Re: [HACKERS] make async slave to wait for lsn to be replayed

On Fri, 8 Dec 2023 at 15:17, Kartyshov Ivan <i(dot)kartyshov(at)postgrespro(dot)ru> wrote:
>
> Should rise disscusion on separate utility statement or find
> case where procedure version is failed.
>
> 1) Classic (wait_classic_v3.patch)
> https://www.postgresql.org/message-id/3cc883048264c2e9af022033925ff8db%40postgrespro.ru
> ==========
> advantages: multiple wait events, separate WAIT FOR statement
> disadvantages: new words in grammar
>
>
>
> WAIT FOR [ANY | ALL] event [, ...]
> BEGIN [ WORK | TRANSACTION ] [ transaction_mode [, ...] ]
> [ WAIT FOR [ANY | ALL] event [, ...]]
> event:
> LSN value
> TIMEOUT number_of_milliseconds
> timestamp
>
>
>
> 2) After style: Kyotaro and Freund (wait_after_within_v2.patch)
> https://www.postgresql.org/message-id/d3ff2e363af60b345f82396992595a03%40postgrespro.ru
> ==========
> advantages: no new words in grammar
> disadvantages: a little harder to understand
>
>
>
> AFTER lsn_event [ WITHIN delay_milliseconds ] [, ...]
> BEGIN [ WORK | TRANSACTION ] [ transaction_mode [, ...] ]
> [ AFTER lsn_event [ WITHIN delay_milliseconds ]]
> START [ WORK | TRANSACTION ] [ transaction_mode [, ...] ]
> [ AFTER lsn_event [ WITHIN delay_milliseconds ]]
>
>
>
> 3) Procedure style: Tom Lane and Kyotaro (wait_proc_v7.patch)
> https://www.postgresql.org/message-id/27171.1586439221%40sss.pgh.pa.us
> https://www.postgresql.org/message-id/20210121.173009.235021120161403875.horikyota.ntt%40gmail.com
> ==========
> advantages: no new words in grammar,like it made in
> pg_last_wal_replay_lsn
> disadvantages: use snapshot xmin trick
> SELECT pg_waitlsn(‘LSN’, timeout);
> SELECT pg_waitlsn_infinite(‘LSN’);
> SELECT pg_waitlsn_no_wait(‘LSN’);

Few of the tests have aborted at [1] in CFBot with:
0000058`9c7ff550 00007ff6`5bdff1f4
postgres!pg_atomic_compare_exchange_u64_impl(
struct pg_atomic_uint64 * ptr = 0x00000000`00000008,
unsigned int64 * expected = 0x00000058`9c7ff5a0,
unsigned int64 newval = 0)+0x34
[c:\cirrus\src\include\port\atomics\generic-msvc.h @ 83]
00000058`9c7ff580 00007ff6`5bdff256 postgres!pg_atomic_read_u64_impl(
struct pg_atomic_uint64 * ptr = 0x00000000`00000008)+0x24
[c:\cirrus\src\include\port\atomics\generic.h @ 323]
00000058`9c7ff5c0 00007ff6`5bdfef67 postgres!pg_atomic_read_u64(
struct pg_atomic_uint64 * ptr = 0x00000000`00000008)+0x46
[c:\cirrus\src\include\port\atomics.h @ 430]
00000058`9c7ff5f0 00007ff6`5bc98fc3
postgres!GetMinWaitedLSN(void)+0x17
[c:\cirrus\src\backend\commands\wait.c @ 176]
00000058`9c7ff620 00007ff6`5bc82fb9
postgres!PerformWalRecovery(void)+0x4c3
[c:\cirrus\src\backend\access\transam\xlogrecovery.c @ 1788]
00000058`9c7ff6e0 00007ff6`5bffc651
postgres!StartupXLOG(void)+0x989
[c:\cirrus\src\backend\access\transam\xlog.c @ 5562]
00000058`9c7ff870 00007ff6`5bfed38b
postgres!StartupProcessMain(void)+0xd1
[c:\cirrus\src\backend\postmaster\startup.c @ 288]
00000058`9c7ff8a0 00007ff6`5bff49fd postgres!AuxiliaryProcessMain(
AuxProcType auxtype = StartupProcess (0n0))+0x1fb
[c:\cirrus\src\backend\postmaster\auxprocess.c @ 139]
00000058`9c7ff8e0 00007ff6`5beb7674 postgres!SubPostmasterMain(

More details are available at [2].

[1] - https://cirrus-ci.com/task/5618308515364864
[2] - https://api.cirrus-ci.com/v1/artifact/task/5618308515364864/crashlog/crashlog-postgres.exe_0008_2023-12-08_07-48-37-722.txt

Regards,
Vignesh