One of our developers had enough luck to see new Google design which is pretty simple and clean.
Sure he made few screen-shots and we glad to share it now with All World.
And surely we hope Google will approve it for mass use and tomorrow we will see it on almost any browser in the World.
Comments are welcome!
I assume that you already made your best with help of your favorite programming language
and recommended postgresql performance tips: http://www.postgresql.org/docs/8.4/static/performance-tips.html
No doubt that standard postgresql configuration is far from modern production environments.
Therefore you need to spend enough time with following sources.
1. resource consumption documentation:
http://www.postgresql.org/docs/8.4/static/runtime-config-resource.html
The most important parameters are:
work_mem (integer)
shared_buffers (integer)
2. Query Planning documentation:
http://www.postgresql.org/docs/current/static/runtime-config-query.html
The most important parameters are:
effective_cache_size (integer)
random_page_cost (floating point)
The default sizes in the GENERIC kernel are insignificant also and waiting for your tuning as well.
Posgtresql doesn’t start without enough memory size so always know when you need to increase kern.shminfo.shmmax.
Setting that we can change in /etc/sysctl.conf
the maximum number of System V IPC system-wide semaphore sets (and identifiers) which can exist at any given time:
kern.seminfo.semmni
the maximum total individual System V IPC semaphores which can be assigned by applications:
kern.seminfo.semmns
the amount of shared memory available in the system (bytes):
kern.shminfo.shmmax
the maximum number of shared memory segments:
sysctl kern.shminfo.shmseg
Full list of setting you can see with:
# man sysctl
OpenBSD kernel parameters
So, there are set of parameters that can be tuned only with kernel rebuild.
You should tune them only if system works unstable with default values and you have:
kernel warnings: “uvm_mapent_alloc: out of static map entries”
or panics like: “panic: malloc: out of space in kmem_map”
NKMEMPAGES
This option defines number of pages in kernel kmem_map structure.
MAX_KMAPENT
It defines number of static entries in kernel kmem_map (kernel virtual memory).
They can be changed in:
/usr/src/sys/arch/conf/GENERIC
As start you need to recheck ‘Building the System from Source’ part of OpenBSD documentation:
http://openbsd.org/faq/faq5.htm
Usually administrators select these parameters using set of tests on dedicated testing box where
they emulate load of production servers.
our test server: 1x Intel Quad core CPU, 2GB RAM
software: Ruby on Rails application, postgresql DB, memcached.
load: about 15.000 users/day, peak load: 10 users/sec.
postgresql_dir/data/postgresql.conf
1 2 3 4 5 6 7 8 9 | # RESOURCE USAGE shared_buffers = 738MB max_prepared_transactions = 30 work_mem = 16MB max_fsm_pages = 2000000 # QUERY TUNING effective_cache_size = 512MB random_page_cost = 1.7 |
/etc/sysctl.conf
1 2 3 | kern.seminfo.semmni = 256 kern.seminfo.semmns = 2048 kern.shminfo.shmmax = 805306368 # Shared memory segment size is 768M |
/usr/src/sys/arch/conf/GENERIC
1 2 3 | ## custom settings option MAX_KMAPENT = 3072 option NKMEMPAGES = 32768 |
Even on mid-size applications logs grow enormously fast, it’s a pity Rails doesn’t provide built-in functionality for that like Apache web-server does. Fortunately there is an easy and fast solution for that issue.
“cronolog [http://cronolog.org/] is a simple filter program that reads log file entries from standard input and writes each entry to the output file specified by a filename template and the current date and time.”
For details, and list of parameters see: [http://cronolog.org/usage.html]
On GNU/Linux Debian:
# apt-get install cronolog
Edit necessary environment file: like ‘config/environments/production.rb’ file
1 2 3 4 5 | # system logger configuration # config.logger = SyslogLogger.new config.logger = Logger.new(IO.popen("FULL_PATH_TO_CRONOLOG log/production.log.%Y%m%d", "w")) config.logger.level = Logger::INFO |
That’s all, fast and easy .. Enjoy!
We have common task: image scaling [http://en.wikipedia.org/wiki/Image_scaling], and correct understanding that: we can’t ask users to provide image of appropriate sizes, just use width and height CSS parameters for images, and thumbnail is always required feature.
Luckily we have ImageMagic library [http://www.imagemagick.org] and program interfaces for popular languages.
install RMagic gem
# gem install rmagick
add small code:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | require 'rubygems' require 'RMagick' class ImageController < ApplicationController def index # determine basic params w = params[:w] h = params[:h] path = params[:path] if !w.to_s.empty? && !h.to_s.empty? && File.exists?(path) begin image = Magick::Image.read(path).first transformed_image = image.resize_to_fill(w.to_i, h.to_i) # send image send_data(transformed_image.to_blob, :disposition => 'inline', :type => "image/#{image.format.downcase}") rescue Exception => e Rails.logger.error e.message Rails.logger.error e.backtrace.join("\n") render :text => "Error processing image #{type}/#{aliaz}", :code => 404, :layout => false end end end |
Here to re-size images we use ‘resize_to_fill’ ImageMagic method:
re-size the image to fit within the specified dimensions while retaining the aspect ratio of the original image, and if necessary, crop the image in the larger dimension.
Sure you understand that resizing takes time and so you should cache re-sized images.
For additional info look thru:
[http://studio.imagemagick.org/RMagick/doc/]
Ruby on Rails is a great framework that still luck some common features, among them: multi-domain support.
Here I will describe fast solution that doesn’t work for every browser and another one that do the work.
Ok, you did your homework and google something like ‘ruby on rails multi-domain’.
Very often provided solution:
edit environment.rb
1 | config.action_controller.session = {:domain => '.mydomain.com'} |
With that parameter Rails always read cookies from same domain. In real some browsers forbid for applications to read cookies from other domain due to insecurity of that operation. And as Mozilla Firefox in set of browsers that forbid that we just need another solution.
Now it’s clear that we should implement necessary functionality other way.
environment.rb:
1 | config.action_controller.session_store = :active_record_store |
and then execute rake task that create necessary DB migration:
1 | rake db:sessions:create |
Apply it with: rake db:migrate.
environment.rb:
1 2 3 4 5 6 7 8 9 | require "rubygems" require "active_support" config.action_controller.session = { :session_key => '_myapp_session_id', # session identification key :secret => '89sHslddfsd98klasdKd', # hash code of session generator(make it random and longer) :cookie_only => false, :expire_after => 1.week, # TTL (time to live) } |
application_controller.rb:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | before_filter { |controller| opts = controller.request.session_options key = opts[:key] # use session ID if it's passed if controller.params[key] # session initialization with old ID controller.session[:nothing] opts[:id] = controller.params[key] controller.request.session_options = opts # session initialization with new ID controller.session[:nothing] end } |
We need to pass session ID as parameter when user change domain name, and within domain we still use cookie.
1 | “#{request.session_options[:key]}” => request.session_options[:id] |
It’s wise to use session initialization before request.session_options[:id] invocation due to Rails use lazy loading, and session can be uninitialized.
Use something like: session[:nothing].
Pay attention that information that Rails get from cookie has bigger priority, and so if you have some parameter in cookie Rails will use it firstly.
Note:
An attacker can still steal you session ID by sniffing the network, or exploiting javascript, he/she gets the value from the cookie itself. If you care about security so much just use HTTPS.
