Ni Nathan, On Thu, Sep 11, 2025 at 09:15:12PM +0000, Nathan Bossart wrote: > Move named LWLock tranche requests to shared memory. > > In EXEC_BACKEND builds, GetNamedLWLockTranche() can segfault when > called outside of the postmaster process, as it might access > NamedLWLockTrancheRequestArray, which won't be initialized. Given > the lack of reports, this is apparently unusual, presumably because > it is usually called from a shmem_startup_hook like this:
Since this commit has been merged, batta has kept failing. Here is the first failure: https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=batta&dt=2025-09-12%2002%3A05%3A01 I use this animal with a specific configuration: shared_preload_libraries = 'pg_stat_statements' compute_query_id = regress regress_dump_restore wal_consistency_checking --enable-injection-points The recovery tests 013_crash_restart.pl, 022_crash_temp_files.pl and 041_checkpoint_at_promote.pl stress some restart scenarios, not all use injection points. I could not get a backtrace from the host. However, I have come up with the following change in 013 that's able to reproduce what I think is the same crash: --- a/src/test/recovery/t/013_crash_restart.pl +++ b/src/test/recovery/t/013_crash_restart.pl @@ -21,6 +21,8 @@ my $psql_timeout = IPC::Run::timer($PostgreSQL::Test::Utils::timeout_default); my $node = PostgreSQL::Test::Cluster->new('primary'); $node->init(allows_streaming => 1); +$node->append_conf('postgresql.conf', + "shared_preload_libraries = 'pg_stat_statements'"); $node->start(); And here is the backtrace: #0 0x000055fcdf6bc97a in NumLWLocksForNamedTranches () at lwlock.c:385 385 numLocks += NamedLWLockTrancheRequestArray[i].num_lwlocks; (gdb) bt #0 0x000055fcdf6bc97a in NumLWLocksForNamedTranches () at lwlock.c:385 #1 0x000055fcdf6bc9b3 in LWLockShmemSize () at lwlock.c:400 #2 0x000055fcdf65bda5 in CalculateShmemSize (num_semaphores=0x7ffcaf7a78e4) at ipci.c:130 #3 0x000055fcdf65c0b1 in CreateSharedMemoryAndSemaphores () at ipci.c:210 #4 0x000055fcdf42830c in PostmasterStateMachine () at postmaster.c:3223 #5 0x000055fcdf42703f in process_pm_child_exit () at postmaster.c:2558 #6 0x000055fcdf425729 in ServerLoop () at postmaster.c:1696 #7 0x000055fcdf424be1 in PostmasterMain (argc=4, argv=0x55fd0a8faa10) at postmaster.c:1403 #8 0x000055fcdef80a19 in main (argc=4, argv=0x55fd0a8faa10) at main.c:231 (gdb) p i $3 = 0 (gdb) p NamedLWLockTrancheRequestArray[0] Cannot access memory at address 0x7f15ee4ccc08 Thanks, -- Michael
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