Re: Supporting TCP_SYNCNT in libpq

Ciao Francesco,

On Mon, 17 Mar 2025 at 09:19, Francesco Canovai <
francesco(dot)canovai(at)enterprisedb(dot)com> wrote:

> This patch introduces support for a `tcp_syn_count` parameter in
> libpq, allowing control over the number of SYN retransmissions when
> initiating a connection.
>
> The primary goal is to prevent the walreceiver from getting stuck
> resending SYNs for an extended period, up to
> `net.ipv4.tcp_syn_retries` (127 seconds by default), in the event of
> network disruptions.
>

Thanks for bringing this up and providing this straightforward patch.
Configuring this TCP setting on the WAL receiver side will give us more
precise control over connections, specifically over replication behaviour.
This is especially important in Kubernetes environments with operators like
CloudNativePG, where modifying this setting at a lower level may not be
feasible due to separation of duties and permission constraints.

Ciao,
Gabriele
--
Gabriele Bartolini
VP, Chief Architect, Kubernetes
enterprisedb.com