Rails and J2EE middleware (threading/servers)


#1

A lot of applications have a middleware layer. In some ways,
ActiveRecord or Mailer is thought of as a middleware.

But, for example with J2EE, you can run background servers and threads.
Can this be done with Ruby and how?


#2

Berlin B. wrote:

A lot of applications have a middleware layer. In some ways,
ActiveRecord or Mailer is thought of as a middleware.

But, for example with J2EE, you can run background servers and threads.
Can this be done with Ruby and how?

I take the code I need to run separate from rails and set it up as a
system daemon. I put all of these in my lib/standalone/
directory. Example:

/var/www/myapp/lib/standalone/report_generator

/etc/init.d/report_generator start|stop|restart

My rails app communications via Unix sockets to my report_generator.

Zach


#3

That is interesting. I like that approach. How does the ruby client
code work. Basically, does it timeout or cause a lot of issues.


#4

Berlin B. wrote:

That is interesting. I like that approach. How does the ruby client
code work.

The client just opens a Socket connection to the server, and sends it
instructions. The server takes the instructions, and the
server process creates a new thread and does whatever it needs to do
based on instructions. We make the following assumption:

  • the server knows how to parse basic instructions so it can load the
    correct library/worker and pass on worker-specific
    instructions to it
  • the client understands the format of instructions

Basically, does it timeout or cause a lot of issues.

A handful of times it was reported that it didn’t correctly generate the
report for the end user, however, it was hit half a
million times in about 2 weeks and it’s hard to prove a handful of times
something not working. Although I am investigating. =)

The biggest issue we’ve seen is memory consumption. We use this tactic
for generating CSV reports from a database. Some CSV
reports which include 45,000 or greater (upward of 275,000) records can
really suck up the memory. We have avoided this as being a
huge problem by doing two things:

  1. beefing up server memory
  2. restarting our worker processes (and daemon processes) periodically
    if memory consumption gets way to high.

There are some changes I am making to my system to fix these initial
issues, if interested contact me off list…

Zach