Re: missing comment in lwlock.c

Hi,

On 2016-08-01 10:43:43 +0200, Jens.Wilke@parcIT.de wrote:
> there is no comment on "PANIC:  queueing for lock while waiting on another
> one" in lwlock.c

That's because it's not expected to be ever reached.


> Postgres Version is 9.5.3.
>
>     2016-07-25 18:32:54 CEST [45824]: [185-1]
> user=svc_sqlbalancer_worker,db=adr,client=::1 FATAL:  *semop(id=6389799)
> failed: Identifier removed*
>     2016-07-25 18:32:54 CEST [45824]: [186-1]
> user=svc_sqlbalancer_worker,db=adr,client=::1 CONTEXT:  SQL statement
> "create temp table ausfall_ereignis_tmp as
>     2016-07-25 18:32:54 CEST [45824]: [187-1]
> user=svc_sqlbalancer_worker,db=adr,client=::1 STATEMENT:  SELECT * FROM
> svc_sqlbalancer.fx_run_work(50119)
>     2016-07-25 18:32:54 CEST [45824]: [188-1]
> user=svc_sqlbalancer_worker,db=adr,client=::1 *PANIC:  queueing for lock
> while waiting on another one*
>
>     2016-07-25 18:32:55 CEST [12024]: [176-1] user=,db=,client= LOG:
> server process (PID 45824) was terminated by signal 6: Aborted
>     2016-07-25 18:33:16 CEST [12024]: [179-1] user=,db=,client= LOG:  all
> server processes terminated; reinitializing
>     2016-07-25 18:33:16 CEST [12024]: [180-1] user=,db=,client= LOG:  could
> not remove shared memory segment "/PostgreSQL.605661915": No such file or
> directory
>     2016-07-25 18:33:16 CEST [12024]: [181-1] user=,db=,client= LOG:
> semctl(5144577, 0, IPC_RMID, ...) failed: Invalid argument
>     2016-07-25 18:33:16 CEST [12024]: [182-1] user=,db=,client= LOG:
> semctl(5177346, 0, IPC_RMID, ...) failed: Invalid argument
>     2016-07-25 18:33:16 CEST [12024]: [183-1] user=,db=,client= LOG:
> semctl(5210115, 0, IPC_RMID, ...) failed: Invalid argument

This sounds like it's a consequence of sysv semaphores and shared memory
being removed while postgres is running. Any chance this was a postgres
running on a systemd machine with RemoveIPC=true?

Andres