ActiveRecord, blocking or async, logging, syslog/udp

[marcbey]

Here’s a gedanken experiment for those w/ far more knowledge than I
about
ActiveRecord, etc.:

Let’s say my database is very remote and on a very slow machine. Let’s
further say that my app has an action that leads to a very simple insert
into the “impressions” table of the db, a la “INSERT INTO
impressions(docid)
VALUES($docid);” - and let’s say the db automatically adds created_at as
now() and autoincrements primary key.

Will RoR/AR block on this insert? If so is there a way to make it
non-blocking (asynchronous)?

Alternatively, let’s say I wanted to log such impressions on a remote
log
server using UDP and syslog - any guidance on doing that? (Not all
logging
mind you, but just this specific case).

Thanks,

Marc

[marcbey]

In general ActiveRecord will block on this kind of request.

There’s a product called BackgroundDB that was built for offloading slow
pages.
I’m not sure what the status is on that product, or if there’s anything
newer.

This tends to be problematic but you can also do this.

If you want to return the page quickly without waiting for the outcome,
you can fork a thread to handle the mysql insert, and return a page that
doesn’t contain the results of that insert.

From past experience the mysql driver doesn’t deal well with threads.
(One of the reasons why Rails is single threaded), so YMMV.

Marc B. wrote:

Here’s a gedanken experiment for those w/ far more knowledge than I
about
ActiveRecord, etc.:

Let’s say my database is very remote and on a very slow machine. Let’s
further say that my app has an action that leads to a very simple insert
into the “impressions” table of the db, a la “INSERT INTO
impressions(docid)
VALUES($docid);” - and let’s say the db automatically adds created_at as
now() and autoincrements primary key.

Will RoR/AR block on this insert? If so is there a way to make it
non-blocking (asynchronous)?

Alternatively, let’s say I wanted to log such impressions on a remote
log
server using UDP and syslog - any guidance on doing that? (Not all
logging
mind you, but just this specific case).

Thanks,

Marc

[marcbey]

What about mysql’s “INSERT DELAYED” - that would allow the server to
take
over, let the client proceed (non-blocking, asynchronous) - and/or
perhaps
INSERT IGNORE ?

m

[marcbey]

insert delayed only work with myisam talbes, and you are surely using
innodb table.

a cool work around can came form mysql-proxy, wich can hold the loging,
and return imediatly.
http://forge.mysql.com/wiki/MySQL_Proxy

mysql-proxy can be used to scale your database with master slave, using
slave to do the read, and master for the write.
far more better than balance and other tcp load balancer.

Marc B. a écrit :

This tends to be problematic but you can also do this.

> into the "impressions" table of the db, a la "INSERT INTO
> log
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