Re: [HACKERS] Parallel tuplesort (for parallel B-Tree index creation)

From: Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>
To: Peter Geoghegan <pg(at)bowt(dot)ie>
Cc: Rushabh Lathia <rushabh(dot)lathia(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Corey Huinker <corey(dot)huinker(at)gmail(dot)com>
Subject: Re: [HACKERS] Parallel tuplesort (for parallel B-Tree index creation)
Date: 2017-12-08 02:03:50
Message-ID: CAEepm=2GE3vFkgzDsHcubOjE7DQLSjWLy_R315bD0u3yKvUWeQ@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox
Thread:
Lists: pgsql-hackers

On Fri, Dec 8, 2017 at 2:23 PM, Thomas Munro
<thomas(dot)munro(at)enterprisedb(dot)com> wrote:
> On Fri, Dec 8, 2017 at 1:57 PM, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
>> 1. Thomas' barrier abstraction was added by commit 1145acc7. I think
>> that you should use a static barrier in tuplesort.c now, and rip out
>> the ConditionVariable fields in the Sharedsort struct.
>
> ... So I think we'd need to add an extra barrier
> function that lets you change the party size of a static barrier.

Something like the attached (untested), which would allow
_bt_begin_parallel() to call BarrierInit(&barrier, request + 1), then
BarrierForgetParticipants(&barrier, request -
pcxt->nworkers_launched), and then all the condition variable loop
stuff can be replaced with a well placed call to
BarrierArriveAndWait(&barrier, WAIT_EVENT_SOMETHING_SOMETHING).

--
Thomas Munro
http://www.enterprisedb.com

Attachment Content-Type Size
barrier-forget-participants-v1.patch application/octet-stream 2.6 KB

In response to

Browse pgsql-hackers by date

  From Date Subject
Next Message Michael Paquier 2017-12-08 02:08:12 Re: PostgreSQL crashes with SIGSEGV
Previous Message Thomas Munro 2017-12-08 01:23:19 Re: [HACKERS] Parallel tuplesort (for parallel B-Tree index creation)