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Date: Wed, 10 Jul 2024 07:58:23 +0300
From: Kartyshov Ivan <i.kartyshov@postgrespro.ru>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: aekorotkov@gmail.com, hlinnaka@iki.fi, alvherre@alvh.no-ip.org,
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Subject: Re: [HACKERS] make async slave to wait for lsn to be replayed
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>> I think the race condition you mentioned refers to the inconsistency
>> between the inHeap flag and the pairing heap caused by a race
>> condition between timeout and wakeup (or perhaps other combinations?
>> I'm not sure which version of the patch the mentioned race condition
>> refers to). However, I imagine it is difficult to reliably reproduce
>> this condition. In that regard, in the latest patch, the coherence
>> between the inHeap flag and the pairing heap is protected by LWLock,
>> so I believe we no longer need that test.
> 
> No, Alexandre means that Heikki point on race condition just before
> LWLock. But injection point we can inject and stepin on backend, and
> WaitLSNSetLatches is used from Recovery process. But I have trouble
> to wakeup injection point on server.

One more thing. I want to point, when you move injection point to
contrib dir and do the same test (044_wal_replay_wait_injection_test.pl)
step by step with hands, wakeup works well.

-- 
Ivan Kartyshov
Postgres Professional: www.postgrespro.com