recovery each
  time.

  Summary:
  Recurring backend / parallel-worker terminations with signal 11 (SIGSEGV)
and signal 10 (SIGBUS). Each crash is followed by "terminating any other
  active server processes" and crash recovery (~5 s). It is intermittent:
about 16 process terminations over 5 days, with fully clean days in between;
  the same nightly maintenance succeeds on most days. Hardware was checked
and is clean (no MCE/ECC/I/O errors).

  Environment:
  PostgreSQL 17.7, FreeBSD 14.4-RELEASE, x86-64, physical server, 256 GB
RAM. dynamic_shared_memory_type=posix, huge_pages=try.
  max_parallel_workers=8, max_parallel_maintenance_workers=4,
max_parallel_workers_per_gather=4. Extensions: pg_stat_statements, pg_trgm,
unaccent,
  plpgsql only — no custom C extensions, no PL/Perl/Python.

  What the crashing process was doing:
  The crashing process is a parallel maintenance worker. A preserved core
dump shows the process title "parallel worker for PID <leader>", with memory
  contexts "BTree Vacuum State" and "AutoVacuum Data" present and no
executor/query state — i.e. parallel index vacuum, not parallel query. The
  trigger is a scheduled VACUUM (SKIP_DATABASE_STATS, VERBOSE, ANALYZE) run
via vacuumdb over several large tables, each carrying many (~10–30) btree
  indexes, so parallel index vacuuming is engaged. The SIGBUS variant is
consistent with a DSM (POSIX shared memory) problem in the parallel path.

  Expected vs actual:
  Expected: VACUUM completes normally. Actual: a parallel index-vacuum
worker crashes (SIGSEGV/SIGBUS) and the server goes through crash recovery.

  Possibly related:
  This appears to reach the same btbulkdelete / btvacuumscan code as the
report "Segmentation fault in PostgreSQL 17.7 during REINDEX TABLE
  CONCURRENTLY"
(https://www.postgresql.org/message-id/[email protected]...),
but reached
  via the plain-VACUUM index-vacuum path rather than validate_index /
ReindexRelationConcurrently. That suggests the fault is in the (parallel)
B-tree
  index-vacuum code, reachable from both paths.

  Workaround:
  Setting max_parallel_maintenance_workers = 0 (sequential index vacuuming)
appears to stop the crashes (observation ongoing).

view thread (2+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected]
  Subject: Re: BUG #19530: Crash (SIGSEGV/SIGBUS) in parallel B-tree index vacuum during plain VACUUM
  In-Reply-To: <[email protected]>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox