Message-ID: <b877e417-32c8-4864-b89e-cf6c66c1196d@vondra.me>
Date: Thu, 17 Jul 2025 23:14:52 +0200
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Subject: Re: Adding basic NUMA awareness
From: Tomas Vondra <tomas@vondra.me>
To: Jakub Wartak <jakub.wartak@enterprisedb.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
References: <099b9433-2855-4f1b-b421-d078a5d82017@vondra.me>
 <CAKZiRmy7VW5b0OKwHXtRSudCBFB48-kYnOEXeqrLfbTQ=5qQrA@mail.gmail.com>
 <c6493e5b-76c6-45a5-8067-3a36f4df4fe7@vondra.me>
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On 7/4/25 20:12, Tomas Vondra wrote:
> On 7/4/25 13:05, Jakub Wartak wrote:
>> ...
>>
>> 8. v1-0005 2x + /* if (numa_procs_interleave) */
>>
>>    Ha! it's a TRAP! I've uncommented it because I wanted to try it out
>> without it (just by setting GUC off) , but "MyProc->sema" is NULL :
>>
>>     2025-07-04 12:31:08.103 CEST [28754] LOG:  starting PostgreSQL
>> 19devel on x86_64-linux, compiled by gcc-12.2.0, 64-bit
>>     [..]
>>     2025-07-04 12:31:08.109 CEST [28754] LOG:  io worker (PID 28755)
>> was terminated by signal 11: Segmentation fault
>>     2025-07-04 12:31:08.109 CEST [28754] LOG:  terminating any other
>> active server processes
>>     2025-07-04 12:31:08.114 CEST [28754] LOG:  shutting down because
>> "restart_after_crash" is off
>>     2025-07-04 12:31:08.116 CEST [28754] LOG:  database system is shut down
>>
>>     [New LWP 28755]
>>     [Thread debugging using libthread_db enabled]
>>     Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
>>     Core was generated by `postgres: io worker                     '.
>>     Program terminated with signal SIGSEGV, Segmentation fault.
>>     #0  __new_sem_wait_fast (definitive_result=1, sem=sem@entry=0x0)
>> at ./nptl/sem_waitcommon.c:136
>>     136     ./nptl/sem_waitcommon.c: No such file or directory.
>>     (gdb) where
>>     #0  __new_sem_wait_fast (definitive_result=1, sem=sem@entry=0x0)
>> at ./nptl/sem_waitcommon.c:136
>>     #1  __new_sem_trywait (sem=sem@entry=0x0) at ./nptl/sem_wait.c:81
>>     #2  0x00005561918e0cac in PGSemaphoreReset (sema=0x0) at
>> ../src/backend/port/posix_sema.c:302
>>     #3  0x0000556191970553 in InitAuxiliaryProcess () at
>> ../src/backend/storage/lmgr/proc.c:992
>>     #4  0x00005561918e51a2 in AuxiliaryProcessMainCommon () at
>> ../src/backend/postmaster/auxprocess.c:65
>>     #5  0x0000556191940676 in IoWorkerMain (startup_data=<optimized
>> out>, startup_data_len=<optimized out>) at
>> ../src/backend/storage/aio/method_worker.c:393
>>     #6  0x00005561918e8163 in postmaster_child_launch
>> (child_type=child_type@entry=B_IO_WORKER, child_slot=20086,
>> startup_data=startup_data@entry=0x0,
>>         startup_data_len=startup_data_len@entry=0,
>> client_sock=client_sock@entry=0x0) at
>> ../src/backend/postmaster/launch_backend.c:290
>>     #7  0x00005561918ea09a in StartChildProcess
>> (type=type@entry=B_IO_WORKER) at
>> ../src/backend/postmaster/postmaster.c:3973
>>     #8  0x00005561918ea308 in maybe_adjust_io_workers () at
>> ../src/backend/postmaster/postmaster.c:4404
>>     [..]
>>     (gdb) print *MyProc->sem
>>     Cannot access memory at address 0x0
>>
> 
> Yeah, good catch. I'll look into that next week.
> 

I've been unable to reproduce this issue, but I'm not sure what settings
you actually used for this instance. Can you give me more details how to
reproduce this?

regards

-- 
Tomas Vondra