| From: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Timeout and wait-forever in sync rep |
| Date: | 2010-10-18 07:03:50 |
| Message-ID: | AANLkTing6ncNwRZdNjvgH0exxHB5=C+E-h7JrBxdcrTv@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sat, Oct 16, 2010 at 12:43 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> But they cannot
>> detect the disconnection in some cases. So replication_timeout needs
>> to be introduced for sync rep.
>
> When exactly don't the keepalives work?
The keepalives don't work at least on linux when the connection is terminated
after sending a packet and before receiving TCP-level ACK. You can confirm
this by unplugging the LAN cable from a client server while running pgbench
on a client. In this case, even if you specify tcp_keepalives_*, backends
would not be able to detect the disconnection. But note that this doesn't
always happen. Which depends on the timing.
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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