reusing udp sockets

lists · 2015-02-10T16:20:38+00:00

Hello! On Mon, Feb 9, 2015 at 11:29 AM, Matthieu Labour wrote: > I was hoping that I could add data structure to the nginx lua module > In addition to...

reusing udp sockets

lists

Hi,

I'm trying my first steps with nginx and lua, so maybe I'm just doing
it completely wrong...
I want to use a udp socket in content_by_lua. Just opening one, using
it and closing it afterwards works fine, but to save resources I want
to reuse the socket for multiple requests. So instead of freeing it
after the request, I put it in a pool (local variable in my module).
In the next request, I take the socket from the pool, but get the error
"attempt to send data on a closed socket". So it seems the lua-variable
is still there and has not fallen prey to the GC.
The question is, how can I keep the socket open for the next request?

Thanks, Arne

lordnynex

Hello,

ngx.socket.udp does not appear to have a :setkeepalive() method like ngx.socket.tcp. agentzh, is this correct?

On Tue, Feb 10, 2015 at 12:20 AM, <li...@die-jansens.de> wrote:

Hi,

I'm trying my first steps with nginx and lua, so maybe I'm just doing
it completely wrong...
I want to use a udp socket in content_by_lua. Just opening one, using
it and closing it afterwards works fine, but to save resources I want
to reuse the socket for multiple requests. So instead of freeing it
after the request, I put it in a pool (local variable in my module).
In the next request, I take the socket from the pool, but get the error
"attempt to send data on a closed socket". So it seems the lua-variable
is still there and has not fallen prey to the GC.
The question is, how can I keep the socket open for the next request?

Thanks, Arne
.

agentzh

Hi

On Tue, Feb 10, 2015 at 10:18 AM, Lord Nynex wrote:
> ngx.socket.udp does not appear to have a :setkeepalive() method like
> ngx.socket.tcp. agentzh, is this correct?
>

Yes, correct. Volunteers welcome and patches welcome :)

Regards,
-agentzh

brian

What would be "kept alive" in a UDP socket? Some memory allocations, etc?

agentzh

Hello!

On Wed, Feb 11, 2015 at 4:00 PM, Brian Akins wrote:
> What would be "kept alive" in a UDP socket? Some memory allocations, etc?
>

More importantly, it can save the (expensive) socket(), ioctl(), and
close() syscalls for the UDP/datagram socket upon every request.

Regards,
-agentzh

lists

On 02/12/2015 01:14 AM, Yichun Zhang (agentzh) wrote:
> Hello!
> 
> On Wed, Feb 11, 2015 at 4:00 PM, Brian Akins wrote:
>> What would be "kept alive" in a UDP socket? Some memory allocations, etc?
>>
> 
> More importantly, it can save the (expensive) socket(), ioctl(), and
> close() syscalls for the UDP/datagram socket upon every request.

So I take it that I currently can't do that. What I'm wondering about is
why the socket gets closed in the first place, even though the variable
doesn't go out of scope. What is the reasoning behind this?

Thanks, Arne

> 
> Regards,
> -agentzh
>

agentzh

Hello!

On Wed, Feb 11, 2015 at 11:42 PM,  li...@die-jansens.de wrote:
>
> So I take it that I currently can't do that. What I'm wondering about is
> why the socket gets closed in the first place, even though the variable
> doesn't go out of scope. What is the reasoning behind this?
>

According to the current implementation, cosocket objects' lifetime
and scope cannot go across the creating request handler's boundary.
One has to rely on ngx_lua's builtin connection/socket pools to reuse
the underlying connections/sockets. This design decision eliminates
many (if not all) programming mistakes by incorrectly sharing cosocket
objects across different nginx requests and it also simplifies
resource management.

Regards,
-agentzh