Re: [HACKERS] Restricting maximum keep segments by repslots

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>
Cc: jgdr(at)dalibo(dot)com, andres(at)anarazel(dot)de, michael(at)paquier(dot)xyz, sawada(dot)mshk(at)gmail(dot)com, peter(dot)eisentraut(at)2ndquadrant(dot)com, pgsql-hackers(at)lists(dot)postgresql(dot)org, thomas(dot)munro(at)enterprisedb(dot)com, sk(at)zsrv(dot)org, michael(dot)paquier(at)gmail(dot)com
Subject: Re: [HACKERS] Restricting maximum keep segments by repslots
Date: 2020-04-06 23:51:48
Message-ID: 20200406235148.GA29998@alvherre.pgsql
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On 2020-Apr-06, Alvaro Herrera wrote:

> I think there's a race condition in this: if we kill a walsender and it
> restarts immediately before we (checkpoint) can acquire the slot, we
> will wait for it to terminate on its own. Fixing this requires changing
> the ReplicationSlotAcquire API so that it knows not to wait but not
> raise error either (so we can use an infinite loop: "acquire, if busy
> send signal")

I think this should do it, but I didn't test it super-carefully and the
usage of the condition variable is not entirely kosher.

Álvaro Herrera
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Attachment Content-Type Size
v25delta-walsender-kill-loop.patch text/x-diff 6.1 KB

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