MIME-Version: 1.0
References: <CAA4eK1LGmZsevrqJra0V4O8oBU_eKyzm2VMpSAYQaDgC6n4fkA@mail.gmail.com>
 <CAFiTN-uhnJkrUsQByBHMK268T-GEx_D8DQ6b2T+aW6RiU75pbQ@mail.gmail.com>
 <OS0PR01MB571621ED532C2D7C3E01625894FB9@OS0PR01MB5716.jpnprd01.prod.outlook.com>
 <CAFiTN-t5+_zTf86EzgCwObs1ED-P_5Ab1KMw340d3oPY_+Cwpw@mail.gmail.com>
 <OS3PR01MB5718AE486227CE3ACB844C5E94F89@OS3PR01MB5718.jpnprd01.prod.outlook.com>
 <CAFiTN-sgQ-K9BnMWKLR7Hm36QNjS7ZOBF6hsXJmQz5ChC0Desw@mail.gmail.com>
 <CAA4eK1+P9WOFBupaTZCzYtranSH=8TSUYV=kk5xQJ-VNKnvgmQ@mail.gmail.com>
 <OS0PR01MB571685A645E509267AC5F30894F99@OS0PR01MB5716.jpnprd01.prod.outlook.com>
 <OS0PR01MB57168A5A1C31BC316CB63D3C94F99@OS0PR01MB5716.jpnprd01.prod.outlook.com>
 <CAA4eK1KK7Xty7SaCReY_b5moPURowMGOsfvhOb6xQ1EAaJAh6A@mail.gmail.com>
 <OS0PR01MB5716863B23DBAD186F64ADF194FF9@OS0PR01MB5716.jpnprd01.prod.outlook.com>
 <CAHut+PvA10Bp9Jaw9OS2+puKHr7ry_xB3Tf2-bbv5gyxD5E_gw@mail.gmail.com>
 <CAA4eK1KYUbnthSPyo4VjnhMygB0c1DZtp0XC-V2-GSETQ743ww@mail.gmail.com>
 <CAJpy0uC0JamKT6pTtux3NDhcqSMJnDoQXZxx32pq=2yyxQ1c5Q@mail.gmail.com>
 <CAA4eK1KueUT_vr1cg43MpvRcaVvW03i6zDECQNAwFBK5PhXOVA@mail.gmail.com>
 <OS0PR01MB5716C663C85687E76672327094FD9@OS0PR01MB5716.jpnprd01.prod.outlook.com>
 <CAD21AoDBQ5hVi4hLmiU1D1JTMWtdj9NU5N4__c9Aqs8tUp0dsQ@mail.gmail.com>
 <OS0PR01MB5716C9F2C77BD3E403A713A994C29@OS0PR01MB5716.jpnprd01.prod.outlook.com>
 <CAA4eK1LA4k6=Z6cR-4b8uBT8dbE6yUS+c=0z9EiCAqOkL3S1BA@mail.gmail.com>
 <CAHut+PvFybTRJp24DdtcHF2QoG0OTfGsypa++drUW+yntPccjQ@mail.gmail.com>
 <CAA4eK1JA-=pSNmeCsjegnQBb00Q3U4ZovGbfHqK_V7R527QMQQ@mail.gmail.com>
 <CAHut+Psy9djSojhME3T_JjOQJsGiW-921Ruz7h2w1CTTMggg0Q@mail.gmail.com>
 <OS0PR01MB57169827FA43D15B5D2A4B0394C69@OS0PR01MB5716.jpnprd01.prod.outlook.com>
 <CAHut+Ptgj=DY8F1cMBRUxsZtq2-faW==5-dSuHSPJGx1a_vBFQ@mail.gmail.com> <OS0PR01MB57169845E9A6DEF86A7D682D94C69@OS0PR01MB5716.jpnprd01.prod.outlook.com>
In-Reply-To: <OS0PR01MB57169845E9A6DEF86A7D682D94C69@OS0PR01MB5716.jpnprd01.prod.outlook.com>
From: shveta malik <shveta.malik@gmail.com>
Date: Tue, 17 Jan 2023 10:03:30 +0530
Message-ID: <CAJpy0uC-_5gdVgp_1jyU_1PWZNCtq9P6RjtpsArejiN_Dku-sg@mail.gmail.com>
Subject: Re: Perform streaming logical transactions by background workers and
 parallel apply
To: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>
Cc: Peter Smith <smithpb2250@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, 
	"wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>, "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, 
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Dilip Kumar <dilipbalaut@gmail.com>, 
	Amit Kapila <amit.kapila16@gmail.com>, shveta malik <shveta.malik@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Archived-At: <https://www.postgresql.org/message-id/CAJpy0uC-_5gdVgp_1jyU_1PWZNCtq9P6RjtpsArejiN_Dku-sg%40mail.gmail.com>
Precedence: bulk

