Обсуждение: Re: [COMMITTERS] pgsql: Improve memory management for external sorts.

On Fri, Mar 18, 2016 at 2:25 PM, Andres Freund <andres@anarazel.de> wrote:
> On 2016-03-17 20:11:00 +0000, Robert Haas wrote:
>> Improve memory management for external sorts.
>>
>> Introduce a new memory context which stores tuple data, and reset it
>> at the end of each merge pass; this helps avoid memory fragmentation
>> and, consequently, overallocation.  Also, for the final merge patch,
>> eliminate memory context chunk header overhead entirely by allocating
>> all of the memory used for buffering tuples during the merge in a
>> single chunk.  Since this modestly increases the number of tuples we
>> can store, grow the memtuples array a bit so that we're less likely to
>> run short of slots there.
>>
>> Peter Geoghegan.  Review and testing of patches in this series by
>> Jeff Janes, Greg Stark, Mithun Cy, and me.
>
> Cross compiling for windows results in:
> /home/andres/src/postgresql/src/backend/utils/sort/tuplesort.c: In function ‘beginmerge’:
> /home/andres/src/postgresql/src/backend/utils/sort/tuplesort.c:2695:34: warning: format ‘%ld’ expects argument of
type‘long int’, but argument 4 has type ‘int64 {aka long long int}’ [-Wformat=] 
>      elog(LOG, "tape %d initially used %ld KB of %ld KB batch "
>                                   ^
> /home/andres/src/postgresql/src/backend/utils/sort/tuplesort.c:2695:34: warning: format ‘%ld’ expects argument of
type‘long int’, but argument 5 has type ‘int64 {aka long long int}’ [-Wformat=] 
> config.status: creating src/interfaces/ecpg/include/ecpg_config.h
>
> /home/andres/src/postgresql/src/backend/utils/sort/tuplesort.c: In
> function ‘beginmerge’:
> /home/andres/src/postgresql/src/backend/utils/sort/tuplesort.c:2695:34:
> warning: format ‘%ld’ expects argument of type ‘long int’, but argument
> 4 has type ‘int64 {aka long long int}’ [-Wformat=]
>      elog(LOG, "tape %d initially used %ld KB of %ld KB batch "
>
> Which seems like a valid complain on a LLP64 platform (i.e. where long
> is 32bit) like windows.

Oops.  Thanks for the report.  Does this fix it?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

On Fri, Mar 18, 2016 at 2:39 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Fri, Mar 18, 2016 at 2:25 PM, Andres Freund <andres@anarazel.de> wrote:
>> On 2016-03-17 20:11:00 +0000, Robert Haas wrote:
>>> Improve memory management for external sorts.
>>>
>>> Introduce a new memory context which stores tuple data, and reset it
>>> at the end of each merge pass; this helps avoid memory fragmentation
>>> and, consequently, overallocation.  Also, for the final merge patch,
>>> eliminate memory context chunk header overhead entirely by allocating
>>> all of the memory used for buffering tuples during the merge in a
>>> single chunk.  Since this modestly increases the number of tuples we
>>> can store, grow the memtuples array a bit so that we're less likely to
>>> run short of slots there.
>>>
>>> Peter Geoghegan.  Review and testing of patches in this series by
>>> Jeff Janes, Greg Stark, Mithun Cy, and me.
>>
>> Cross compiling for windows results in:
>> /home/andres/src/postgresql/src/backend/utils/sort/tuplesort.c: In function ‘beginmerge’:
>> /home/andres/src/postgresql/src/backend/utils/sort/tuplesort.c:2695:34: warning: format ‘%ld’ expects argument of
type‘long int’, but argument 4 has type ‘int64 {aka long long int}’ [-Wformat=] 
>>      elog(LOG, "tape %d initially used %ld KB of %ld KB batch "
>>                                   ^
>> /home/andres/src/postgresql/src/backend/utils/sort/tuplesort.c:2695:34: warning: format ‘%ld’ expects argument of
type‘long int’, but argument 5 has type ‘int64 {aka long long int}’ [-Wformat=] 
>> config.status: creating src/interfaces/ecpg/include/ecpg_config.h
>>
>> /home/andres/src/postgresql/src/backend/utils/sort/tuplesort.c: In
>> function ‘beginmerge’:
>> /home/andres/src/postgresql/src/backend/utils/sort/tuplesort.c:2695:34:
>> warning: format ‘%ld’ expects argument of type ‘long int’, but argument
>> 4 has type ‘int64 {aka long long int}’ [-Wformat=]
>>      elog(LOG, "tape %d initially used %ld KB of %ld KB batch "
>>
>> Which seems like a valid complain on a LLP64 platform (i.e. where long
>> is 32bit) like windows.
>
> Oops.  Thanks for the report.  Does this fix it?

Trying again to attach the patch.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

On 2016-03-18 14:40:33 -0400, Robert Haas wrote:
> > Oops.  Thanks for the report.  Does this fix it?
> 
> Trying again to attach the patch.

Yes, that removes the warning, and looks correct.

Andres Freund

On Fri, Mar 18, 2016 at 11:43 AM, Andres Freund <andres@anarazel.de> wrote:
> Yes, that removes the warning, and looks correct.

Thanks. We should be careful to not repeat this mistake when the
quicksort patch goes in.


-- 
Peter Geoghegan

On Fri, Mar 18, 2016 at 4:22 PM, Peter Geoghegan <pg@heroku.com> wrote:
> On Fri, Mar 18, 2016 at 11:43 AM, Andres Freund <andres@anarazel.de> wrote:
>> Yes, that removes the warning, and looks correct.
>
> Thanks. We should be careful to not repeat this mistake when the
> quicksort patch goes in.

It would be helpful if you could either (a) confirm that that patch
still applies and that it has no issues of this type or (b) post an
updated version.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

On Sat, Mar 19, 2016 at 6:38 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> It would be helpful if you could either (a) confirm that that patch
> still applies and that it has no issues of this type or (b) post an
> updated version.

I don't think that it has a problem with lacking the right int64
format specifiers. However, I had a bad feeling about integer overflow
of state->currentRun, and think I'll need to address that. After all,
if runs are now no longer 2x work_mem on average, it's not completely
ridiculous to imagine that being an issue on a misconfigured system.

-- 
Peter Geoghegan