Comments on: Apache Update

By: Rodrigo Rosenfeld Rosas

Rodrigo Rosenfeld Rosas — Fri, 30 Oct 2009 00:01:58 +0000

You could also try JRuby or Ruby 1.9 in the hope that they would reduce rails memory usage by using Java threads or native threads, respectively. JRuby uses a higher footprint but it will probably not increase very much the memory usage with more http requests… I’ve not tested both of them, but I really don’t have any problems with memory at my work…Give it a try.

By: Ken Bloom

Ken Bloom — Thu, 29 Oct 2009 15:43:49 +0000

If Redmine (i.e. Rails) forks a couple of processes to get its work done, then theoretically most of the rails code that the two processes share in common should be on copy-on-write pages. In practice, what happens is that the mark-and-sweep garbage collector marks all of the shared pages causing them to be different and unshared. Ruby enterprise edition refactors the garbage collector so that the marking done by the garbage collector is done on a few pages separate from the rest of the heap. That way all of the shared Rails code, which isn’t going to change and isn’t going to get garbage collected stays shared between the two processes.

(If you launch the two Redmine processes separately, then you’re SOL, but I doubt that’s why you have two Redmine processes running.)

By: Ken Bloom

Ken Bloom — Thu, 29 Oct 2009 15:39:17 +0000

pss (proportional set size, where each page’s size is divided by the number of processes that share that page) from /proc/$PID/smaps is probably a better metric
summing up the others, such as Shared_Clean, Shared_Dirty, Private_Clean, and Private_Dirty can also give you a good idea of the process’s memory usage.

By: John Goerzen

John Goerzen — Thu, 29 Oct 2009 13:31:27 +0000

I was referring to varnish, which is a caching reverse proxy.

By: gregf

gregf — Thu, 29 Oct 2009 12:40:13 +0000

Would suggestion looking into running your rails apps with ruby enterprise edition, as well as mod_rack aka mod_rails. Have done the same thing on my slice, switching to the event mpm. Would also consider running apache on another port with nginx in front or even lighttpd to cache/load static files. Less apache has to spin up processes the more your going to save in the long run.

By: John Goerzen

John Goerzen — Thu, 29 Oct 2009 12:39:03 +0000

There was very little shared between the processes — only a few MB. What metric would you suggest though?

By: Adam Skutt

Adam Skutt — Thu, 29 Oct 2009 10:51:13 +0000

You do know that using RSS as a measure of memory efficiency is rather useless, right? That the Apache processes may be sharing 20-30M of resident pages, all of which will still appear in RSS?

As such, if it was a lack of memory that was tipping you before, it will still probably tip you now.

By: Rodrigo Rosenfeld Rosas

Rodrigo Rosenfeld Rosas — Thu, 29 Oct 2009 10:18:00 +0000

Before blaming Rails, I would suggest you to read a bit about deployment with Ruby on Rails.

I’m currently using Redmine with apache + passenger, in a virtual machine with 256MB and we’re good. I just set Apache and Passenger to use only 2 instances, which works perfectly for us.

If you would like to reduce your memory footprint perRedmine instance, you could use ruby-enterprise that would save you about 33% of memory per instance…

We are currently using MPM-worker, but I didn’t try the MPM-event.

You could possible get a smaller footprint than 50MB (or even 33% less) with other languages (Perl, PHP, Python) but there would be trade-offs.

Rails allows the developer to focus on system logic, instead of boiler plate code. This helps to get a cleaner and tested code and that is one reason why Redmine is awsome.

But RAM is really cheap nowadays and I wouldn’t care about 10 instances of Redmine in a cluster using less than 500MB, if you are expecting that much traffic…

By: Ramūnas

Ramūnas — Thu, 29 Oct 2009 09:37:38 +0000

And there is also mod_cache.

By: Harmen

Harmen — Thu, 29 Oct 2009 08:49:28 +0000

The reverse proxy (like pound or nginx) is not a caching proxy! The name can be a little deceiving, but the only thing they do is managing requests and making sure the right httpd handles a request. They are not supposed to cache anything (well, they usually _can_, but it’s not their reason of existence).

By: Paul Tötterman

Paul Tötterman — Thu, 29 Oct 2009 06:50:05 +0000

mod_rails works with apache too. It doesn’t run rails processes when it doesn’t have to.

By: Steve

Steve — Thu, 29 Oct 2009 03:18:20 +0000

Considered Varnish?

By: someone

someone — Thu, 29 Oct 2009 03:15:09 +0000

Please file a bug on egroupware about that. Maybe someone will fix it if they adopt it. You might want to be that person, or make a QA upload.