Sqlite + uwsgi + cosockets.. ?

lehibou015 · 2014-04-13T23:07:19+00:00

Hello! On Sat, Apr 12, 2014 at 4:50 PM, marco wrote: > I'm trying to read the response headers in the log_by_lua filter. I've been > unsuccessfully t...

Sqlite + uwsgi + cosockets.. ?

lehibou015

Hello,

I would like to know if the following configuration would be blocking or not :

1) get a request from the client to openresty (ok, nothing special there) which will query a sqlite database.
2) ask uwsgi on port, say, 9000 to make the query
3) retrieve the result in cosocket/nginx and continue the treatment by setting a cookie value and other stuffs in nginx.

This last part cannot be done in uwsgi because of some internal security implications (not related to uwsgi).

I would like to avoid writing a tcp wrapper for sqlite3.

any hopes for me ?

Thanks

lehibou015

Or maybe proxy_pass to another nginx server , on port 11000, which will only do the database stuffs and answer directly from there to the client.
The other treatments will be done by lua directly in nginx.

Like that, the initial frontend is released, but still, the proxied server will block.. Not good..

agentzh

Hello!

On Sun, Apr 13, 2014 at 8:07 AM, Larry C wrote:
> I would like to know if the following configuration would be blocking or not
> :
>
> 1) get a request from the client to openresty (ok, nothing special there)
> which will query a sqlite database.
> 2) ask uwsgi on port, say, 9000 to make the query
> 3) retrieve the result in cosocket/nginx and continue the treatment by
> setting a cookie value and other stuffs in nginx.
>

The ngx_lua module's cosocket will not block on I/O, just as nginx
upstream modules like ngx_proxy.

Regards,
-agentzh

lehibou015

Thanks!

So the only thing to avoid is to load the sqlite binding directly in nginx/openresty with a require on top and do the query directly in the location rewritten by lua, right ?

That would be blocking, I get this correctly ?

agentzh

Hello!

On Sun, Apr 13, 2014 at 12:50 PM, Larry C wrote:
> So the only thing to avoid is to load the sqlite binding directly in
> nginx/openresty with a require on top and do the query directly in the
> location rewritten by lua, right ?
>

If you call into SQLite's C API directly in nginx/openresty, then it
will surely block on disk I/O if your database is backed by disk. The
blocking effect might not be a problem if your database is in-memory,
depending on your usage. Better measure it if it is the case.

> That would be blocking, I get this correctly ?
>

Correct. Either blocking on disk I/O or blocking on memory-accesses and CPU.

Regards,
-agentzh