Feedback-ID: id4a34324:Fastmail
Date: Tue, 6 Dec 2022 10:32:44 -0800
From: Andres Freund <andres@anarazel.de>
To: Reid Thompson <reid.thompson@crunchydata.com>
Cc: Arne Roland <A.Roland@index.de>,
	"pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>,
	Justin Pryzby <pryzby@telsasoft.com>,
	Ibrar Ahmed <ibrar.ahmad@gmail.com>
Subject: Re: Add the ability to limit the amount of memory that can be
 allocated to backends.
Message-ID: <20221206183244.howaxkwg4tm4bnkp@awork3.anarazel.de>
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 <ee9486a314a341ec878fd61deadd9d3a@index.de>
 <f05c3d8aedc3fad650c15e2139cdd5e55683f0f5.camel@crunchydata.com>
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Hi,

On 2022-11-26 22:22:15 -0500, Reid Thompson wrote:
> rebased/patched to current master && current pg-stat-activity-backend-memory-allocated

This version fails to build with msvc, and builds with warnings on other
platforms.
https://cirrus-ci.com/build/5410696721072128
msvc:
[20:26:51.286] c:\cirrus\src\include\utils/backend_status.h(40): error C2059: syntax error: 'constant'

mingw cross:
[20:26:26.358]                  from /usr/share/mingw-w64/include/winsock2.h:23,
[20:26:26.358]                  from ../../src/include/port/win32_port.h:60,
[20:26:26.358]                  from ../../src/include/port.h:24,
[20:26:26.358]                  from ../../src/include/c.h:1306,
[20:26:26.358]                  from ../../src/include/postgres.h:47,
[20:26:26.358]                  from controldata_utils.c:18:
[20:26:26.358] ../../src/include/utils/backend_status.h:40:2: error: expected identifier before numeric constant
[20:26:26.358]    40 |  IGNORE,
[20:26:26.358]       |  ^~~~~~
[20:26:26.358] In file included from ../../src/include/postgres.h:48,
[20:26:26.358]                  from controldata_utils.c:18:
[20:26:26.358] ../../src/include/utils/backend_status.h: In function ‘pgstat_report_allocated_bytes’:
[20:26:26.358] ../../src/include/utils/backend_status.h:365:12: error: format ‘%ld’ expects argument of type ‘long int’, but argument 3 has type ‘uint64’ {aka ‘long long unsigned int’} [-Werror=format=]
[20:26:26.358]   365 |     errmsg("Backend %d deallocated %ld bytes, exceeding the %ld bytes it is currently reporting allocated. Setting reported to 0.",
[20:26:26.358]       |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[20:26:26.358]   366 |         MyProcPid, allocated_bytes, *my_allocated_bytes));
[20:26:26.358]       |                    ~~~~~~~~~~~~~~~
[20:26:26.358]       |                    |
[20:26:26.358]       |                    uint64 {aka long long unsigned int}

Due to windows having long be 32bit, you need to use %lld. Our custom to deal
with that is to cast the argument to errmsg as long long unsigned and use
%llu.

Btw, given that the argument is uint64, it doesn't seem correct to use %ld,
that's signed. Not that it's going to matter, but ...

Greetings,

Andres Freund