Re: [Openvpn-devel] [PATCH] Increase listen() backlog queue to 32
Hi, On 16/08/2019 13:49, David Sommerseth wrote: > On 15/08/2019 17:53, Gert Doering wrote: >> For reasons historically unknown, OpenVPN sets the listen() backlog >> queue to "1", which signals the kernel "while there is one TCP connect >> waiting for OpenVPN to handle it, refuse all others" - which, on >> restarting a busy TCP server, will create connection issues. >> >> The exact "best" value of the backlog queue is subject of discussion, >> but for a server that is not extremely busy with many connections >> coming in in parallel, there is no real difference between "10" or "500", >> as long as it's "more than 1". >> >> Found and debugged by "mjo" in Trac. >> >> Trac: #1208 >> >> Signed-off-by: Gert Doering > > Acked-By: David Sommerseth > > I agree with Antonio, and we should make it somewhat easier to modify. I disagree with you on this point :D This is not something we expect people to play with. This is only a value that a developer with networking knowledge is expected to find and tweak. Hence my suggestion to make it a define in some header main header file. > I'm > not sure if there's value in having it as a runtime option, like > --socket-backlog (or something like that), or as a value you can pass to > ./configure at compile time. > Like above: yet another config option that the average joe can mess up and come up with unknown problems nobody will understand? nonono ;) Cheers, > > > > ___ > Openvpn-devel mailing list > Openvpn-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/openvpn-devel > -- Antonio Quartulli signature.asc Description: OpenPGP digital signature ___ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
Re: [Openvpn-devel] [PATCH] Increase listen() backlog queue to 32
On 15/08/2019 17:53, Gert Doering wrote: > For reasons historically unknown, OpenVPN sets the listen() backlog > queue to "1", which signals the kernel "while there is one TCP connect > waiting for OpenVPN to handle it, refuse all others" - which, on > restarting a busy TCP server, will create connection issues. > > The exact "best" value of the backlog queue is subject of discussion, > but for a server that is not extremely busy with many connections > coming in in parallel, there is no real difference between "10" or "500", > as long as it's "more than 1". > > Found and debugged by "mjo" in Trac. > > Trac: #1208 > > Signed-off-by: Gert Doering Acked-By: David Sommerseth I agree with Antonio, and we should make it somewhat easier to modify. I'm not sure if there's value in having it as a runtime option, like --socket-backlog (or something like that), or as a value you can pass to ./configure at compile time. -- kind regards, David Sommerseth OpenVPN Inc signature.asc Description: OpenPGP digital signature ___ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel
Re: [Openvpn-devel] [PATCH] Increase listen() backlog queue to 32
Hi,
On 15/08/2019 17:53, Gert Doering wrote:
> For reasons historically unknown, OpenVPN sets the listen() backlog
> queue to "1", which signals the kernel "while there is one TCP connect
> waiting for OpenVPN to handle it, refuse all others" - which, on
> restarting a busy TCP server, will create connection issues.
>
> The exact "best" value of the backlog queue is subject of discussion,
> but for a server that is not extremely busy with many connections
> coming in in parallel, there is no real difference between "10" or "500",
> as long as it's "more than 1".
>
> Found and debugged by "mjo" in Trac.
>
> Trac: #1208
>
> Signed-off-by: Gert Doering
Having 1 is definitely unreasonable, and we need something larger.
On top of that, mjo explained what kind of other side effects we can
have when setting the queue to such a small value.
32 is reasonable and may even be worth a define so that it can be easily
tweaked by whoever wants to. But this is another story..
Acked-by: Antonio Quartulli
> ---
> src/openvpn/socket.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c
> index c472cf1b..983ed38a 100644
> --- a/src/openvpn/socket.c
> +++ b/src/openvpn/socket.c
> @@ -1175,7 +1175,7 @@ socket_do_listen(socket_descriptor_t sd,
> ASSERT(local);
> msg(M_INFO, "Listening for incoming TCP connection on %s",
> print_sockaddr(local->ai_addr, ));
> -if (listen(sd, 1))
> +if (listen(sd, 32))
> {
> msg(M_ERR, "TCP: listen() failed");
> }
>
--
Antonio Quartulli
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[Openvpn-devel] [PATCH] Increase listen() backlog queue to 32
For reasons historically unknown, OpenVPN sets the listen() backlog
queue to "1", which signals the kernel "while there is one TCP connect
waiting for OpenVPN to handle it, refuse all others" - which, on
restarting a busy TCP server, will create connection issues.
The exact "best" value of the backlog queue is subject of discussion,
but for a server that is not extremely busy with many connections
coming in in parallel, there is no real difference between "10" or "500",
as long as it's "more than 1".
Found and debugged by "mjo" in Trac.
Trac: #1208
Signed-off-by: Gert Doering
---
src/openvpn/socket.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c
index c472cf1b..983ed38a 100644
--- a/src/openvpn/socket.c
+++ b/src/openvpn/socket.c
@@ -1175,7 +1175,7 @@ socket_do_listen(socket_descriptor_t sd,
ASSERT(local);
msg(M_INFO, "Listening for incoming TCP connection on %s",
print_sockaddr(local->ai_addr, ));
-if (listen(sd, 1))
+if (listen(sd, 32))
{
msg(M_ERR, "TCP: listen() failed");
}
--
2.21.0
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