On Tue, Jan 17, 2023 at 9:07 AM houzj.fnst@fujitsu.com
<houzj.fnst@fujitsu.com> wrote:
>
> On Tuesday, January 17, 2023 11:32 AM Peter Smith <smithpb2250@gmail.com> wrote:
> >
> > On Tue, Jan 17, 2023 at 1:21 PM houzj.fnst@fujitsu.com
> > <houzj.fnst@fujitsu.com> wrote:
> > >
> > > On Tuesday, January 17, 2023 5:43 AM Peter Smith
> > <smithpb2250@gmail.com> wrote:
> > > >
> > > > On Mon, Jan 16, 2023 at 5:41 PM Amit Kapila
> > > > <amit.kapila16@gmail.com>
> > > > wrote:
> > > > >
> > > > > On Mon, Jan 16, 2023 at 10:24 AM Peter Smith
> > > > > <smithpb2250@gmail.com>
> > > > wrote:
> > > > > >
> > > > > > 2.
> > > > > >
> > > > > >  /*
> > > > > > + * Return the pid of the leader apply worker if the given pid
> > > > > > +is the pid of a
> > > > > > + * parallel apply worker, otherwise return InvalidPid.
> > > > > > + */
> > > > > > +pid_t
> > > > > > +GetLeaderApplyWorkerPid(pid_t pid) {  int leader_pid =
> > > > > > +InvalidPid;  int i;
> > > > > > +
> > > > > > + LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
> > > > > > +
> > > > > > + for (i = 0; i < max_logical_replication_workers; i++) {
> > > > > > + LogicalRepWorker *w = &LogicalRepCtx->workers[i];
> > > > > > +
> > > > > > + if (isParallelApplyWorker(w) && w->proc && pid ==
> > > > > > + w->proc->pid) { leader_pid = w->leader_pid; break; } }
> > > > > > +
> > > > > > + LWLockRelease(LogicalRepWorkerLock);
> > > > > > +
> > > > > > + return leader_pid;
> > > > > > +}
> > > > > >
> > > > > > 2a.
> > > > > > IIUC the IsParallelApplyWorker macro does nothing except check
> > > > > > that the leader_pid is not InvalidPid anyway, so AFAIK this
> > > > > > algorithm does not benefit from using this macro because we will
> > > > > > want to return InvalidPid anyway if the given pid matches.
> > > > > >
> > > > > > So the inner condition can just say:
> > > > > >
> > > > > > if (w->proc && w->proc->pid == pid) { leader_pid =
> > > > > > w->leader_pid; break; }
> > > > > >
> > > > >
> > > > > Yeah, this should also work but I feel the current one is explicit
> > > > > and more clear.
> > > >
> > > > OK.
> > > >
> > > > But, I have one last comment about this function -- I saw there are
> > > > already other functions that iterate max_logical_replication_workers
> > > > like this looking for things:
> > > > - logicalrep_worker_find
> > > > - logicalrep_workers_find
> > > > - logicalrep_worker_launch
> > > > - logicalrep_sync_worker_count
> > > >
> > > > So I felt this new function (currently called
> > > > GetLeaderApplyWorkerPid) ought to be named similarly to those ones.
> > > > e.g. call it something like "logicalrep_worker_find_pa_leader_pid".
> > > >
> > >
> > > I am not sure we can use the name, because currently all the API name
> > > in launcher that used by other module(not related to subscription) are
> > > like AxxBxx style(see the functions in logicallauncher.h).
> > > logicalrep_worker_xxx style functions are currently only declared in
> > > worker_internal.h.
> > >
> >
> > OK. I didn't know there was another header convention that you were following.
> > In that case, it is fine to leave the name as-is.
>
> Thanks for confirming!
>
> Attach the new version 0001 patch which addressed all other comments.
>
> Best regards,
> Hou zj

Hello Hou-san,

1. Do we need to extend test-cases to review the leader_pid column in
pg_stats tables?
2. Do we need to follow the naming convention for
'GetLeaderApplyWorkerPid' like other functions in the same file which
starts with 'logicalrep_'

thanks
Shveta