Re: Support for N synchronous standby servers - take 2

From: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
To: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Thom Brown <thom(at)linux(dot)com>, Beena Emerson <memissemerson(at)gmail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Support for N synchronous standby servers - take 2
Date: 2016-04-11 08:52:24
Message-ID: CAD21AoBqft7H3fVJJP3tkXL4GVkyUeyFVLUwdKHmh7vCCYH4vA@mail.gmail.com
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On Mon, Apr 11, 2016 at 1:31 PM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> On Mon, Apr 11, 2016 at 10:58 AM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>> On Sat, Apr 9, 2016 at 12:32 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:
>>>> When I compile now without cassert, I get the compiler warning:
>>>
>>>> syncrep.c: In function 'SyncRepUpdateConfig':
>>>> syncrep.c:878:6: warning: variable 'parse_rc' set but not used
>>>> [-Wunused-but-set-variable]
>>>
>>> If there's a good reason for that to be an Assert, I don't see it.
>>> There are no callers of SyncRepUpdateConfig that look like they
>>> need to, or should expect not to have to, tolerate errors.
>>> I think the way to fix this is to turn the Assert into a plain
>>> old test-and-ereport-ERROR.
>>>
>>
>> I've changed the draft patch Amit implemented so that it doesn't parse
>> twice(check_hook and assign_hook).
>> So assertion that was in assign_hook is no longer necessary.
>>
>> Please find attached.
>
> Thanks for the patch!
>
> When I emptied s_s_names, reloaded the configration file, set it to 'standby1'
> and reloaded the configuration file again, the master crashed with
> the following error.
>
> *** glibc detected *** postgres: wal sender process postgres [local]
> streaming 0/3015F18: munmap_chunk(): invalid pointer:
> 0x00000000024d9a40 ***
> ======= Backtrace: =========
> *** glibc detected *** postgres: wal sender process postgres [local]
> streaming 0/3015F18: munmap_chunk(): invalid pointer:
> 0x00000000024d9a40 ***
> /lib64/libc.so.6[0x3be8e75f4e]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x97dae2]
> ======= Backtrace: =========
> /lib64/libc.so.6[0x3be8e75f4e]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(set_config_option+0x12cb)[0x982242]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(SetConfigOption+0x4b)[0x9827ff]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x97dae2]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x988b4e]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(set_config_option+0x12cb)[0x982242]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x98af40]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(SetConfigOption+0x4b)[0x9827ff]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(ProcessConfigFile+0x9f)[0x98a98b]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x988b4e]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x98af40]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x7b50fd]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(ProcessConfigFile+0x9f)[0x98a98b]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x7b359c]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x7b50fd]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(exec_replication_command+0x1a7)[0x7b47b6]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x7b359c]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(PostgresMain+0x772)[0x8141b6]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(exec_replication_command+0x1a7)[0x7b47b6]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x7896f7]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(PostgresMain+0x772)[0x8141b6]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x788e62]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x7896f7]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x785544]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x788e62]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(PostmasterMain+0x1134)[0x784c08]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x785544]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x6ce12e]
> /lib64/libc.so.6(__libc_start_main+0xfd)[0x3be8e1ed5d]
> postgres: wal sender process postgres [local] streaming
> 0/3015F18(PostmasterMain+0x1134)[0x784c08]
> postgres: wal sender process postgres [local] streaming 0/3015F18[0x467e99]
>

Thank you for reviewing.

SyncRepUpdateConfig() seems to be no longer necessary.
Attached updated version.

Regards,

--
Masahiko Sawada

Attachment Content-Type Size
fix_sync_rep_update_conf_v3.patch text/x-patch 5.9 KB

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