Re: Inconsistency in startup process's MyBackendId and procsignal array registration with ProcSignalInit()

On 2021/10/11 19:46, Bharath Rupireddy wrote:
> If we do the above, then the problem might arise if somebody calls
> SICleanupQueue and wants to signal the startup process, the below code
> (from SICleanupQueue) can't get the startup process backend id. So,
> the backend id calculation for the startup process can't just be
> MaxBackends + MyAuxProcType + 1.
> BackendId his_backendId = (needSig - &segP->procState[0]) + 1;

Attached POC patch illustrates what I'm in mind. ISTM this change
doesn't prevent SICleanupQueue() from getting right backend ID
of the startup process. Thought?


> It looks like we need to increase the size of the ProcState array by 1
> at least (for the startup process). Currently the ProcState array
> doesn't have entries for auxiliary processes, it does have entries for
> MaxBackends. The startup process is eating up one slot from
> MaxBackends. Since we need only an extra ProcState array slot for the
> startup process I think we could just extend its size by 1. Instead of
> modifying the MaxBackends definition, we can just add 1 (and a comment
> saying this 1 is for startup process) to  shmInvalBuffer->maxBackends
> in SInvalShmemSize, CreateSharedInvalidationState. IMO, this has to go
> in a separate patch and probably in a separate thread. Thoughts?

Agreed.

Regards,

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