Comments on: Potential problems with preforking Ruby on Rails

By: James Pharaoh

James Pharaoh — Tue, 12 Jul 2011 07:16:57 +0000

Leaking IO handles is a problem I’ve had, and generally it’s only a problem when the child process is a daemon. For example, I start a background process from a web server, then the web server ends. The child process inherited the open server socket from the web server and still has it open. The web server can now not start again because the socket can’t be reopened on the same port. There are many simiilar situation which can arise from the same.

This isn’t really a ruby thing but a general unix processes thing. Basically you need to close any open IO handles after forking before executing a new process.

By: Hongli

Hongli — Thu, 06 Dec 2007 20:57:50 +0000

Jenn, what “potential risks” are you talking about? Forking is a well-known and well-understood concept. Whatever problems that may arise are simply implementation issues that can be fixed. It’s not black magic.

By: Ruby Developer

Ruby Developer — Thu, 06 Dec 2007 19:16:24 +0000

I don’t think there are potential risks are worth it. Let’s stay away from Forking people, unless you want to spend endless nights of Christmas fixing stuff.

Jenn

By: Ruby Garbage Collection Links « Open Source Teddy Bears

Ruby Garbage Collection Links « Open Source Teddy Bears — Mon, 25 Jun 2007 07:44:48 +0000

[...] * Hongli Lai [...]

By: Hongli

Hongli — Tue, 29 May 2007 23:02:22 +0000

What I do is forking before any requests (but after Rails has been loaded). Wouldn’t that solve all problems?

By: Marcin Raczkowski

Marcin Raczkowski — Tue, 29 May 2007 20:41:59 +0000

problem with database connections is that when you try to do 2 gueries CONCURENTLY two processes use same descriptor which can cause unexpected behavior – i’m currently working on fixing that isue with my mongrel modiication – it should allow mongrel to fork on request, i’m using your script for preloading – and i’m going to release my modifications on compatibile OS license

greets
Marcin Raczkowski

By: HelloWorld

HelloWorld — Sat, 28 Apr 2007 10:07:49 +0000

Peace people

We love you

By: Hongli

Hongli — Thu, 05 Apr 2007 23:40:57 +0000

Oops, you’re right, I forgot to disable reloading of classes. I’ve fixed my blog post now, thank you for pointing this out. The memory savings turned out to be far better than expected: from 55% to 75%!

By: Ezra

Ezra — Thu, 05 Apr 2007 22:01:52 +0000

With the rails config settings you showed in your last post:

config.cache_classes = false
config.whiny_nils = true
config.breakpoint_server = false
config.action_controller.consider_all_requests_local = true
config.action_controller.perform_caching = false
config.action_view.cache_template_extensions = false
config.action_view.debug_rjs = false

You are basically running in development mode which means rails does a lot of reloading of classes and db handles on each request. In production mode this does not happen. Please use a standard rails production mode config with caching turned on and try your experiments again. I’m interested to see what you find out.