Re: Fix pg_log_backend_memory_contexts() 's delay

On 2021/10/06 17:14, bt21tanigaway wrote:
> Thanks for your review.
>
>>> Thanks for the patch. Do we also need to do the change in
>>> HandleMainLoopInterrupts, HandleCheckpointerInterrupts,
>>> HandlePgArchInterrupts, HandleWalWriterInterrupts as we don't call
>>> CHECK_FOR_INTERRUPTS() there?
>
>> Yeah, that's still some information that the user asked for.  Looking
>> at the things that have a PGPROC entry, should we worry about the main
>> loop of the logical replication launcher?
>
> ・Now, the target of “pg_log_backend_memory_contexts()” is “autovacuum launcher” and “logical replication launcher”.  I observed that the delay occurred only in “autovacuum launcher” not in “logical replication launcher”.
> ・”autovacuum launcher” used “HandleAutoVacLauncherInterrupts()” ( not including “ProcessLogMemoryContextInterrupt()” ) instead of “ProcessInterrupts() ( including “ProcessLogMemoryContextInterrupt()” ). “ProcessLogMemoryContextInterrupt()” will not be executed until the next “ProcessInterrupts()” is executed. So, I added “ProcessLogMemoryContextInterrupt()”.
> ・”logical replication launcher” uses only “ProcessInterrupts()”. So, We don’t have to fix it.

Yes.

>> IMHO, we can support all the processes which return a PGPROC entry by
>> both BackendPidGetProc and AuxiliaryPidGetProc where the
>> AuxiliaryPidGetProc would cover the following processes. I'm not sure
>> one is interested in the  memory context info of auxiliary processes.

I like this idea because it seems helpful at least for debug purpose.

> ・The purpose of this patch is to solve the delay problem, so I would like another patch to deal with “ BackendPidGetProc” and “AuxiliaryPidGetProc”.

+1 to improve those things separately.

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION