Re: Add client connection check during the execution of the query

On Fri, Jul 5, 2019 at 6:28 PM Tatsuo Ishii <ishii@sraoss.co.jp> wrote:
> > The purpose of this patch is to stop the execution of continuous
> > requests in case of a disconnection from the client.
>
> Pgpool-II already does this by sending a parameter status message to
> the client. It is expected that clients are always prepared to receive
> the parameter status message. This way I believe we could reliably
> detect that the connection to the client is broken or not.

Hmm.  If you send a message, it's basically application-level
keepalive.  But it's a lot harder to be sure that the protocol and
socket are in the right state to insert a message at every possible
CHECK_FOR_INTERRUPT() location.  Sergey's proposal of recv(MSG_PEEK)
doesn't require any knowledge of the protocol at all, though it
probably does need TCP keepalive to be configured to be useful for
remote connections.

-- 
Thomas Munro
https://enterprisedb.com