Rails 3.2 + RESTful API速度慢

Question

I'm working on a collection of RoR applications and I implemented an API system to let them exchange data.

Implementation details

Libraries

• rails 3.2.8
• ruby 1.9.2 p320
• jbuilder 0.8.2 (API srv)
• httparty 0.9.0 (API cli)

Authorization

An access token is required in order to get access to the API

Security

Self-signed SSL certicates in development environment. Use of SSL for API calls in order to prevent the access token to be stolen (httparty automatically ignore SSL warnings).

Scenario

APP1 exposes data providing an API

APP2 exposes data providing an API

APP3 exposes data providing an API

APP4 needs APP1, APP2, APP3 data and use the APIs in order to get it.

Issue

The first call to the API is slow (2 - 3 seconds of delay for each APP, subsequent calls are fast ~50 ms). I think that is delay manifests, because APP4 needs to connect to APP*, then the connection is mantained, is this right?

Any suggestion to debug/solve the problem?

Many thanks, Mauro

UPDATE (2012-10-25)

Added output (ruby-prof) on API SRV APP: https://gist.github.com/3950920

Answer 1

I found the problem and I want to share the solution with you.

By default Passenger brings up application when needed (in order to save memory, cpu, ...). For this reason the first call to API of each application (APP1, APP2 & APP3) took up to 2 - 3 seconds.

To solve the issue I preload applications using the correct Passenger directive found at http://www.modrails.com/documentation/Users%20guide%20Apache.html#PassengerPreStart

Follows my rails configuration:

# Load passenger module and set paths
# The following three lines MUST be updated whenever the 'passenger-install-apache2-module' is executed
LoadModule passenger_module /usr/local/rvm/gems/ruby-1.9.3-p286/gems/passenger-3.0.17/ext/apache2/mod_passenger.so
PassengerRoot /usr/local/rvm/gems/ruby-1.9.3-p286/gems/passenger-3.0.17
PassengerRuby /usr/local/rvm/wrappers/ruby-1.9.3-p286/ruby

# Speeds up spawn time tremendously -- if your app is compatible. 
# RMagick seems to be incompatible with smart spawning
# Older versions of Passenger called this RailsSpawnMethod
PassengerSpawnMethod smart

# Keep the application instances alive longer. Default is 300 (seconds)
PassengerPoolIdleTime 1000

# Keep the spawners alive, which speeds up spawning a new Application
# listener after a period of inactivity at the expense of memory.
RailsAppSpawnerIdleTime 0

# Just in case you're leaking memory, restart a listener 
# after processing 5000 requests
PassengerMaxRequests 5000

# Automatically hit your site when apache starts, so that you don't have to wait
# for the first request for passenger to "spin up" your application. This even
# helps when you have smart spawning enabled. 
PassengerPreStart http://app1.mydomain.com/
PassengerPreStart http://app2.mydomain.com/
PassengerPreStart http://app3.mydomain.com/
PassengerPreStart http://app4.mydomain.com/